Enzyme Glycogen Phosphorylase Research Articles

Multiple pathways for glucose phosphate transport and utilization support growth of Cryptosporidium parvum

Cryptosporidium parvum is an obligate intracellular parasite with a highly reduced mitochondrion that lacks the tricarboxylic acid cycle and the ability to generate ATP, making the parasite reliant on glycolysis. Genetic ablation experiments demonstrated that neither of the two putative glucose transporters CpGT1 and CpGT2 were essential for growth. Surprisingly, hexokinase was also dispensable for parasite growth while the downstream enzyme aldolase was required, suggesting the parasite has an alternative way of obtaining phosphorylated hexose. Complementation studies in E. coli support a role for direct transport of glucose-6-phosphate from the host cell by the parasite transporters CpGT1 and CpGT2, thus bypassing a requirement for hexokinase. Additionally, the parasite obtains phosphorylated glucose from amylopectin stores that are released by the action of the essential enzyme glycogen phosphorylase. Collectively, these findings reveal that C. parvum relies on multiple pathways to obtain phosphorylated glucose both for glycolysis and to restore carbohydrate reserves.

Transient Structural Dynamics of Glycogen Phosphorylase from Nonequilibrium Hydrogen/Deuterium-Exchange Mass Spectrometry.

It remains a major challenge to ascertain the specific structurally dynamic changes that underpin protein functional switching. There is a growing need in molecular biology and drug discovery to complement structural models with the ability to determine the dynamic structural changes that occur as these proteins are regulated and function. The archetypal allosteric enzyme glycogen phosphorylase is a clinical target of great interest to treat type II diabetes and metastatic cancers. Here, we developed a time-resolved nonequilibrium millisecond hydrogen/deuterium-exchange mass spectrometry (HDX-MS) approach capable of precisely locating dynamic structural changes during allosteric activation and inhibition of glycogen phosphorylase. We resolved obligate transient changes in the localized structure that are absent when directly comparing active/inactive states of the enzyme and show that they are common to allosteric activation by AMP and inhibition by caffeine, operating at different sites. This indicates that opposing allosteric regulation by inhibitor and activator ligands is mediated by pathways that intersect with a common structurally dynamic motif. This mass spectrometry approach uniquely stands to discover local transient structural dynamics and could be used broadly to identify features that influence the structural transitions of proteins.

Phytochemicals from Zingiber capitatum rhizome as potential α-glucosidase, α-amylase, and glycogen phosphorylase inhibitors for the management of Type-II diabetes mellitus: Inferences from in vitro, in vivo and in-silico investigations

Diabetes mellitus is known to be one of the most challenging public health issues of the 21st century. The unwanted side effects associated with conventional synthetic antidiabetic medications have compelled the quest for natural antidiabetic drugs. Therefore, in this study, in vitro, in vivo, and in silico antidiabetic effects of Zingiber capitatum methanol extract (ZcME) were evaluated. ZcME exhibited potent inhibitory activity against α-glucosidase as evidenced by an IC50 value of 0.45 mg/ml compared to standard voglibose (IC50 = 0.31 mg/ml). The administration of ZcME at 400 mg/kg significantly (p < 0.05) reduced the fasting blood glucose level compared to the diabetic control group after 20 days of treatment. ZcME decreased blood glucose levels 25.80% on day 1, 45.58% on day 10, and up to 59.17% on day 20 when given at 400 mg/kg BW. Furthermore, GC–MS examination of the plant extracts revealed the presence of sterols, aliphatic acids, aromatics, and esters. In silico study affirm the experimental findings, where the identified compounds showed strong binding affinities against α-glucosidase (7.9 kcal/mol), α-amylase (9.7 kcal/mol), and glycogen phosphorylase enzymes (7.7 kcal/mol), highlighting the antidiabetic potential of ZcME.

The Effect of Inhibition of Perisynaptic Astrocyte Glycogen Utilization on Depression-Like Behavior.

Under physiological conditions, astrocytes produce lactate to meet the increased synaptic energy demand due to neuronal activity. In the light of the findings showing that this process is disrupted in the pathophysiology of major depression, the aim of this study is to investigate the effect of pharmacological inhibition of perisynaptic astrocyte glycogen utilization on anxiety-like behavior and depression-like behavior in female and male mice. In this study, DAB (1,4-dideoxy-1,4-imino-D-arabinitol), which is an inhibitor of glycogen breaking enzyme glycogen phosphorylase, was intrahippocampally administered to 15 female and 14 male Swiss albino mice, while 15 female and 12 male Swiss albino mice received intrahippocampal saline injections. Three and five days after the injections, the anxiety-like and depression-like behaviors of the mice were assessed by locomotor activity, open-field test, light-dark box test, tail suspension test and sucrose preference test. Three days after injection, neither depression-like nor anxietylike significant behavioral changes were detected in the male experimental group mice compared to the control group; but an increase in locomotor activity (p=0.05) and time spent in the open-field (p=0.01) were observed on the fifth day. In evaluations of the female experimental group mice on the third and fifth days, depression-like and anxiety-like behaviors were found similar to the control group, as seen in the male mice. The only significant difference in the experimental group female mice was found in the sucrose preference test, which revealed an increased tendency to prefer sucrose (p=0.003) compared to the control group. The inhibition of glycogen use in the hippocampus by DAB did not affect anxiety-like and depression-like behaviors 3 and 5 days after injection in both female and male mice. The increase in the time spent in the open-field by male experimental group mice was associated not with anxiety, but with increase in the locomotor activity. The fact that no significant difference was observed in the light-dark box test, which is another test used to evaluate anxiety, supported this opinion. The increase seen in the sucrose preference test in female experimental group mice was not interpreted as an increase in hedonic behavior because prevention of glycogen breakdown in the hypothalamus might have homeostatically increased sugar-craving and therefore resulted in an increase in sucrose preference. Different set of tests better targeting the energy and glucose metabolism and applied at farther time points than surgery are recommended for future studies.

Molecular mechanisms of glycogen particle assembly in Escherichia coli

It has been reported that glycogen in Escherichia coli has two structural states, that is, fragility and stability, which alters dynamically. However, molecular mechanisms behind the structural alterations are not fully understood. In this study, we focused on the potential roles of two important glycogen degradation enzymes, glycogen phosphorylase (glgP) and glycogen debranching enzyme (glgX), in glycogen structural alterations. The fine molecular structure of glycogen particles in Escherichia coli and three mutants (ΔglgP, ΔglgX and ΔglgP/ΔglgX) were examined, which showed that glycogen in E. coli ΔglgP and E. coli ΔglgP/ΔglgX were consistently fragile while being consistently stable in E. coli ΔglgX, indicating the dominant role of GP in glycogen structural stability control. In sum, our study concludes that glycogen phosphorylase is essential in glycogen structural stability, leading to molecular insights into structural assembly of glycogen particles in E. coli.

A novel description of the Vastus lateralis morphology of the Temminck's ground pangolin (Manis temminckii).

The pangolin (Manidae family) is the world's most trafficked animal, yet very little is known about its physiology and metabolism primarily due to its inconspicuous and solitary nature. Skeletal muscle samples from the Vastus lateralis were collected postmortem from a single female Temminck's ground pangolin (Manis temminckii). Samples were analyzed for fiber type composition, fiber size and myosin heavy chain isoform content. The oxidative and glycolytic metabolic capacity was determined through citrate synthase, 3-hydroxyacetyl co A dehydrogenase, creatine kinase, lactate dehydrogenase, phosphofructokinase and glycogen phosphorylase enzyme activities. Lastly, antioxidant capacity was determined through superoxide dismutase and catalase enzyme activities, and the total antioxidant capacity. The pangolin metabolic profile was then compared to other endurance and nonendurance mammals, in which data were standardized relative to human endurance athletes in order to provide context. Slow twitch type I fibers, rich in mitochondria were the predominant fiber type within the pangolin indicating a reliance on oxidative derived energy from fats and carbohydrates. This suggests that the pangolin has a high endurance capability when compared to other wild animals and human endurance athletes. This is the first study to investigate the skeletal muscle physiology and metabolism of any pangolin species, in an attempt to further understand this endangered animal and aid with conservation efforts.

Physicochemical characterization of C-phycocyanin from Plectonema sp. and elucidation of its bioactive potential through in silico approach.

C-phycocyanin (C-PC), the integral blue-green algae (BGA) constituent has been substantially delineated for its biological attributes. Numerous reports have illustrated differential extraction and purification techniques for C-PC, however, there exists paucity in a broadly accepted process of its isolation. In the present study, we reported a highly selective C-PC purification and characterization method from nontoxic, filamentous and non-heterocystous cyanobacterium Plectonema sp. C-PC was extracted by freeze-thawing, desalted and purified using ion-exchange chromatography. The purity of C-PC along with its concentration was found to be 4.12 and 245 µg/ml respectively. Comparative characterization of standard and purified C-PC was performed using diverse spectroscopic techniques namely Ultra Violet-visible, fluorescence spectroscopy and Fourier transform infrared (FT-IR). Sharp peaks at 620 nm and 350 nm with UV-visible and FT-IR spectroscopy respectively, confirmed amide I bands at around 1638 cm-1 (C=O stretching) whereas circular dichroism (CD) spectra exhibited α-helix content of secondary structure of standard 80.59% and 84.59% of column purified C-PC. SDS-PAGE exhibited two bands of α and β subunits 17 and 19 kDa respectively. HPLC evaluation of purified C-PC also indicated a close resemblance of retention peak time (1.465 min, 1.234 min, 1.097 min and 0.905 min) with standard C-PC having retention peak timing of 1.448 min, 1.233 min and 0.925 min. As a cautious approach, the purified C-PC was further lyophilized to extend its shelf life as compared to its liquid isoform. To evaluate the bioactive potential of the purified C-PC in silico approach was attempted. The molecular docking technique was carried out of C-PC as a ligand-protein with free radicals and α-amylase, α-glucosidase, glycogen synthase kinase-3 and glycogen phosphorylase enzymes as receptors to predict the free radical scavenging (antioxidant) and to target antidiabetic property of C-PC. In both receptors free radicals and enzymes, ligand C-PC plays an important role in establishing interactions within the cavity of active sites. These results established the antioxidant potential of C-PC and also give a clue towards its antidiabetic potential warranting further research.

Molecular docking analysis of glycogen phosphorylase with inhibitors from Cissampelos pareira Linn.

Cissampelos pareira Linn. is a climbing herb known in Indian traditional medicine as laghupatha. It belongs to the Menispermaceae family. The enzyme glycogen phosphorylase (GP) is a promising target for the treatment of type-2 diabetes (T2DM). A variety of natural product inhibitors with both pharmaceutical and nutraceutical potential have been reported in the search for powerful, selective and drug-like GP inhibitors that could lead to hypoglycemic medicines. Therefore, it is of interest to document the molecular docking analysis data of glycogen phosphorylase with compounds from Cissampelos pareira Linn. We report the optimal binding features of 4 compounds namely Trans-N-feruloyltyramine, Coclaurine, Magnoflorine, and Curine with the target protein for further consideration in the context of T2DM.

The feeding status regulates the action of insulin and 20-hydroxyecdysone on haemolymph trehalose level in Bombyx larvae.

Insulin in mammals is known for its effect on carbohydrate metabolism and maintenance of blood sugar levels. In the present study, we explored the effect of exogenous insulin and 20-hydroxyecdysone (20E) on carbohydrate metabolism in Bombyx mori under the fed and food-deprived conditions. The study showed that insulin and 20E regulate the trehalose (major circulating sugar) level in B. mori, and larval feeding status plays a decisive role in influencing the action of these two hormones. At feeding, both insulin and 20E showed its hypertrehalosemic action but at food deprivation, these hormones acted as hypotrehalosemic factors. Although both insulin and 20E showed the same effect on the haemolymph trehalose level either at feeding or food deprivation, the metabolic regulation was different for these two hormones. Insulin treatment to fed larvae increased the haemolymph trehalose level without altering the effectiveness of trehalose utilization but possibly by inducing the activity of glycogen phosphorylase enzyme and releasing glucose-1-P for the increased synthesis of trehalose. The treatment of 20E to fed larvae also increased the trehalose level, but concurrently it also increased both the enzyme activity of trehalase and glycogen phosphorylase. Insulin treatment to food-deprived larvae decreased the circulating trehalose level by increasing the trehalose breakdown as the mRNA expression level of trehalase-2 and enzyme activity of trehalase increased in these larvae. The treatment of 20E to food-deprived larvae decreased the haemolymph trehalose possibly by decreasing its synthesis, as glycogen phosphorylase enzyme activity decreased in these larvae, thus restricting the availability of glucose-1-P for trehalose synthesis. The study, thus suggests that both insulin and 20E regulate carbohydrate metabolism in B. mori.

Evaluation of Antidiabetic and Antihyperlipidemic Effect of Ethanolic Leaves Extract of Centratherum anthelminticum (L) Kuntze against STZ Induced Diabetic Rats

Objective: To evaluate the Antidiabetic &amp; Antihyperlipidemic effect of Centratherum Anthelminticum (L) Kuntze extract against STZ induced diabetic rats.&#x0D; Methods: The present study examined the influence of Centratherum Anthelminticum extract (CASE), on blood glucose level and antioxidant enzymes level in STZ induced diabetic rats. The possible effects of chronic administration of the extract on the fasting serum glucose, insulin, and total cholesterol and triglycerides levels in STZ-induced diabetic rats were also evaluated.&#x0D; Results: The extracts showed a marked Antidiabetic &amp; Antihyperlipidemic effect. Centratherum anthelminticum ethanolic seeds extract is capable of exhibiting glycemic control through its inhibitory effect on glycogenolytic enzyme glycogen phosphorylase, gluconeogenic enzymes such as glucose-6-phosphatase and fructose-1, 6-bis phosphatase and stimulatory effect on hexokinase, which is the key enzyme in the glycolytic pathway.&#x0D; Antihyperlipidemic activity of Centratherum anthelminticum ethanolic seeds extract proved by restoration of altered lipid profile&#x0D; Conclusions: The results of the study indicate that the extract of Centratherum anthelminticum possesses strong antidiabetic &amp; antihyperlipidemic activity. This study also describes therapeutic effect of Centratherum anthelminticum in diabetes which will give a new direction for the future scientific research.&#x0D; Keywords: Diabetes, Centratherum anthelminticum, Pharmacological, Antidiabetic, Antihyperlipidemic

Metabolic Enzyme Acetylation is Elicited in Response to Stress Induced by Cardiac Specific Overexpression of Human ADCY8

INTRODUCTIONCardiac‐specific overexpression of human ADCY8 in mice (TGAC8), induces constant stimulation of the cAMP/PKA pathway in TGAC8 mice that results in a sustained, robust elevation of heart rate and cardiac contraction 24 hours a day, 7 days a week. Although progress has been made in understanding adaptive cardiac remodeling that occurs as a result of acute bouts of exercise, little is known about the effects of chronic, cardiac specific stress. Our initial transcriptomic, proteomic and metabolomic profile of the TGAC8 left ventricle (LV) has afforded some insight into how the heart adapts to this chronic stress: changes in key metabolic enzymes suggest an increase in glycolytic activity and reduction in fatty‐acid substrate support of metabolism. This prompted us to further investigate how this chronic cAMP‐PKA stress alters the bioenergetics of the heart. Due to its role in metabolic regulation, we were particularly interested in the acetylation status of metabolic enzymes in the TGAC8 model.METHODSAcetylation was quantified in the left ventricles of three 90‐day old wild type (WT) and TGAC8 mice. Acetylated peptides were isolated and enriched for label free quantification, using LC‐MS/MS analysis, and subsequent bioinformatic analysis was completed using STRING, Gene Ontology (GO) term enrichment, and Ingenuity Pathway Analysis. Acetylation sites were considered to be significantly different between TGAC8 and WT if the fold change was &gt; 1.5 in either direction and significantly differed at the p &lt; 0.05 level.RESULTSWe identified 6212 acetylated sites across 2206 proteins. Of these, 450 acetylation sites across 225 proteins were significantly different in the TGAC8 compared to WT, with 329 sites across 180 proteins being more acetylated in the TGAC8. STRING analysis revealed that 110 of these 225 proteins localize to the mitochondria: 81 of these being involved in the oxidation‐reduction process; and 58 being involved in oxidoreductase activity. The most significantly enriched GO terms shared common themes of cellular metabolism, fatty acid utilization and aerobic respiration (Fig. ). Proteins with the highest number of sites with significantly more acetylation in the TGAC8 had known roles in fat and glucose metabolism, such as ATP synthase, glycogen phosphorylase, isocitrate dehydrogenase, and various enzymes involved in the terminal steps of beta oxidation (Table ).CONCLUSIONAcetylation changes to key metabolic enzymes suggests a mechanism for alteration in TGAC8 fuel preferences deduced from the initial transcriptomic, proteomic, and metabolomic analysis. Specifically, increased acetylation of enzymes involved in beta oxidation, oxidative phosphorylation, and glucose metabolism, in combination with our previous omics data, suggests that the TGAC8 mouse heart may exhibit a preference for glucose utilization and exhibit impaired fatty acid metabolism.Support or Funding InformationThis research was funded by the Intramural Research Program of the National Institutes of Health, National Institute on Aging.Most significantly enriched GO terms from each subontology.Figure 1 Proteins with the greatest quantity of acetylation sites significantly higher in TGAC8 heart identified by LC‐MS/MS. Gene Name Description # of sites w/higher TGAC8 acetylation Atp5a1 ATP synthase subunit alpha, mitochondrial 10 Pygm Glycogen phosphorylase 10 Alb Serum albumin 7 Acaa2 3‐ketoacyl‐CoA thiolase 6 Eno3 Beta‐enolase 6 Hba‐a2 Alpha globin 1 6 Idh2 Isocitrate dehydrogenase 6 Aco2 Aconitate hydratase 5 Mb Myoglobin 5 Trf Serotransferrin 5 Acadm Medium‐chain specific acyl‐CoA dehydrogenase 4 Aldoa Fructose‐bisphosphate aldolase 4 Ckm Creatine kinase M‐type 4 Eno1 Alpha‐enolase 4 Fh1 Fumarate hydratase 4 Pgk1 Phosphoglycerate kinase 1 4 Sod2 Superoxide dismutase 4 Uqcrc1 Cytochrome b‐c1 complex subunit 1 4 Agl Amylo‐1,6‐glucosidase, 4‐alpha‐glucanotransferase 3 Atp5o ATP synthase subunit O 3

Effect of gradual temperature increase on the carbohydrate energy metabolism responses of the Antarctic fish Notothenia rossii

The warming of the Southern Ocean waters may affect the biological processes and the performance of the fish inhabiting it. The notothenioid group is metabolically specialized to low-temperature environments and may be vulnerable to the climatic changes imposed on the Antarctic continent. However, gradual temperature changes potentially allow an opportunity for plasticity adjustments. The present study evaluated the effect of gradual increase of temperature on the enzymatic and nonenzymatic parameters of energy metabolism in renal, branchial, hepatic, and encephalic tissue of Notothenia rossii subjected to a gradual temperature change of 0.5 °C/day until reaching 2 °C, 4 °C, 6 °C, and 8 °C. Under the effect of an acclimation rate of 0.5 °C/day, the gill tissue showed increased phosphofructokinase (PFK) enzyme activity. In the kidney, there was increased activity of the malate dehydrogenase (MDH), glucose-6-phosphatase (G6PDH), and glycogen phosphorylase (GP) enzymes. There was an increase in lactate concentration in the liver and an increase in GP enzyme activity in the brain. The specific tissue responses indicate the presence of thermal plasticity and an attempt to regulate energy metabolism to mitigate thermal stress in this species under these experimental conditions, possibly through the activation of glycolysis, gluconeogenesis, and glycogenolysis.

Effect of arsenic (As) and lead (Pb) on glycogen content and on the activities of selected enzymes involved in carbohydrate metabolism in freshwater catfish, Heteropneustes fossilis

Heavy metals show a wide range of effect on fishes, out of which arsenic (As) and lead (Pb) are among the leading heavy metal toxicants. These heavy metals are known to alter different biochemical parameters, including glycogen level, in different tissues of fishes. Glycogen level in fish serves as the main source of energy; hence, in this study, the acute toxicity test of As and Pb and their effect on the glycogen content and the enzymes involved therein (glycogen phosphorylase, glycogen synthase, hexokinase, phosphofructokinase and pyruvate kinase) were studied in the liver and muscle tissues of Heteropneustes fossilis. The 96 h LC50 values of As2O3 and PbCl2 on H. fossilis were found to be 35.09 ppm and 66.20 ppm, respectively. On acute exposure to 96 h LC50 values of As2O3 and PbCl2, the glycogen concentration showed a gradual decrease in both liver and muscle tissues of H. fossilis. However, on chronic exposure (LC50/20th ppm), the glycogen content in liver and muscle of H. fossilis was depleted till 20 days; whereas after 30 days, the glycogen level was recovered in both the tissues. The activities of glycogen metabolic enzymes (glycogen phosphorylase and glycogen synthase) and few selected glycolytic enzymes (hexokinase, phosphofructokinase and pyruvate kinase) were also altered in H. fossilis when exposed to acute and chronic concentration of As2O3 and PbCl2. Our present results showed that As and Pb induced toxicity stress on the catfish, H. fossilis, which might have caused to alter the carbohydrate metabolism in the fish.

Synthesis of 3-(7-triphenylphosphonioheptyl)-2,6-dimethyl-1,4-benzoquinone) and The Activity Test Toward Glycogen Phosphorylase Enzyme: In silico Approach

The synthesis of 3-(7-triphenylphosphonioheptyl)-2,6-dimethyl-1,4-benzoquinone) (TFH) is carried out by bromoalkylation and insertion of triphenylphosphonium moiety by refluxed of 2,3-dimethyl-1,4-benzoquinone using bromooctanoic acid triphenylphosphine. The alkylation gave 17.14% yield of 2-(7-bromoheptyl)-3,5-dimethyl-1,4-benzoquinone (C7) and 3-(7-triphenylphosphonioheptyl)-2,6-dimethyl-1,4-benzoquinone) (TFH) is obtained at 40.35% yield. Structure characterization of the synthesized product was performed mainly using UV-Vis, FT-IR, and 1H-NMR. UV-Vis characterization showed maximum wavelength of TFH at 198 nm, 226 nm, and 260 nm. FT-IR characterization showed sp3 character at 2930.43 cm−1 and the disappearance of C-Br peak at 687.37 cm−1, indicates the presence of long chain alkyl group and the replacement of Br with triphenylphosphonium. In silico investigation by using Glycogen Phosphorylase enzyme as molecular target estimated IC50 value of thymoquinone, C7, and TFH, that is, 16.14 ppm, 162.2 ppm, and 1.26 ppm, respectively. Thus, TFH has the smallest IC50 value suggested that most effective drug candidate compared with thymoquinone and C7.

Studies on the reversible enzyme reaction of rabbit muscle glycogen phosphorylase b using isothermal titration calorimetry

Glycogen phosphorylase enzymes (GP) catalyse reversible reactions; the glucose transfer from glycogen to inorganic phosphate (Pi, phosphorolysis) or the reverse glucose transfer from glucose-1-phosphate (G-1-P) to glycogen (synthesis). Rabbit muscle GPb (rmGPb) was used as a model enzyme to study the reversible enzyme reaction. To follow both directions of this reversible reaction, we have developed a novel isothermal titration calorimetry (ITC) method for the determination of the direct reaction rate. The preference of forward or reverse reaction was ensured by the 0.1 or 10 concentration ratios of G-1-P/Pi, respectively. Substrate specificity was studied using different maltooligosaccharides and glycogen. Based on the KM values, glycogen and 2-chloro-4-nitrophenyl maltoheptaoside (CNP-G7) were found to be analogous substrates, which allowed to optimize the method by taking advantage of the CNP chromophore being detectable in HPLC. In case of CNP-G7, substrate inhibition was observed and characterised by Ki of 23 ± 7 mM. Inhibition of human GP is a promising strategy for the treatment of diabetes. Our ITC measurements have confirmed that caffeine and glucopyranosylidene-spiro-thiohydantoin (GTH), as known GPb inhibitors, inhibit the rmGPb-catalysed reversible reaction in both directions. Ki values obtained in the direction of synthesis (1.92 ± 0.14 mM for caffeine and 11.5 ± 2.0 μM for GTH) have been shown to be in good agreement with the Ki values obtained in the direction of phosphorolysis (4.05 ± 0.26 mM for caffeine and 13.8 ± 1.6 μM for GTH). The higher difference between the inhibition constants of caffeine was explained by the non-competitive mechanism.The described ITC method using the developed experimental design and reaction conditions is suitable for activity measurements of different phosphorylase enzymes on various substrates and is applicable for inhibition studies as well.

Defective fasting-induced PKA activation impairs adipose tissue glycogen degradation in obese Zucker rats.

Obesity is associated with development of insulin resistance in adipose tissue (AT). Human obesity has been associated with increased glycogen deposition in adipocytes. Adipocytes synthesise glycogen prior to the formation of lipids. The present study examined adipose glycogen content in obese Zucker rats and the effect of fasting on glycogen-metabolising enzymes. We hypothesised that obesity imposes a blunted response to fasting through impaired activation of glycogen-metabolizing enzymes, which dampens glycogen mobilization in obese Zucker rats. We investigated the effect of 24h fasting on AT glycogen metabolism in12-week old obese Zucker rats. Epididymal fat pads were collected from rats fed ad-libitum and fasted for 24h. Glycogen content, glycogen synthase and phosphorylase enzyme activity, and PKA activity were analysed as well as total and phosphorylated protein content for glycogen-metabolizing enzymes glycogen synthase and phosphorylase, glucose transporter GLUT4, and cAMP-dependent response element binding protein levels. Twelve-week old obese Zucker rats showed increased AT glycogen content (adipose glycogen content [mean ± SD], lean: 3.95 ± 2.78 to 0.75 + 0.69 µg.mg-1; p < 0.005 fed vs fasted, and obese: 5.23 ± 3.38 to 5.019 ± 1.99 µg.mg-1; p = ns fed and fasted and p < 0.005 lean vs obese), and impaired fasting-induced glycogen mobilization following a 24h fast. These defects wereassociated with dysfunctional glycogen-metabolizing enzymes, characterized by: (1) blunted phosphorylation-mediated activation and downregulated protein expression of glycogen phosphorylase, and (2) an impaired phosphorylation-mediated inactivation of glycogen synthase. Furthermore,these defects were related to impaired fasting-induced protein kinase A (PKA) activation. This study provides evidence of a defective glycogen metabolism in the adipose associated with impaired fasting-induced activation of the upstream kinase protein kinase A, which render a converging point to obesity-related primary alterations in carbohydrate and lipid metabolism in the AT.

Can McArdle disease be induced by infection associated with rhabdomyolysis case report?

Introduction: Rhabdomyolysis is the clinicopathologic presentation that is caused by striated muscle damage with leaking of toxic pigments into the blood. Clinical findings of rhabdomyolysis ranges from asymptomatic increase of muscle enzymes to the fatal forms of acute renal failure (ARF) and electrolyte disturbance. The causes of rhabdomyolysis can be classified under several groups: (a) direct injury from trauma, (b) overuse of muscle, (c) congenital muscle enzyme errors, and (d) uncommon pathogens like drugs and toxins, ischemia of muscle, metabolic and endocrine disorders, and finally infections. The diagnosis of rhabdomyolysis is based on myalgia and weakness, tea-colored urine (myoglobinuria), an increase in muscle enzymes that is not caused by myocardial infarction (MI) or polymyositis (PM). The most important goal of treatment is to diagnose and cure complications like electrolyte disturbances and acute tubular necrosis (ATN). Case Report: The case in the present study was a young man who was admitted with fever and chill and generalized myalgia with tea-colored urine. Finally, he died because of acute adult respiratory distress syndrome (RDS), acute renal tubular necrosis, and hyperkalemia. Among congenital muscle enzyme disorders, the most common type is the carnitine-palmitotransferase defect (CPT), and after that, the second most common is myophosphorylase deficiency. Among muscle carbohydrate metabolism defects, McArdle disease (MD), or glycogenosis type V (GSD-V), is the most prevalent, which is caused by a deficiency in glycogen-phosphorylase enzyme. In this disorder, only striated muscles are affected, which leads to rhabdomyolysis in the primary steps, and exercise intolerance, muscle cramps, and myoglobinuria, when reaches more developed levels. This predisposition to rhabdomyolysis in patients with MD prevents us from administrating certain drugs in these cases. Conclusion: Rhabdomyolysis may develop among individuals with abnormal muscles as in congenital diseases of glycogenolysis, glycolysis, purine, and lipid metabolism. Considering the rare causes of rhabdomyolysis like MD permits physicians to diagnose and treat this potentially fatal occult causes.

Exploring the Dual Inhibitory Activity of Novel Anthranilic Acid Derivatives towards α-Glucosidase and Glycogen Phosphorylase Antidiabetic Targets: Design, In Vitro Enzyme Assay, and Docking Studies.

A few new anthranilate diamide derivatives, 3a–e, 5a–c and 7a–d, were designed, synthesized, and evaluated for their inhibitory activity against two interesting antidiabetic targets, α-glucosidase and glycogen phosphorylase enzymes. Different instrumental analytical tools were applied in identification and conformation of their structures like; 13C NMR, 1H NMR and elemental analysis. The screening of the novel compounds showed potent inhibitory activity with nanomolar concentration values. The most active compounds (5c) and (7b) showed the highest inhibitory activity against α-glucosidase and glycogen phosphorylase enzymes IC50 = 0.01247 ± 0.01 µM and IC50 = 0.01372 ± 0.03 µM, respectively. In addition, in vivo testing of the highly potent α-glucosidase inhibitor (7b) on rats with DTZ-induced diabetes was done and showed significant reduction of blood glucose levels compared to the reference drug. Furthermore, a molecular docking study was performed to help understand the binding interactions of the most active analogs with these two enzymes. The data obtained from the molecular modeling were correlated with those obtained from the biological screening. These data showed considerable antidiabetic activity for these newly synthesized compounds.

Correlation of heart-type fatty acid-binding protein and glycogen phosphorylase enzyme BB in brain with septic myocardial injury

The incidence of sepsis is on the rise, and the mortality is also high.Myocardial injury caused by sepsis is one of the important causes of death.However, there is no clear and unified diagnostic criteria to sepsis complicated with myocardial injury.The clinical diagnostic criteria of myocardial injury is mainly based on cardiac ultrasound, myocardial markers and so on.But the measurement of ejection fraction is needed to consider the impact of preload and afterload of left ventricula, also the subjective level of operators.So cardiac markers play an important role in the detection of myocardial injury in sepsis and can reflect the severity of myocardial injury and sepsis, especially in the early diagnosis and prognosis.Heart-type fatty acid binding protein and brain glycogen phosphorylase isoenzyme type exhibit higher sensitivity, specificity and stability compared to other traditional cardiac markers in the clinical diagnosis of myocardial injury, which are worth to be studied and applied in the clinical diagnosis of myocardial injury. Key words: Sepsis; Myocardial injury; Cardiac markers; Heart-type fatty acid binding protein; Brain glycogen phosphorylase isoenzyme type

Self-Assembled Polypeptide Nanogels with Enzymatically Transformable Surface as a Small Interfering RNA Delivery Platform.

Nanometer-size gel particles, or nanogels, have potential for delivering therapeutic macromolecules. A cationic surface promotes cellular internalization of nanogels, but undesired electrostatic interactions, such as with blood components, cause instability and toxicities. Poly(ethylene glycol) coating has been used to shield charges, but this decreases delivery efficiency. Technical difficulties in synthesis and controlling molecular weights make it unfeasible to, instead, coat with biodegradable polymers. Our proposed solution is cationized nanogels enzymatically functionalized with branched polysaccharide chains, forming a shell to shield charges and increase stability. Biodegradation of the polysaccharides by an endogenous enzyme would then expose the cationic charges, allowing cellular internalization and cargo delivery. We tested this concept, preparing maltopentaose functionalized cholesteryl poly(l-lysine) nanogel and using tandem enzymatic polymerization with glycogen phosphorylase and glycogen branching enzyme, to add branched amylose moieties, forming a CbAmyPL nanogel. We characterized CbAmyPL nanogels and investigated their suitability as small interfering RNA (siRNA) carriers in murine renal carcinoma (Renca) cells. The nanogels had neutral ζ potential values that became positive after degradation by α-amylase. Foster resonance energy transfer demonstrated that the nanogels formed stable complexes with siRNA, even in the presence of bovine serum albumin and after α-amylase exposure. The nanogels, with or without α-amylase, were not cytotoxic. Complexes of CbAmyPL with siRNA against vascular endothelial growth factor (VEGF), when incubated alone with Renca cells decreased VEGF mRNA levels by only 20%. With α-amylase added, however, VEGF mRNA knockdown by the siRNA/nanogels complexes was 50%. Our findings strongly supported the hypothesis that enzyme-responsive nanogels are promising as a therapeutic siRNA delivery platform.