Basic Polypeptides Research Articles

Binding of phytate to soybean protein during the heat treatment of soymilk and its effect on protein aggregation

To investigate the interactions between phytates and soybean proteins during heat treatment, as well as their effects on the heat-induced protein aggregation and the formation of soymilk protein particles, the amount of free phytate, calcium, and magnesium in both unheated and heated soymilk were measured by equilibrium dialysis. It was found that about one-third of the free phytate became attached to proteins and was transferred to the particulate protein fraction after heat treatment. By heating purified soy protein solutions, it was shown that the soy glycinin had considerably higher phytate-binding capacity than β-conglycinin and that the binding reaction only occurred when the glycinin was denatured by being either heated to a temperature higher than 75 °C or treated with urea and SDS. It was assumed that when soymilk was heated to high temperatures, there was a critical “opening period” when the compact structure of glycinin unfolded and dissociated into the basic and acidic polypeptides, with plenty of the inner basic amino acids exposed to the surface, which attracted phytate and other denatured negatively charged protein fractions. The competitive binding of phytate with the basic polypeptides inhibited the binding of α/α’ subunits and acidic polypeptides to some extent, resulting in a smaller ratio of particulate proteins. Phytate enhanced the solubility and inhibited the thermal aggregation of glycinin by increasing the negative charges on the protein surface.

Acidic polypeptides A1a, A3 and A4 of Gly m 6 (glycinin) are allergenic for piglets

Gly m 6 (glycinin) is one of the major antigenic proteins in soybeans responsible for transient hypersensitivity to soybean meal in weaned piglets. The globulin is a hexamer consisting of subunits containing basic and acidic polypeptides. Multiple acidic polypeptides have long been demonstrated to be allergens for humans and play a key role in the overall allergenicity of Gly m 6. To date, knowledge on the allergenicity of the acidic polypeptides for piglets is very limited. The purpose of this study was to identify the acidic polypeptides that were allergenic for piglets and to characterize these acidic polypeptides by ELISA, western blot, skin prick and basophile histamine release test. The IgG and IgE antibody binding capacities of the acidic polypeptides of Gly m 6 were determined using ELISA and western blot analysis with sera from Gly m 6 sensitized piglets. Skin prick test and basophile histamine release test were conducted to measure the effector cell response to the polypeptides. Specific IgG and IgE antibodies against A1a, A3 and A4 of Gly m 6 were identified in the sera of Gly m 6 sensitized piglets. Meanwhile, positive skin prick test and specific histamine release responses were also induced by the acidic polypeptide A1a, A3 and A4 of Gly m 6 from the basophiles of Gly m 6 sensitized piglets. The results demonstrate that the acidic polypeptide A1a, A3 and A4 of Gly m 6 are allergenic for piglets.

Study on Isolation and Raman Spectroscopy of Glycinin in Soybean Protein

The secondary structures of soybean glycinin was investigated by Raman spectroscopy and its acidic and basic polypeptides were isolated. The results showed that the secondary structures of glycinin were mainly composed of 21.51% α-helix, 41.62% β-sheet, 24.70% β-turn, and 12.18% random coil. For the disulfide bridge (—S—S—), the ratios were 34.8% gauche—gauche—gauche (g—g—g), 32.1% gauche—gauche—trans (g—g—t), and 33.1% trans-gauche-trans (t—g—t). The I850/I830 intensity ratio of glycinin Raman tyrosine doublet confirmed that the contents of the N-buried and N-exposed tyrosine residue were 14.1% and 85.9%, respectively. The typical acidic subunit A and basic subunit B were clearly separated by heat denaturation and reduction with β-mercaptoethanol, and their corresponding molecular masses were 42 and 38 ku, respectively. Raman spectroscopic analysis can be used to determine the secondary structural properties of glycinin. Further studies of the glycinin structures will be helpful for the utilization of soybean protein resources.Supported by Grain & Corn Engineering Technology Research Center, State Administration of Grain (GA2017004), Science and Technology Research Project of Henan (172102110205).

Antihypertensive Effect of Peptides from Sesame, Almond, and Pumpkin Seeds: In-silico and In-vivo Evaluation

Plant proteins are important functional ingredients in many processed food products. In particular, globular proteins from various sources play an important role in many food products. In the current study, 11S globulin protein from white sesame seeds, amandin protein from almond seeds, and cucurbitin protein from pumpkin seeds were extracted by means of ammonium sulfate precipitation and purified by anion-exchange chromatography on a DEAE-Sephadex column (20 × 30 cm). Amandin protein of almond and cucurbitin protein of pumpkin seeds both belong to the 11S globulin family. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of protein samples treated with reducing agents revealed that the isolated 11S globulin from white sesame seeds was composed of an acidic (30－33 kDa) and basic (20－24 kDa) polypeptide, amandin from almond seeds was composed of an acidic (40－42 kDa) and basic (15－20 kDa) polypeptide, and cucurbitin from pumpkin seeds was composed of an acidic (35－42 kDa) and basic (20－25 kDa) polypeptide. The alpha amylase-inhibiting activities of the three proteins was determined. Cucurbitin of pumpkin seeds had a greater alpha amylase inhibitory effect (－86%) than 11S globulin of sesame (82.6%) and amandin protein of almond seeds (76%). The antihypertensive effect of the three proteins was evaluated by a chrioallantoin membrane assay in chick embryos, which revealed that cucurbitin protein showed higher vasodilatation activity than the other two proteins.

Extracorporeal blood purification in refractory septic shock: A case study

Background : Systemic inflammatory states such as severe sepsis and septic shock result in immunologic disturbances with the release of numerous inflammatory mediators. The systemic inflammatory response, though a result of innate immunity, can become deleterious when excessive or uncontrolled, leading to the development of multi-organ failure syndrome and death. Extracorporeal blood purification therapies have been proposed to improve outcomes for patients with severe sepsis. These therapies are based on the principle that removal of inflammatory mediators or bacterial toxins (or both) from the blood will favorably modulate the host inflammatory response. Recently, significant technological progress has greatly broadened the spectrum of techniques available for blood purification. However, these techniques have not entered into mainstream clinical practice around the world. Hemoadsorption places sorbents in direct contact with blood via an extracorporeal circuit. Polymyxin B is a cyclic basic polypeptide that disrupts the permeability of the cell membrane of Gram-negative bacteria. Polymyxin B-immobilized polystyrene-derived fibres (Toramyxin, Toray Industries, Inc., Tokyo, Japan) have been developed for use in extracoporeal therapy as a means to remove endotoxin from the blood. There are not many studies showing the efficacy of extracorporeal blood purification in paediatric population in India or around the world. Methods : A six years old girl with Salmonella typhi sepsis was retrieved on day 6 of illness in a state of fluid refractory shock on ventilatory support with oxygenation index (OI) of 16.2 and Vasoactive Inotropic Score (VIS) after 2 hours of admission was 50 with a diastolic blood pressure (DBP) of 35mmHg. She had multi-organ dysfunction with SGOT 3745U/L, SGPT 1353U/L, Arterial Lactate 11mmol/L, Creatinine 1.0mg/dl, CRP 108mg/ dl, Bicytopenia - Platelet 56000/cu.mm, WBC 2200/cu.mm (with 76% Neutrophils). She was on appropriate antibiotics since past 2 days at the referral centre. Over a period of 24 hours, her VIS increased to 53 with Fluid Overload percent (FO%) reaching 12% and her kidney injury progressed to AKIN Stage 3. We started her on Continuous Veno-venous Hemo-diafiltration (CVVHDF) which resulted in improvement in her renal parameters, Creatinine 0.4mg/dl, but she continued to have very low DBP (30 -35mmHg) despite high VIS and her inflammatory markers increased CRP 132mg/dl, with persistent Bicytopenia - Platelet 23000/cu.mm, WBC 2700/cu.mm (with 80% Neutrophils). As the child was already on CRRT, a decision to start the child on extracorporeal blood purification using Toramyxin cartridge was made and initiated at 40 hours after admission and continued for 36 hours. Results : With this, the child showed improvement with VIS decreasing to 35 after twelve hours, 25 after thirty six hours and 11 after twelve hours of stopping extracorporeal blood purification. Her inflammatory markers decreased with CRP 90mg/L after twelve hours and 54mg/L twenty four hours later. Blood counts also improved with WBC rising to 9100 (80% Neutrophils) forty eight hours of starting hemoadsorption, while she received platelet transfusion for thrombocytopenia. Her OI also improved to 8.7 after forty eight hours. The patient was off inotropes within 72 hours of starting extracorporeal blood purification and was extubated within 96 hours. Conclusion : We conclude that the use of an extracorporeal blood purification device (Toramyxin) may have helped in the removal of circulating endotoxin by adsorption, thus preventing progression of the biological cascade of sepsis and resulted in improvement in our patient’s hemodynamic status and decrease in inflammatory response leading to clinical improvement. The major limitation of our report is our inability to measure endotoxin levels of our patient to demonstrate decrease in their level pre- and post- hemoadsorption. We also cannot comment on the efficacy of extracorporeal blood purification devices based on this single case. But we wish to emphasise that many new modalities exist in treatment of septic shock and can be considered when dealing with refractory septic shock.

Proteins in Relation to Vigor and Viability of White Lupin (Lupinus albus L.) Seed Stored for 26 Years.

The aim of the study was to evaluate the vigor and viability as well as to determine and compare the contents of selected protein fractions of white lupin (Lupinus albus L.) seeds stored for 26 years at temperatures of -14°C and +20°C. The seeds stored at -14°C germinated in 86.3%, while the seeds stored at +20°C did not germinate at all. The viability evaluation was confirmed by the measuring electroconductivity of seed exudates. In seeds stored at -14°C the contents of γ, δ, and β conglutin were 14, 4 and 69 mg g-1 fresh mass, respectively, while in seed stored at +20°C they were 15.5, 3, 65 mg g-1 fresh mass, respectively. One-dimensional electrophoresis of γ and δ conglutin fractions indicated the presence of several intense polypeptide bands with molecular weights from 23.0 to 10.3 kDa. Polypeptide bands with a molecular weight of 22.4 and 19.8 kDa exhibited almost two times higher expression in the seeds stored at -14°C compared to the seeds stored at +20°C. Electrophoresis revealed 310 protein spots on the maps generated for seeds stored at -14°C, and 228 spots for seeds stored at +20°C. In seeds stored at +20°C most polypeptide subunits had a pI ranging from 4.5 to 7 and a molecular weight of 10–97 kDa. The greatest differences in the contents of polypeptides between the analyzed variants was observed within the range of 20–45 kDa (-14°C: 175, +20°C: 115 protein spots) and within the range of 65–97 kDa (-14°C: 103, +20°C: 75 protein spots). In seeds stored at +20°C, a clear decline in basic (8–10 pI) polypeptides was observed. The study demonstrated that the polypeptides identified as γ and δ conglutins are probably closely related to vigor and viability of seeds.

Protein charge distribution in proteomes and its impact on translation.

As proteins are synthesized, the nascent polypeptide must pass through a negatively charged exit tunnel. During this stage, positively charged stretches can interact with the ribosome walls and slow the translation. Therefore, charged polypeptides may be important factors that affect protein expression. To determine the frequency and distribution of positively and negatively charged stretches in different proteomes, the net charge was calculated for every 30 consecutive amino acid residues, which corresponds to the length of the ribosome exit tunnel. The following annotated and reviewed proteins in the UniProt database (Swiss-Prot) were analyzed: 551,705 proteins from different organisms and a total of 180 million protein segments. We observed that there were more negative than positive stretches and that super-charged positive sequences (i.e., net charges ≥ 14) were underrepresented in the proteomes. Overall, the proteins were more positively charged at their N-termini and C-termini, and this feature was present in most organisms and subcellular localizations. To investigate whether the N-terminal charges affect the elongation rates, previously published ribosomal profiling data obtained from S. cerevisiae, without translation-interfering drugs, were analyzed. We observed a nonlinear effect of the charge on the ribosome occupancy in which values ≥ +5 and ≤ -6 showed increased and reduced ribosome densities, respectively. These groups also showed different distributions across 80S monosomes and polysomes. Basic polypeptides are more common within short proteins that are translated by monosomes, whereas negative stretches are more abundant in polysome-translated proteins. These findings suggest that the nascent peptide charge impacts translation and can be one of the factors that regulate translation efficiency and protein expression.

Applicative effect of glycinin basic polypeptide in fresh wet noodles and antifungal characteristics

We aimed to evaluate applicative effect of glycinin basic polypeptide (GBP) on fresh wet noodles during 5 days storage at 4 °C and to investigate its antifungal characteristics against Aspergillus niger (A. niger) and Penicillium sp.. GBP enhanced the sensory scores for fresh wet noodles and reduced the total plate count of fungi in a dose-dependent manner during storage. More than 2.0 mg/g GBP had well preservative effect on fresh wet noodles with 4 days shelf life at 4 °C. The inhibition zone diameters for A. niger and Penicillium sp. increased with increasing GBP concentration. The minimum inhibition concentrations of GBP against A. niger and Penicillium sp. were 2.0 and 1.5 mg/mL, respectively. GBP could effectively inhibit mycelial growth and spore germination of A. niger and Penicillium sp.. The ergosterol content (EC) in the fungal plasma membrane decreased with the increase in GBP concentration. What is more, EC of fungi with 2.4 mg/mL GBP had significant different from other concentrations of GBP (p < 0.05). Thus, GBP had remarkable antifungal effects by inhibiting growth of mycelium and spore germination, and disrupting the plasma membrane of fungi. GBP might be an alternative to synthetic antifungal preservatives in starchy food to extend shelf life.

Influence of extraction pH on the foaming, emulsification, oil-binding and visco-elastic properties of marama protein.

Marama bean protein, as extracted previously at pH 8, forms a viscous, adhesive and extensible dough. To obtain a protein isolate with optimum functional properties, protein extraction under slightly acidic conditions (pH 6) was investigated. Two-dimensional electrophoresis showed that pH 6 extracted marama protein lacked some basic 11S legumin polypeptides, present in pH 8 extracted protein. However, it additionally contained acidic high molecular weight polypeptides (∼180 kDa), which were disulfide crosslinked into larger proteins. pH 6 extracted marama proteins had similar emulsification properties to soy protein isolate and several times higher foaming capacity than pH 8 extracted protein, egg white and soy protein isolate. pH 6 extracted protein dough was more elastic than pH 8 extracted protein, approaching the elasticity of wheat gluten. Marama protein extracted at pH 6 has excellent food-type functional properties, probably because it lacks some 11S polypeptides but has additional high molecular weight proteins. © 2017 Society of Chemical Industry.

Role of Antihypertensive Peptides from Plant (sesame, almond and pumpkin) Seed Storage Protein

Proteins are a potential source of health-promoting biomolecules with medical, nutraceutical, and/or food applications. In particular, plant proteins, including globular proteins, represent important functional ingredients in many processed food products. Thus, the current study investigated and compared the antihypertensive properties of globulin, amandin, and cucurbitin proteins isolated from white sesame, almond, and pumpkin seeds, respectively. Extracted globulin, amandin, and cucurbitin proteins were shown to each comprise acidic and basic polypeptides of varying sizes (globulin polypeptides, 30－33 and 20－24 kDa, respectively; amandin polypeptides, 40－42 and 15－20 kDa, respectively; cucurbitin polypeptides, 35－42 and 20－25 kDa, respectively). The alpha amylase-inhibiting activity and resulting antihypertensive effects exhibited by the isolated 11S globulin, amandin, and cucurbitin polypeptides were characterized. Finally, the current study also reviewed current literature with regard to the properties of various peptides released by plant proteases, and their mitigating effects on disorders such as hypertension, diabetes, obesity, and cancer.

Antibacterial characteristics of glycinin basic polypeptide against Staphylococcus aureus.

This paper aims to study the antibacterial action of glycinin basic polypeptide (GBP) on Staphylococcus aureus (S. aureus). Herein, the minimum inhibitory concentration (MIC) of GBP against S. aureus was 0.2 mg/mL. Atomic force microscopy (AFM) imaging showed that GBP seriously damaged the morphology of the S. aureus cells. GBP (0.8 mg/mL) enhanced the relative release of β-galactosidase to 25.48% when compared to the control. The activity of the respiratory-chain dehydrogenase of S. aureus decreased with increasing GBP concentration. GBP could cause a leakage of intracellular substances. Additionally, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that S. aureus bacterial proteins decreased in response to the time period of treating the bacterial cells with GBP. These results indicate that GBP could remarkably inhibit S. aureus and is, therefore, a potential food preservative.

Effects of glycinin basic polypeptide on sensory and physicochemical properties of chilled pork.

Effects of glycinin basic polypeptide (GBP) on sensory and physicochemical properties of pork during chilled storage were investigated. Pork treated with GBP was analyzed periodically for sensory properties, pH, total volatile base nitrogen (TVB-N), α-thiobarbituric acid (TBA), and total viable count (TVC) values. Compared with controls, TBA values of pork treated with GBP did not change. TVB-N, pH, and TVC values of pork showed reductions with increasing concentrations of GBP during 8 days of storage. However, there were increases in sensory scores. TVC values of treated pork showed a positive linear relationship with both pH and TVB-N values. GBP at 0.16 and 0.20% efficiently inhibited bacterial growth, and enhanced chilled pork sensory scores. Therefore, GBP has potential as a pork biological preservative for extension of shelf life during chilled storage.

An Overlook to the Characteristics and Roles Played by Eotaxin Network in the Pathophysiology of Food Allergies: Allergic Asthma and Atopic Dermatitis.

Investigations revealed substantial parts accomplished by chemokines specifically eotaxins and their specific receptors. They are functionally involved in the modulation of the pathologic state of tissue inflammation which is as a result of allergic reactions. Chemokines as small proteins with approximately 8-10kDa molecular weight are considered and fit in the bigger family of cytokines, containing basic heparin-binding polypeptide mediators. Chemokines actively interfere in the processes of selective, oriented leukocyte (including eosinophil) recruitment. As eminent from their name, more specifically, eotaxins are specialized for eosinophils' oriented locomotion toward allergic inflamed regions. To date, three members are defined for eotaxin subfamily as follows: eotaxin-1 (CCL11), eotaxin-2 (CCL24), and eotaxin-3 (CCL26), all of them bind to and activate CCR3 but have a low level of homology and appear to exhibit different physiological potentials. Allergy is described as a clinical state in which a pathologic hypersensitivity reaction is always initiated throughout an immunologic mechanism; similar to other immunologic reactions, an allergic reaction could also either be antibody or cell mediated. This type of allergic reactions occurs in all age groups and damages several different organs, having a significant impact on the emotional and social health of patients and their families and relatives. Concerning introductory comments introduced above, the authors of the present review attempted to collect and provide the latest evidences and information regarding the correlation between expression of eotaxin family members and allergy, in a wider extent, in two important allergic disorders: atopic asthma (AA) and atopic dermatitis (AD). Overall, concerning the most recent articles published within the database in the life sciences literature regarding the fundamental role(s) played by eotaxins in the pathogenesis of AA and AD, the authors of the current article propose that eotaxins (CCL11, CCL24, and CCL26) play key role(s) during symptomatic inflammatory responses raised in response to allergic crisis of these two clinical states.

Molecular sled sequences are common in mammalian proteins.

Recent work revealed a new class of molecular machines called molecular sleds, which are small basic molecules that bind and slide along DNA with the ability to carry cargo along DNA. Here, we performed biochemical and single-molecule flow stretching assays to investigate the basis of sliding activity in molecular sleds. In particular, we identified the functional core of pVIc, the first molecular sled characterized; peptide functional groups that control sliding activity; and propose a model for the sliding activity of molecular sleds. We also observed widespread DNA binding and sliding activity among basic polypeptide sequences that implicate mammalian nuclear localization sequences and many cell penetrating peptides as molecular sleds. These basic protein motifs exhibit weak but physiologically relevant sequence-nonspecific DNA affinity. Our findings indicate that many mammalian proteins contain molecular sled sequences and suggest the possibility that substantial undiscovered sliding activity exists among nuclear mammalian proteins.

Cardiotoxin III suppresses the invasiveness of MDA-MB-231 cells by targeting proto-oncogene tyrosine-protein kinase Src and reversing mesenchymal-to-epithelial transition

ABSTRACTThe epithelial-to-mesenchymal transition is the first step required for breast cancer to initiate metastasis. The aberrant activation of proto-oncogene tyrosine-protein kinase Src regulates multiple functions during tumor progression. Cardiotoxin III, a basic polypeptide isolated from Naja naja atra venom, has been shown to exhibit anticancer activity; however, the effect of cardiotoxin III on the epithelial-to-mesenchymal transition of cancer cells remains elusive. Exposure of MDA-MB-231 cells to cardiotoxin III resulted in morphological changes and upregulation of E-cadherin with a concomitant decrease in N-cadherin and vimentin protein levels, resulting in the inhibition of cell migration and invasion. Cardiotoxin III induced downregulation of snail and slug expression. Simultaneously, cardiotoxin III suppressed Src phosphorylation and downstream activation of focal adhesion kinase, of the docking protein p130cas, and of paxillin. In addition, cardiotoxin III inhibited the phosphorylation of extracellular signal-regulated kinase and phosphatidylinositol 3-kinase. The Src specific inhibitor 4-amino-5-(4-chlorophenyl)-7-(dimethylethyl)pyrazolo[3,4-d]pyrimidine decreased in the phosphorylation and the expression changes of epithelial-to-mesenchymal transition markers in a similar way. Thus, cardiotoxin III has a novel anticancer effect by suppressing proto-oncogene tyrosine-protein kinase activity, reversing epithelial-to-mesenchymal transition.

Taiwan cobra cardiotoxin III suppresses EGF/EGFR-mediated epithelial-to-mesenchymal transition and invasion of human breast cancer MDA-MB-231 cells

Breast cancer is a highly malignant carcinoma and most deaths of breast cancer are caused by metastasis. The epithelial-to-mesenchymal transition (EMT) has emerged as a pivotal event in the development of the invasive and metastatic potentials of cancer progression. Epidermal growth factor (EGF) and its receptor, EGFR, play roles in cancer metastasis. CTX III, a basic polypeptide isolated from Naja naja atra venom, has been shown to exhibit anticancer activity; however, the effect of CTX III on the EMT of cancer cells remains elusive. CTX III treatment resulted in morphological changes from elongated and spindle shape to rounded and epithelial-like shape, induced upregulation of E-cadherin and concurrent downregulation of N-cadherin and Vimentin protein levels, corresponding to observed decreases in cell migration and invasion. CTX III treatment also decreased the expression of Snail and Twist in EGF-induced MDA-MB-231 cells. Concurrently, CTX III efficiently inhibited the EGFR phosphorylation and downstream activation of phosphatidylinositol 3-kinase (PI3K)/Akt and ERK1/2. The EGFR specific inhibitor AG1478 significantly suppressed ERK1/2 and Akt phosphorylation, cell migration and invasion, as well as the expressional changes associated with EMT markers in EGF-induced MDA-MB-231 cells. CTX III inhibitory effect on EGF-evoked invasion of MDA-MB-231 cells is mediated through suppressing EGF/EGFR activation and EMT process.

影响慢性肾脏病患者血清甲状旁腺素的相关因素分析

目的：甲状旁腺激素(parathyroid hormone, PTH)，是甲状旁腺主细胞分泌的碱性单链多肽类激素，在慢性肾病的并发症发病中日益显示其重要性。通过检测本肾病中心599例慢性肾病患者的PTH值，探讨不同阶段的慢性肾病PTH异常率的差异，并分析性别和年龄是否影响慢性肾病患者的PTH值。方法：利用化学发光免疫夹心法检测PTH浓度。结果：统计结果显示尿毒症患者组的PTH异常率显著高于非尿毒症患者组(P = 0.02)；男性尿毒症患者的PTH异常率明显高于女性尿毒症患者(P = 0.007)；尤其值得注意的是，无论是尿毒症组还是非尿毒症组，年龄 ≥ 50的慢性肾病患者PTH异常率比年龄 < 50的患者低，且在非尿毒症组具有显著性差异(P = 0.006)。结论：PTH异常与慢性肾脏病的恶化明显相关，年龄因素参与慢性肾病患者PTH调控的机理有待进一步阐明。 Objective: Parathyroid hormone (PTH), is a basic single chain polypeptide hormone secreted by parathyroid cells, has become increasingly important in the pathogenesis of chronic kidney disease. By testing the PTH value of 599 patients with chronic kidney disease (CKD), we investigate the dif-ference of PTH abnormal rate in different stages of chronic kidney disease, and analyze whether the gender and age affect the PTH value of patients with chronic kidney disease. Methods: The concen-tration of PTH was detected by chemiluminescence immunoassay. Results: Statistical results showed that the abnormal rate of PTH in uremic patients was significantly higher than that in non-uremic patients (P = 0.02). The abnormal rate of PTH in male uremic patients was significantly higher than that in female patients with uremia (P = 0.007). In particular, it was worth noting that, in both uremic group and non-uremic group, the PTH abnormal rate of the CKD patients aged ≥50 was lower than that of age < 50, and there was a significant difference in the non-uremic group (P = 0.006). Conclusion: PTH abnormalities were significantly correlated with the progression of chronic kidney disease, and the mechanism of PTH influenced by the age in CKD patients needed to be further clarified.

Secondary Structure and Subunit Composition of Soy Protein In Vitro Digested by Pepsin and Its Relation with Digestibility.

In the present study, in vitro digestibility and structure of soybean protein isolates (SPIs) prepared from five soybean varieties were investigated in simulated gastric fluid (SGF), using FT-IR microspectroscopy and SDS-PAGE. The result indicated that β-conformations were prone to be hydrolyzed by pepsin preferentially and transformed to unordered structure during in vitro digestion, followed by the digestion of α-helix and unordered structure. A negative linear correlation coefficient was found between the β-conformation contents of five SPIs and their in vitro digestibility values. The intensities of the protein bands corresponding to 7S and 11S fractions were decreased and many peptide bands appeared at 11~15 kDa during enzymatic hydrolysis. β-conglycinin was poorly hydrolyzed with pepsin, especially the β-7S subunit. On the other hand, basic polypeptides of glycinin degraded slower than acidic polypeptides and represented a large proportion of the residual protein after digestion. 11S-A3 of all SPIs disappeared after 1 h digestion. Moreover, a significant negative linear correlation coefficient (r = −0.89) was found between the β-7S contents of five SPIs and their in vitro digestibility values. These results are useful for further studies of the functional properties and bioactive properties of these varieties and laid theoretical foundations for the development of the specific functional soy protein isolate.

Interactions in casein micelle – Pea protein system (part I): Heat-induced denaturation and aggregation

The aim of this work was to investigate the heat-induced interactions between pea proteins (vicilin 7S or legumin 11S enriched-fractions) in admixture with suspended casein micelles (SCM), at weight protein ratio of 1:1 and pH 7.1. The single-protein samples and mixtures thereof were prepared at concentrations of 18 and 36 mgprotein/gsample, respectively, then heated from 40 to 85 °C and incubated for 0–60 min. As compared to single-protein samples, differential scanning calorimetry (DSC) data indicated that the denaturation temperature of pea proteins increased of about 4 °C in the presence of SCM. Heat-induced change in protein composition of the soluble (SP) and micellar (MP) phases from centrifuged SCM – pea protein mixture was assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and densitometry. Likewise SP was analyzed by size-exclusion chromatography (SEC-HPLC). While pea legumin 11S and vicilin 7S oligomers were markedly sedimentable in MP from their respective unheated mixture, thermal denaturation and protein aggregation (≥75 °C) resulted in increasing levels of dissolved pea proteins in SP. Heating of the SCM – legumin mixture (85 °C, 15–60 min incubation) resulted in the dissociation of the legumin subunits Lαβ into acidic Lα and basic Lβ polypeptides, yielding in comparable amounts soluble and insoluble disulfide-bonded aggregates, respectively. In contrast in the SCM – vicilin mixture, the heat-denatured vicilin polypeptides in a temperature range of 70–80 °C produced in majority soluble and non-covalent aggregates. Though the heat-induced interactions between pea proteins were altered in the presence of micelles, caseins would not be involved into pea proteins aggregation.

Anti-inflammatory Effects of Poly-L-lysine in Intestinal Mucosal System Mediated by Calcium-Sensing Receptor Activation.

Calcium-sensing receptor (CaSR) is involved in maintaining cellular homeostasis and promoting recovery of damaged intestinal epithelial cells (IECs). Poly-L-lysine (PL) is a basic polypeptide identified for its role in the activation of CaSR through allosteric binding. The primary goal of the current study was to identify the modulatory effect of PL on intestinal inflammation and to determine whether these effects were mediated by CaSR activation. We used human intestinal epithelial cell lines, Caco-2 and HT-29, to assess PL anti-inflammatory activities in vitro. We found that PL reduced the IL-8 secretion from tumor necrosis factor (TNF)-α-treated human intestinal epithelial cell lines. On the other hand, the gene expression of pro-inflammatory cytokines TNF-α, IL-6, and IL-1β was inhibited by PL supplementation. We subsequently evaluated the anti-inflammatory activity of PL in vivo using a DSS-induced mouse colitis model. PL supplementation was shown to prevent dextran sulfate sodium salt (DSS)-induced loss of weight, colitic symptoms, and shortening of colon length but maintained colonic morphology. The pro-inflammatory cytokine expression in the mouse colon, including TNF-α, IL-6, INF-γ, IL-17, and IL-1β, was significantly up-regulated by DSS treatment, but was inhibited upon PL administration. As shown by the results from both in vitro and in vivo studies, the reduction of inflammatory cytokine production caused by PL was reversed by NPS-2143 pretreatment. In the present study, we provide evidence that PL exerts anti-inflammatory effects on the gut system, which is primarily mediated by allosteric ligand activation of CaSR.