Enzymes In Different Tissues Research Articles

Tissue distribution of the enzyme rhodanese in four cyprinid fish species

Rhodanese (thiosulfate: cyanide sulfurtransferase; EC. 2.8.1.1) is a ubiquitous enzyme present in both prokaryotes and eukaryotes. Its physiological function is controversial, but it is believed that the enzyme plays a central role in cyanide detoxification. The purpose of this investigation was to determine and compare the pattern of tissue distribution of rhodanese in different tissues of four cultured cyprinid fish species, including the common carp, grass carp, silver carp, and bighead carp. Rhodanese activity was detected in all tissues studied, albeit in different amounts. Specific activities (enzyme units per milligram protein) of rhodanese in different tissues of the common carp, grass carp, silver carp, and bighead carp range from 0.022 to 0.162, 0.018 to 0.215, 0.038 to 0.180, and 0.034 to 0.221, respectively. The highest activity of rhodanese in all four species was observed in the liver and kidney, followed by the gill and intestine, while the lowest activity was present in the brain. Inter-species differences were not observed in the level of the enzyme in different tissues. The results of this study may indicate the involvement of rhodanese in cyanide detoxification in tissues that have greater potential to be exposed to higher levels of cyanide. However, the widespread tissue distribution of rhodanese suggests additional important biological functions for the enzyme besides cyanide detoxification.

Expression pattern of enzymes related to juvenile hormone metabolism in the silkworm, Bombyx mori L.

The physiological balance of juvenile hormone (JH) in insects depends on its biosynthesis and degradation pathway. Three key enzymes namely, juvenile hormone esterase (JHE), juvenile hormone epoxide hydrolase (JHEH) and juvenile hormone diol kinase (JHDK) are required for degradation in insects. Our present results showed that JHE and JHEH exhibited expression in almost all the tissues. This indicated that JHE and JHEH might degrade JH simultaneously. In addition, the highest levels of JHDK were observed in the midgut, with trace level being found in the malpighian tubule and haemocytes. Since the midgut is a digestive organ and not a JH target, it was hypothesized that both JHE and JHEH hydrolyzed JH to JH diol (JHd) which was then transported to midgut and hydrolyzed further by JHDK, to be finally excretedout of the body. Also the expression studies on JH degradation enzymes in different tissues and stages indicated that the activities of the three enzymes are specific and coincident with the JH functions in silkworm, Bombyx mori L.

A seed coat-specific promoter for canola

The canola industry generates more than $11 billion of yearly income to the Canadian economy. One problem of meal quality is the dark polyphenolic pigments that accumulate in the seed coat. Seed coat-specific promoters are a pre-requisite to regulate the genes involved in seed coat development and metabolism. The beta-glucuronidase (GUS) reporter gene was used to test an Arabidopsis promoter in developing and mature seeds of canola (Brassica napus). The promoter tested is the regulatory region of the laccase gene (AtLAC15) from Arabidopsis thaliana. The AtLAC15 promoter::GUS construct was inserted into canola double haploid line DH12075 using Agrobacterium-mediated transformation. Southern blot analysis using a 536 bp GUS probe showed variation among the transformed plants in the T-DNA copy numbers and the position of the insertion in their genomes. Histochemical assay of the GUS enzyme in different tissues (roots, leaves, stem, pollen grains, flowers, siliques, embryos and seed coats) showed ascending GUS activity only in the seed coat from 10 days after pollination (DAP) to the fully mature stage (35 DAP). GUS stain was observed in the mucilage cell layer, in the outer integument layer of the seed coat but not in the inner integument. The AtLAC15 promoter exhibited a specificity and expression level that is useful as a seed coat-specific promoter for canola.

Distribution of the enzyme rhodanese in tissues of the cat (Felis catus).

The enzyme rhodanese (EC 2.8.1.1) is an ubiquitous enzyme which is present in all living organisms, from bacteria to man. It is speculated that this enzyme plays a central role in cyanide detoxification. However, its wide tissue distribution suggests this enzyme might perform other functions beside cyanide detoxification. Although the distribution of rhodanese in different tissues of human and domestic animals has been studied, little is known about the pattern of distribution and physiological roles of this enzyme in the cat. The purpose of this investigation was to determine the enzyme levels and compare the distribution of this enzyme in different tissues of the cat. A selection of tissue samples was assayed for rhodanese activity. The protein content of tissue extracts and enzymatic activities were calculated as units per gram tissue and units per milligram protein of the tissue. Results showed that in terms of units per milligram protein of the tissue (specific activity of the enzyme), colon and rectum mucosal layers and testis were the richest sources of the enzyme followed by ovary, mucosal layer of jejunum and liver. With respect to units/gram tissue, liver followed by testis, colon and rectum mucosal layers, ovary and mucosa of jejunum exhibited highest activities. The results of this study will allow one to speculate on the involvement of rhodanese in several biochemical and physiological functions in different tissues and organs of this species.

Comparison of rhodanese distribution in different tissues of Japanese quail, partridge, and pigeon

Rhodanese (thiosulfate: cyanide sulfurtransferase, EC. 2.8.1.1) is a ubiquitous enzyme present in all living organisms, from bacteria to humans, and plays a central role in cyanide detoxification. The purpose of this investigation was to determine and compare the pattern of distribution of rhodanese in different tissues of adult Japanese quail, partridge, and pigeon. In the three species studied, rhodanese was present in all tissues albeit in different amounts. The highest activity of rhodanese in Japanese quail was observed in kidney and proventriculus followed by liver and heart. In partridge, the highest activity of the enzyme was observed in heart, kidney, and proventriculus. In pigeon, the highest activity of the enzyme was observed in liver, kidney, and heart. Inter-species differences were seen in the level of enzyme in different tissues. The results of this study may indicate the involvement of rhodanese in cyanide detoxification in tissues that have greater potential to be exposed to higher levels of cyanide and also involvement of rhodanese in functions other than cyanide detoxification in other tissues.

Effect of Anabolic Steroid Nandrolone Decanoate on the Properties of Certain Enzymes in the Heart, Liver, and Muscle of Rats, and their Effect on Rats' Cardiac Electrophysiology

Nandrolone decanoate (ND) is an anabolic steroid, modified to enhance anabolic rather than androgenic actions. The physiological effects of ND treatment are often used in various aspects of medical practice. In this investigation we have tried to establish whether a single, high dose of ND (20 mg/kg) would cause any anabolic effects. Moreover, we have attempted to correlate the eventual effects with changes in the activity and kinetic properties of anabolic- and bioenergetic-involved enzymes in different tissues of rats, along with the rats' ECG parameters. The body and liver weights of the rats were unchanged, but heart weight had increased 10 days after ND injection. Electrocardiographic data showed a small prolongation of the QRS complex 3, 6, and 10 days after ND treatment. It was established that ND causes activation of glucose-6-phosphate and 6-phosphogluconate dehydrogenases, malic enzyme, and NADP-linked isocitrate dehydrogenase in rat hearts. Moreover, 6-phosphogluconate dehydrogenase from the hearts of ND-treated rats showed higher affinity to its substrate, in comparison with control. Activation of transketolase by ND in the liver was accompanied by inhibition of glucose-6-phosphate and 6-phosphogluconate dehydrogenases. We observed an increase of glucose 6-phosphate dehydrogenase and NAD-linked malate dehydrogenase in the muscle of ND treated rats. It may be concluded that ND in a single high dose exhibits cardiotrophic action, especially towards the increase of heart dehydrogenases activity which generates NADPH and supplies ribose phosphate for the biosynthesis of nucleotides and nucleic acids. On the other hand, ND may cause activation of ATP synthesis in muscle by enhanced malate-aspartate shuttle action.

Statistical evaluation of the isoform patterns of N-acetyl-β-hexosaminidase from human renal cancer tissue separated by isoelectrofocusing

Objectives Isoenzymes of HEX from human renal carcinoma and neighbouring macroscopically normal renal tissue can show different patterns on isoelectrofocusing gels. The aim of our work was to elaborate the method for statistical evaluation of differences. Design and methods Isoenzymes of N-acetyl-β-hexosaminidase were separated from renal (control and cancerous) tissues of 15 patients. Isoenzymes were electrofocused in Multiphor II, with ampholine pH 3.5–9.0 (2%) and then evaluated densitometrically and analysed statistically. Results A similar pattern in activity of isoforms of isoenzymes A and B in normal and cancerous renal tissue was observed. Conclusions The proposed method of statistical evaluation of differences in isoforms of N-acetyl-β-glucosaminidase can also be adapted to estimate the isoforms of other enzymes in different tissues.

Identification and Characterization of a Gene Encoding Human LPGAT1, an Endoplasmic Reticulum-associated Lysophosphatidylglycerol Acyltransferase

Phosphatidylglycerol (PG) is an important membrane polyglycerolphospholipid required for the activity of a variety of enzymes and is a precursor for synthesis of cardiolipin and bis(monoacylglycerol) phosphate. PG is subjected to remodeling subsequent to its de novo biosynthesis to incorporate appropriate acyl content for its biological functions and to prevent the harmful effect of lysophosphatidylglycerol (LPG) accumulation. The enzymes involved in the remodeling process have not yet been identified. We report here the identification and characterization of a human gene encoding an acyl-CoA: lysophosphatidylglycerol acyltransferase (LPGAT1). Expression of the LPGAT1 cDNA in Sf9 insect and COS-7 cells led to a significant increase in LPG acyltransferase activity. In contrast, no significant acyltransferase activities were detected against glycerol 3-phosphate or a variety of lysophospholipids, including lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylinositol, and lysophosphatidylserine. The recombinant human LPGAT1 enzyme recognized various acyl-CoAs and LPGs as substrates but demonstrated clear preference to long chain saturated fatty acyl-CoAs and oleoyl-CoA as acyl donors, which is consistent with the lipid composition of endogenous PGs identified from different tissues. Kinetic analyses of LPGAT1 expressed in COS-7 cells showed that oleoyl-LPG was preferred over palmitoyl-LPG as an acyl receptor, whereas oleoyl-CoA was preferred over lauroyl-CoA as an acyl donor. Consistent with its proposed microsomal origin, LPGAT1 was localized to the endoplasmic reticulum by subcellular fractionation and immunohistochemical analyses. Northern blot analysis indicated that the human LPGAT1 was widely distributed, suggesting a dynamic functional role of the enzyme in different tissues.

The role of bacterial antizyme: From an inhibitory protein to AtoC transcriptional regulator

This review considers the role of bacterial antizyme in the regulation of polyamine biosynthesis and gives new perspectives on the involvement of antizyme in other significant cellular mechanisms. Antizyme is a protein molecule induced by the end product of the enzymic reaction that it inhibits, in a non-competitive manner. The bacterial ornithine decarboxylase is regulated by nucleotides, phosphorylation and antizyme. The inhibition of ornithine decarboxylase by antizyme can be relieved to different degrees by DNA or by a variety of synthetic nucleic acid polymers, attributed to a specific interaction between nucleic acid and antizyme. Recently, this interplay between bacterial antizyme and nucleic acid was determined by discerning an additional function to antizyme that proved to be the atoC gene product, encoding the response regulator of the bacterial two-component system AtoS-AtoC. The gene located just upstream of atoC encodes the sensor kinase, named AtoS, that modulates AtoC activity. AtoC regulates expression of atoDAEB operon which is involved in short-chain fatty acid metabolism. Antizyme is thus referred to as AtoC, functioning both as a post-translational and transcriptional regulator. Also, the AtoS-AtoC signal transduction system in E. coli has a positive regulatory role on poly-(R)-3-hydroxybutyrate biosynthesis. The properties and gene structural similarities of antizymes from different organisms were compared. It was revealed that conserved domains are present mostly in the C-domain of all antizymes. BLAST analysis of the E. coli antizyme protein (AtoC) showed similarities around 69–58% among proteobacteria, g-proteobacteria, enterobacteria and the thermophilic bacterium Thermus thermophilus. A working hypothesis is proposed for the metabolic role of antizyme (AtoC) describing the significant biological implications of this protein molecule. Whether antizymes exist to other enzymes in different tissues, meeting the criteria discussed in the text remains to be elucidated.

Chitin metabolism in insects: structure, function and regulation of chitin synthases and chitinases.

Chitin is one of the most important biopolymers in nature. It is mainly produced by fungi, arthropods and nematodes. In insects, it functions as scaffold material, supporting the cuticles of the epidermis and trachea as well as the peritrophic matrices lining the gut epithelium. Insect growth and morphogenesis are strictly dependent on the capability to remodel chitin-containing structures. For this purpose, insects repeatedly produce chitin synthases and chitinolytic enzymes in different tissues. Coordination of chitin synthesis and its degradation requires strict control of the participating enzymes during development. In this review, we will summarize recent advances in understanding chitin synthesis and its degradation in insects.

Activities of xanthine oxidoreductase and antioxidant enzymes in different tissues of diabetic rats

Oxidative stress is an important pathogenic constituent in diabetic endothelial dysfunction. The aim of this study was to investigate whether an increase in oxidative stress related to xanthine oxidoreductase occurs in diabetes. Liver, brain, heart, and kidney xanthine oxidase (XO), xanthine dehydrogenase (XDH), antioxidant enzymes (glutathione peroxidase, superoxide dismutase, catalase), and nitrite levels were measured in control and early and late diabetic rat models. Although diabetes had no impact on liver XO and XDH activity, XDH activity in heart, kidney, and brain was significantly greater in late diabetic rats than in controls. Selenium glutathione peroxidase (GPx) activity was found to be lower in the liver, brain, kidney, and heart of late diabetic rats than in controls. The measured decrease in selenium GPx activity was also observed in early diabetic heart, kidney, and brain. No significant change was observed in liver, brain, and kidney copper/zinc superoxide dismutase (Cu/Zn SOD) activity in early and late diabetic rat models compared with that in controls, whereas heart Cu/Zn SOD activity was significantly decreased in both early and late diabetic rats. Liver and brain catalase activity remained similar among the different experimental groups, whereas increased heart and kidney catalase activity was observed in both early and late diabetic rats. Liver, kidney, and brain nitrite levels were found to be increased in early diabetic rat models compared with those in controls. These data suggest that the increased XDH and decreased selenium GPx activity observed in the later stages of diabetes leads to enhanced oxidative stress in the heart, kidney, and brain, resulting in secondary organ damage associated with the disease.

The effect of benzene on serum hormones and the activity of some enzymes in different tissues of rats

The effects of a 100 mg.kg -1 dose of benzene, an occupational and environmental toxicant, were investigated on serum, estradiol and testosterone concentrations as well as lactate dehydrogenase (LDH), alkaline phosphatase (ALP), alanine amino transferase (ALT), aspartate amino transferase (AST), and pyruvate kinase (PK) activities in the liver and kidney of rats after 2, 4, 8, 16, 32, 64 and 72 hours. Benzene was given intraperitoneally to Rat rattus norvegicus and the control groups were injected with physiological saline. Liver tissue LDH, AST, ALT and kidney tissue LDH, ALP, AST, ALT activities were lower in the benzene treated group when compared to those in the control group (p<0.05). A tendency for an increase in the liver tissue ALP activity was observed, which was significant at 8 and 16 hours (p<0.05). There were significant increases in ALT in the liver and LDH, AST, and ALT enzyme activities in the kidney tissue at the beginning of the experiment in both groups and these activities were found to be nearly the same. Pyruvate kinase enzyme activities in rats given benzene were slightly increased in kidney tissues but lower in liver tissues. Differences between the groups tended to disappear towards the end of the experimental period. However, serum estradiol concentrations in the serum diverged significantly (p<0.05). Consequently, it was found that benzene administration led to some changes (increases then decreases) in LDH, ALP, ALT, AST, and PK activity and estradiol, testosterone concentrations in different tissues of rats. Possible causes of the increases and decreases in enzyme activities and hormone levels are discussed.

Water content, body weight and acid mucopolysaccharides, hyaluronidase and β-glucuronidase in response to aestivation in Australian desert frogs

This study investigates the effects of aestivation on body water content, body mass, acid mucopolysaccharide (AMPS) and some of its degrading enzymes in different tissues for some Australian desert frogs. The AMPS component of the liver, kidney, skin and cocoon alter during aestivation to help retain water, which is unchanged in most tissues of all frog species, and to protect the frogs from desiccation during extended periods of aestivation. Hepatic AMPS was unaltered in Cyclorana maini, C. platycephala and Neobatrachus sutor but increased significantly after 2 months of aestivation in C. australis. The level of AMPS in the kidney was elevated in all four frog species after 5 months of aestivation. Skin AMPS content in the skin of awake frogs decreases with aestivation period and increases in the cocoon. AMPS in the cocoon probably works as a cement between the cocoons’ layers and its physical presence presumably contributes to preventing water flux. Changes in AMPS content in different tissues were accompanied by significant changes in both hyaluronidase and β-glucuronidase activities, which play an important role in AMPS metabolism. Alcian blue staining of control and digested skin of C. australis and C. platycephala with testicular hyaluronidase indicated the presence of AMPS, concentrated in a thin layer (called ground substance, GS) located between stratum compactum and stratum spongiosum, and acid mucin concentrated in the mucous glands and in a ‘tubular’ structure which could be observed in the epidermal layer. Hyaluronidase digestion of the cocoon slightly changed the Alcian Blue colour, suggesting the presence of a large amount of acid mucin similar to that found in the skin mucous gland. The results of this study present data for the redistribution of AMPS, which may help in reducing water loss across the cocoon and reabsorption of water in the kidney during aestivation.

Changes in the activities of selected enzymes in different tissues of sheep at different prenatal stages

Changes in the activities of selected enzymes in different tissues of sheep at different prenatal stages

Reversibility of H+-ATPase and H+-pyrophosphatase in tonoplast vesicles from maize coleoptiles and seeds

Tonoplast-enriched vesicles isolated from maize (Zea mays L.) coleoptiles and seeds synthesize ATP from ADP and inorganic phosphate (Pi) and inorganic pyrophosphate from Pi. The synthesis is consistent with reversal of the catalytic cycle of the H+-ATPase and H+-pyrophosphatase (PPase) vacuolar membrane-bound enzymes. This was monitored by measuring the exchange reaction that leads to 32Pi incorporation into ATP or inorganic pyrophosphate. The reversal reactions of these enzymes were dependent on the proton gradient formed across the vesicle membrane and were susceptible to the uncoupler carbonyl cyanide p(trifluoromethoxy)-phenylhydrazone and the detergent Triton X-100. Comparison of the two H+ pumps showed that the H+-ATPase was more active than H+-PPase in coleoptile tonoplast vesicles, whereas in seed vesicles H+-PPase activity was clearly dominant. These findings may reflect the physiological significance of these enzymes in different tissues at different stages of development and/or differentiation.

Modulations in antioxidant enzymes in different tissues of marine bivalve Perna viridis during heavy metal exposure.

Lipid peroxidation induced by metals at sub-lethal levels, alter physiological and biochemical characteristics of biological systems. To counter the detrimental effects of the prooxidant activity of metals, a group of antioxidant enzyme systems function in the organisms. The present study was performed to investigate into the lipid peroxidation product formation due to the exposure to effects of the metals namely aluminium, lead and cadmium at sub-lethal concentrations and the biological response through protective antioxidant enzyme activity in the marine mussels, Perna viridis Lin.. This organism is a known bioindicator and bioconcentrator of metals in the environment. The results of the present study were: (a) accumulation of lead showed a definite linear increase during the period of exposure whereas aluminium and cadmium showed fluctuations. Mantle and gill tissues showed greater accumulation of metals when compared to digestive gland; (b) lead and aluminium induced lipid peroxidation was greater in tissues than the peroxidation induced by cadmium. Cadmium induced peroxidation was observed only after the day 7 of the exposure; (c) anti-oxidant enzymes activity levels were significantly higher in digestive gland and mantle than gills; (d) mantle was observed to significantly contribute to the organismal response to lipid peroxidation as indicated by high activity levels of anti-oxidant enzymes.

Glycogen phosphorylase: control by phosphorylation and allosteric effectors.

Structural studies of muscle glycogen phosphorylase during the last two decades have provided a detailed mechanism for the molecular basis of the control by phosphorylation and by allosteric effectors and the catalytic mechanism. Control by phosphorylation is effected by a disorder to order transition of the NH2-terminal residues that promotes localized changes in the structure of the protein at the region of subunit-subunit contacts and larger changes in the quaternary structure. The covalently attached phosphate group acts like an allosteric effector but the full manifestation of the response is also dependent on the NH2-terminal tail residues. The noncovalently bound allosteric effectors produce similar shifts in the structural states although these are bound at sites that are remote from the serine-phosphate site. The communication from these sites to the catalytic site is through long-range interactions that result in activation of the enzyme through opening access to the buried catalytic site and through creation of the substrate phosphate recognition site by an interchange of an acidic group with a basic group. Recent advances in expression systems have opened the way to a study of properties both for the muscle and other isozymes and other species that should illuminate the different regulatory roles of the enzyme in different tissues and organisms. The allosteric mechanism of activation of phosphorylase by phosphorylation may be relevant to other enzymes although it is now known that other mechanisms such as electrostatic steric blocking mechanisms also exist.

Compartmentation of Animal Enzymes: Physiological and Evolutionary Significance

Many enzymes of animals, especially enzymes that regulate metabolic pathways, exhibit one or more types of inter - and intracellular compartmentation. A given type of catalytic activity is effected by different isoforms (isozymes) of a class of enzyme in different tissues, cells, or organelles, and many enzymes alter their locations within the cell under different physiological conditions. These compartmentation properties reflect major features of animal organization and function, e.g. , the occurrence of different metabolic tasks in different tissues or cellular compartments, and enormous changes in muscle metabolic rate during intense locomotion. Enzymes of glycolysis, notably phosphofructokinase (PFK) and hexokinase (HK), manifest these forms of compartmentation. PFK occurs in several isozyme forms that differ in kinetic properties. Skeletal muscle PFK binds reversibly to actin in a pH-dependent manner. Binding of PFK to actin affects the enzyme's catalytic activity, sensitivity to regulatory modulators, and structural stability in the face of decreasing intracellular pH (pHi). Eucaryotic PFKs arose from a gene duplication/fusion event of an ancestral procaryotic PFK. This increase in subunit mass from 36 kDa to 82 kDa in animal PFKs facilitated the evolution of additional regulatory sites and, we hypothesize, an actin binding capacity which varies among PFK isoforms. In vertebrates, hexokinase occurs in several isoforms that differ in kinetic properties and ability to bind to the outer surface of the mitochondrion. Binding of HK to mitochondria plays an important role in regulating glucose metabolism in glucose-dependent tissues like brain. The different abilities of vertebrate HK isozymes to bind to mitochondria are due to charge differences on the isozymes' surfaces. Invertebrate HKs are smaller than vertebrate HKs ( ca . 50 kDa vs . 100 kDa), and cannot bind to mitochondria. The evolution of multiple isozyme forms of animal enzymes, and the evolution of capacities for reversible intracellular compartmentation through increases in protein size, are discussed in the context of the large genome sizes characteristic of most animals

The role of mRNA levels and cellular localization in controlling sn-glycerol-3-phosphate dehydrogenase expression in tissues of the mouse.

sn-Glycerol-3-phosphate dehydrogenase (glycerol-P dehydrogenase, EC 1.1.1.8) activity levels in seven tissues of adult mice vary approximately 100-fold from a low of 0.1 unit/mg of protein in the cerebral cortex to a high of 8 units/mg of protein in the brown fat of cold-adapted mice; the brown fat accounts for approximately 1% of the total tissue protein. This high degree of variation in the quantitative expression of an enzyme in different tissues has provided us with a system for analyzing the mechanism by which tissue specific variation for a given gene product is controlled. To this end we have measured the amount of immunoreactive enzyme and the level of translatable glycerol-P dehydrogenase mRNA and have localized the glycerol-P dehydrogenase-positive cells by immunocytochemistry. We have found that the amount of enzyme protein in a tissue is strongly correlated with the level of its translatable mRNA (correlation coefficient = 0.996) and that in several cases the differences among tissues can be explained by differences in the numbers of glycerol-P dehydrogenase-positive cells.

Catalase, glutathione peroxidase and superoxide dismutase in different fish species

1. 1. The activities of catalase, glutathione peroxidase and superoxide dismutase were determined in extracts from nine different species of fish. 2. 2. The localization of these enzymes in different tissues were determined in saithe and mackerel. 3. 3. A relationship seems to exist between the levels of glutathione peroxidase and superoxide dismutase and the content of methionine sulphoxide in samples of fish kept in cold storage.