多酚与肌原纤维蛋白互作对蛋白质性能的影响

本文综述了近年来国内外关于茶多酚与蛋白质的相互作用方式,研究了茶多酚与肌原纤维蛋白相互作用的作用机理,以及在肉制品中加入多酚后,多酚与肌原纤维蛋白互作对蛋白质性能的影响,以期为减缓肉制品腐败变质提供参考。

“纳米沟壑”状PVDF多孔纳米纤维蛋白质吸附性能研究

以静电纺丝技术结合固相分离法,以PVDF为主体,分别以PEG、PVB为造孔剂制备出兼具疏水性能和优异蛋白质吸附性能的多孔PVDF-G、PVDF-B纳米纤维膜,结果显示当造孔剂为PVB时,即“纳米沟壑”状PVDF-B多孔纳米纤维膜的力学性能最高可达7.12 MPa,其纤维“纳米沟壑”状多孔结构分布均匀,且水接触角为119.3°,纤维膜整体对牛血清白蛋白吸附性能高达325μg/cm^(2)。基于本研究开发的“纳米沟壑”状蛋白质吸附纳米纤维材料,将为后续开发高性能蛋白质提纯材料提供一种新思路,该项研究有望拓展静电纺有机纳米纤维在生物医药、疾病诊断、免疫检测等领域的应用范畴。

Antioxidant properties of wheat germ protein hydrolysates evaluated in vitro

Wheat germ protein hydrolysates were prepared by protease hydrolysis, ultrafiltration and dynamical adsorption of resin. The total amount of amino acids in 100 g wheat germ protein hydrolysates is 93.95 g. Wheat germ protein hydrolysates are primarily composed of 4 fractions: 17.78% in the relative molecular mass range of 115631512, 17.50% in 1512842, 27.38% in 842372 and 30.65% in 37276, respectively. The antioxidant properties of wheat germ protein hydrolysates were evaluated by using different antioxidant tests in vitro. 1.20 g/L wheat germ protein hydrolysates exhibit 78.75% inhibition of peroxidation in linolei acid system; and 1.6g/L wheat germ protein hydrolysates show 81.11% scavenging effect on the 1,1-diphenyl-2-picrylhrazyl radical. The reducing power of 2.50 g/L wheat germ protein hydrolysates is 0.84. Furthermore, the scavenging activity of 0.60 g/L wheat germ protein hydrolysates against superoxide radical is 75.40%; 0.50 g/L wheat germ protein hydrolysates exhibit 63.35% chelating effect on ferrous ion. These antioxidant activities of wheat germ protein hydrolsates increase with the increase of its concentration. Experimental results suggest that wheat germ protein hydrolysate is a suitable natural antioxidant rich in nutrition and nontoxic.

Homozygosity for Pro of p53 Arg72Pro as a potential risk factor for hepatocellular carcinoma in Chinese population

AIM: Codon 72 exon 4 polymorphism (Arg72Pro) of the p53 gene has been implicated in cancer risk. Our objective was to investigate the possible association between p53Arg72Pro polymorphism and susceptibility to hepatocellular carcinoma (HCC) among Chinese population.METHODS: The p53 Arg72Pro genotypes were determined by PCR-based restriction fragment length polymorphism (RFLP) analysis in 507 HCC cases and 541 controls. Odds ratios (ORs) for HCC and 95% confidence intervals (CIs)from unconditional logistic regression models were used to evaluate relative risks. Potential risk factors were included in the logistic regression models as covariates in the multivariate analyses on genotype and HCC.RESULTS: The frequencies for Pro and Arg alleles were 44.5%, 55.5% in HCC cases, and 40.3% and 59.7% in controls, respectively. The Pro allele was significantly associated with the presence of HCC (P = 0.05) and had a higher risk for HCC (OR = 1.19, 95% CI 1.00-1.41) as compared with the Arg allele. After adjusted for potential risk factors, Arg/Pro heterozygotes had an 1.21-fold increased risk (95% CI 0.82-1.78, P = 0.34) of HCC compared with Arg homozygotes, whereas the risk for Pro homozygotes was 1.79 (95% CI 1.06-3.01, P = 0.03) times higher than that for Arg homozygotes. Pro-allele carriers had a higher relative risk of HCC than the Arg-only carriers (adjusted OR = 1.33, 95% CI 0.92-1.92, P = 0.13), although the difference was not statistically significant.CONCLUSION: Homozygosity for Pro of p53 Arg72Pro is potentially one of the genetic risk factors for HCC in Chinese population. The p53 Arg72Pro polymorphism may be used as a stratification marker in screening individuals at a high risk of HCC.

Adsorption of Protein in the Expanded Bed

The influence of operation parameters on the adsorption performance of protein (bovin serum albumin, BSA) in an expanded bed was studied using Streamline diethyl aminoethyl (DEAE). The result of residence time distributions (RTD) and breakthrough curves showed that adsorption performance of the expanded bed could not be improved by increasing the flow velocity at the range from 16ml·min-1 to 26ml·min-1. The increase of protein concentration from 0.5 mg·ml to 2 mg·ml-1 resulted in poor adsorption performance. With increasing temperature from 5℃ to 30℃ and the sedimented bed height from 11.5cm to 22.5cm, the adsorption characteristics in the expanded bed were improved.

Glutamate dehydrogenase and Na^+-K^+ ATPase expression and growth response of Litopenaeus vannamei to different salinities and dietary protein levels

Improvement in the osmoregulation capacity via nutritional supplies is vitally important in shrimp aquaculture.The effects of dietary protein levels on the osmoregulation capacity of the Pacific white shrimp(L.vannamei) were investigated.This involved an examination of growth performance,glutamate dehydrogenase(GDH) and Na+-K+ ATPase mRNA expression,,and GDH activity in muscles and gills.Three experimental diets were formulated,containing 25%,40%,and 50% dietary protein,and fed to the shrimp at a salinity of 25.After 20 days,no significant difference was observed in weight gain,though GDH and Na+-K+ ATPase gene expression and GDH activity increased with higher dietary protein levels.Subsequently,shrimp fed diets with 25% and 50% dietary protein were transferred into tanks with salinities of 38 and 5,respectively,and sampled at weeks 1 and 2.Shrimp fed with 40% protein at 25 in salinity(optimal conditions) were used as a control.Regardless of the salinities,shrimp fed with 50% dietary protein had significantly higher growth performance than other diets;no significant differences were found in comparison with the control.Shrimp fed with 25% dietary protein and maintained at salinities of 38 and 5 had significantly lower weight gain values after 2 weeks.Ambient salinity change also stimulated the hepatosomatic index,which increased in the first week and then recovered to a relatively normal level,as in the control,after 2 weeks.These findings indicate that in white shrimp,the specific protein nutrient and energy demands related to ambient salinity change are associated with protein metabolism.Increased dietary protein level could improve the osmoregulation capacity of L.vannamei with more energy resources allocated to GDH activity and expression.

Performance of the Bean-protein Fiber

The methods in testing the bean-protein fiber and the standards used were simply introduced. The fiber's mechanical and chemical performances were further analyzed. And the correlative performance of the bean-protein fibers and other natural fibers have been compared, then full knowledge of the fiber's performance was concluded.

Monocyte chemotactic protein-1 and soluble adhesion molecules as possible prognostic markers of the efficacy of antiviral treatment in chronic hepatitis C

AIM:To explain the role of Monocyte chemotactic protein-1 (MCP-1) and soluble adhesion molecules in chronic hepatitis C during the treatment of interferon alpha (IFNα) 2 b and ribavirin (RBV). METHODS:Concentrations of MCP-1,soluble adhesion molecules intercellular adhesion molecule-1 (sICAM-1),sP- selectin,interleukin (IL) 6,and IL10 in serum were estimated in the group of 40 patients with chronic hepatitis C treated with IFNalpha2 b and RBV in 0,16,32,48 wk of the therapy, RESULTS:In chronic hepatitis C,before and during the treatment,the serum levels of MCP-1 and sP-selectin in responders were similar to those of healthy subjects.In non- responders (NR),MCP-1 increased in the course of IFNc^+RBV treatment,differences were statistically significant as compared to responders.MCP-1 correlated statistically with the activity of periportal inflammation (r=0.35,P<0.05) but not with staging of liver fibrosis,sICAM-1 positively correlated with inflammatory activity and fibrosis in NR.sP-selectin did not correlate with histological findings in the liver.The MCP-1 correlated with the soluble form of sP-selectin concentrations (r= 6,P<0.001) and with IL-10 level in NR (r=0.4,P<0.05).There was no correlation observed between the concentration of MCP-1 and sICAM-1,IL-6 during the treatment. CONCLUSION:MCP-1 concentration may be a prognostic marker of the efficacy of IFN+RBV therapy in patients with chronic hepatitis C.

Influence of Three Protein Sources on Performance of Grasscutters （Thryonomys swinderianus） Fed Diets with or without Fishmeal

An 8-week feeding trial was conducted to assess the effect of soybean meal （SBM）, groundnut meal （GNM） and blood meal （BM） addition in diets with or without （1%） fishmeal on the performance, N-digestibility and cost of production of growing grasscutters. Fifty-four grasscutters （9-week-old） of mixed sexes were randomly assigned to six dietary treatments, using a completely randomized design （CRD） in a 2 × 3 factorial arrangement, with three grasscutters per treatment and three replicates each. Treatments 1-3 （TI-T3） contained no fishmeal, whilst treatments 4-6 （T4-T6） had 1% fishmeal added. The diets were formulated to be isocaloric and isonitrogenous. N-digestibility was significantly high for SBM diets with or without fishmeal, 83.91% and 82.19%, respectively, followed by BM diets. Average daily gain （ADG） was significantly （P 〈 0.05） high （12.95 g） for BM diet without fishmeal. Feed cost per kg diet was the lowest （US$0.195） for the same BM diet. The results indicated that the inclusion of SBM and BM in the diet of grasscutters with or without 1% fishmeal could improve performance and it may be the most economical for feeding BM in the diet without fishmeal.

Effect of Acid Treatment on Interfacial and Foam Properties of Soy Proteins

The goal of the present work was to study the effects of acid treatment on the foaming properties of a soybean protein isolate （SPI） and its fractions, glycinin （11S） and β-conglycinin （7S）. The structural characteristics, interfacial properties, foaming capacity and stability of the treated proteins were studied. Results from surface hydrophobicity and differential scanning calorimetry （DSC） showed that the acid treatment caused the complete denaturation of 11S and a partial denaturation of 7S. This protein unfolding affected their interracial properties, which led to an improvement in the foaming properties of both protein fractions and isolate. Treated 7S showed the best behavior in the rearrangement process, probably due to its smaller size and its modified structural characteristics. All treated proteins showed stronger interracial films. The foams of treated proteins were destabilized mostly due to gravitational drainage rather than Ostwald ripening.

Compensatory growth response of rainbow trout Oncorhynchus mykiss Walbaum following short starvation periods

This sixty-day study was performed to determine the effects of short-term starvation and refeeding cycles on growth, feeding performances and body composition of rainbow trout （Oncorhynchus mykiss）. Three hundred trout fingerlings with an average initial weight of 17.54-0.06 g were randomly distributed in 15 circular fiberglass tanks. The fish were exposed to 5 different feeding regimes; control： continuously fed twice daily to apparent satiation; T1： starved for 1 day and re-fed for 2 days; T2： starved for 1 day and re-fed for 4 days; T3： starved for 3 days and re-fed for 12 days; T4： starved for 4 days and re-fed for 16 days. At the end of the experiment, growth performance, feed utilization, whole body ash and moisture contents were not significantly （P〉0.05） different among the treatments. However, whole body protein content in T3 was significantly higher than other treatments （P〈0.05）. A significant difference in whole body fat content was observed between T3 and the control group at the end of the experiment （P〈0.05）. In conclusion this experiment suggests that feeding schedules involving starvation （1-4 days） and re-feeding cycles are a promising feed management tool for rainbow trout culture.

Effect of Some Processing Variables on the Quality Attributes of Yam Flour

The effect of varied processing variables （yam slice thickness, drying temperatures and type of drying） were investigated to determine their effects on the proximate and some functional properties of yam flour. The yam flour was produced with different slice thickness of 1, 1.5, 2.0, 2.5 and 5 cm using both conventional sun drying method and oven drying at temperatures; 40 ~C, 50 ~C, 60 ~C and 70 ~C. The moisture content of all the yam flour samples increased with increasing yam slice thickness, with the samples sun dried having the lowest values （6.20%-6.87%） followed by those dried at 70 ~C and then 60 ~C. The protein content of the yam flour samples increased with increase in slice thickness and decreased with increase in drying temperatures while the fat and the crude fibre of all the yam flour samples decreased with increase in slice thickness. The water absorption capacity of the sun dried yam flour samples decreased with increase in slice thickness while the syneresis value, bulk density and the gel strength increased with increase in slice thickness for all drying temperatures and for sun dried yam flour samples but smaller slice thickness had higher swelling capacity.

The conserved ubiquitin-like protein Hub1 plays a critical role in splicing in human cells

Different from canonical ubiquitin-like proteins, Hub1 does not form covalent conjugates with substrates but binds proteins noncovalently. In Socchoromyces cerevisioe, Hub1 associates with spUceosomes and mediates alternative splicing of SRCI, without affecting pre-mRNA splicing generaity. Human Hub1 is highty similar to its yeast homotog, but its cellular function remains largely unexplored. Here, we show that human Hub1 binds to the spliceosomal protein Snu66 as in yeast; however, unlike its 5. cerevisioe homolos, human Hub1 is essential for viability. Prolonged in vivo depletion of human Hub1 leads to various cellular defects, including splicing speckle abnormalities, partial nuclear retention of mRNAs, mitotic catastrophe, and consequently cell death by apoptosis. Early consequences of Hub1 depletion are severe splicing defects, however, only for specific splice sites leading to exon skipping and intron retention. Thus, the ubiquitin-iike protein Hub1 is not a canonlcal spliceosomal factor needed generally for splicing, but rather a modulator of spliceosome performance and facilitator of alternative splicing.

Supramolecular protein glue to boost enzyme activity

Proteins possess many biological functions.However, they can easily degrade or aggregate, thus losing their bioactivity. Therefore, it is very important to develop materials capable of interacting with proteins and forming nanostructures for protein storage and delivery. In this study,we serendipitously found a novel peptide-based supramolecular protein glue(Nap-GFFYK(γE)2-NH2, compound 1) that could co-assemble with proteins into nanofibers and hydrogels. We found that compound 1 rapidly folded into a β-sheet conformation upon contact with many proteins but not with polymers. Total internal reflection fluorescence microscopy(TIRFM) images clearly show the formation of co-assembled nanofibers by proteins and the peptide. The supramolecular protein glue could improve the dispersion of enzymes(lipase and lysozyme) and therefore enhance their catalytic activity,especially at high temperatures. More importantly, the supramolecular protein glue could co-assemble with two enzymes, glucose oxidase/horseradish peroxidase(GOx/HRP)and GOx/cytochrome c(cyt c), to form nanofibers that significantly enhanced the catalytic activity of tandem enzymatic reactions. We envisioned the great potential of our supramolecular protein glue for protein storage, delivery, and bioactivity manipulation.

METHOD FOR QUICKLY INFERRING THE MECHANISMS OF LARGE-SCALE COMPLEX NETWORKS BASED ON THE CENSUS OF SUBGRAPH CONCENTRATIONS

A Mechanism-Inferring method of networks exploited from machine learning theory caneffectively evaluate the predicting performance of a network model.The existing method for inferringnetwork mechanisms based on a census of subgraph numbers has some drawbacks,especially the needfor a runtime increasing strongly with network size and network density.In this paper,an improvedmethod has been proposed by introducing a census algorithm of subgraph concentrations.Networkmechanism can be quickly inferred by the new method even though the network has large scale andhigh density.Therefore,the application perspective of mechanism-inferring method has been extendedinto the wider fields of large-scale complex networks.By applying the new method to a case of proteininteraction network,the authors obtain the same inferring result as the existing method,which approvesthe effectiveness of the method.

The principle of compromise in competition: exploring stability condition of protein folding

Thermodynamic hypothesis and kinetic stabil- ity are currently used to understand protein folding. The former assumes that free energy minimum is the exclusive dominant mechanism in most cases, while the latter shows that some proteins have even lower free energy in inter- mediate states and their native states are kinetically trapped in the higher free energy region. This article explores the stability condition of protein structures on the basis of our study of complex chemical systems. We believe that sep- arating one from another is not reasonable since they should be coupled, and protein structures should be dom- inated by at least two mechanisms resulting in different characteristic states. It is concluded that： （1） Structures of proteins are dynamic, showing multiple characteristic states emerging alternately and each dominated by a respective mechanism. （2） Compromise in competition of multiple dominant mechanisms might be the key to understanding the stability of protein structures. （3） The dynamic process of protein folding should be depicted through the time series of both its energetic and structural changes, which is much meaningful and applicable than the free energy landscape.

Immunological function of familial Mediterranean fever disease protein Pyrin

Pyrin,encoded by MEFV gene,is conserved in humans and mice.Mutations in the MEFV gene are associated with the human autoinflammatory disease familial Mediterranean fever(FMF).Pyrin can interact with the inflammasome adaptor ASC and induce inflammatory caspase-1 activation in monocytic cells,but the physiological function of Pyrin has been unknown for many years.Here we summarize previous studies of Pyrin function under the context of FMF and immunity,and discuss a recent study demonstrating that Pyrin forms an inflammasome complex for caspase-1 activation in innate immunity.Pyrin inflammasome detects inactivating modifications of host Rho GTPases by diverse bacterial toxins and infections,including Clostridium difficile glucosylating cytotoxin Tcd B,FIC-domain adenylyltransferase effectors from Vibrio parahaemolyticus and Histophilus somni,ADP-ribosylating Clostridium botulinum C3 toxin as well as Burkholderia cenocepacia infection.The mode of Pyrin action,i.e.,sensing pathogen virulence activity rather than directly recognizing a microbial molecule,represents a new paradigm in innate immunity.