Considering calcium-binding proteins in invertebrates: multi-functional proteins that shape neuronal growth

Calcium is a critical second messenger molecule in all cells and is vital in neurons for synaptic transmission.Given this importance,calcium ions are tightly controlled by a host of molecular players including ion channels,sensors,and buffering proteins.Calcium can act directly by binding to signaling molecules or calcium’s effects can be indirect,for example by altering nuclear histones.

Molecular cloning and functional analysis of two calcium associated cuticular protein genes in Neocaridina denticulata sinensis

The body surface of crustaceans is covered with a sturdy shell.The growth and development of crustaceans are realized through molting.Neocaridina denticulata sinensis is a suitable candidate for crustacean scientific research.Two calcium-associated cuticular protein genes,named NdCAP-1 and NdCAP-2,were obtained from N.denticulata sinensis.Molecular docking simulated the binding effect of both proteins and calcium ions.Semi-quantitative reverse transcription PCR results show that NdCAP-1 is expressed in D_(2-4) stage,NdCAP-2 expressed in D_(2-4) and A-B stages,and both were significantly expressed in the cephalothorax cuticle and pereiopods.Then,it was revealed that NdCAP-1 and NdCAP-2 are regulated by NdEcR-mediated 20 E signaling pathways.Knockdown of NdCAP-1 and NdCAP-2 was observed to cause surface defects.The recombinant proteins(rNdCAP-1 and rNdCAP-2),obtained by prokaryotic expression,had calcium-binding and chitin-binding ability,inhibited formation of calcium carbonate precipitate.These results show that calcium-associated cuticular proteins play important roles in cuticle formation and calcification.

Glial fibrillary acidic protein levels are associated with global histone H4 acetylation after spinal cord injury in rats

Emerging evidence has suggested global histone H4 acetylation status plays an important role in neural plasticity. For instance, the imbalance of this epigenetic marker has been hypothesized as a key factor for the development and progression of several neurological diseases. Likewise, astrocytic reactivity-a wellknown process that markedly influences the tissue remodeling after a central nervous system injury-is crucial for tissue remodeling after spinal cord injury（SCI）. However, the linkage between the above-mentioned mechanisms after SCI remains poorly understood. We sought to investigate the relation between both glial fibrillary acidic protein（GFAP） and S100 calcium-binding protein B（S100B）（astrocytic reactivity classical markers） and global histone H4 acetylation levels. Sixty-one male Wistar rats（aged ~3 months） were divided into the following groups： sham; 6 hours post-SCI; 24 hours post-SCI; 48 hours post-SCI; 72 hours post-SCI; and 7 days post-SCI. The results suggested that GFAP, but not S100B was associated with global histone H4 acetylation levels. Moreover, global histone H4 acetylation levels exhibited a complex pattern after SCI, encompassing at least three clearly defined phases（first phase： no changes in the 6, 24 and 48 hours post-SCI groups; second phase： increased levels in the 72 hours post-SCI group; and a third phase： return to levels similar to control in the 7 days post-SCI group）. Overall, these findings suggest global H4 acetylation levels exhibit distinct patterns of expression during the first week post-SCI, which may be associated with GFAP levels in the perilesional tissue. Current data encourage studies using H4 acetylation as a possible biomarker for tissue remodeling after spinal cord injury.

Characteristic and effect analysis of protein and peptide in Cantonese cured meat processing

The aim of this work was to explore the physicochemical and structural properties,lipid oxidation and antioxidant capacity of the peptides extracted from Cantonese cured meat and as well as to investigate the effect of drying time on the sarcoplasmic and myofibrillar proteins of Cantonese cured meat.The results suggested that salting out,protein oxidation and heat treatment were closely related to surface hydrophobicity and the secondary structure of peptides was changed by processing.And the peroxide value and the value of tributyltin compounds were different in evaluating the degree of lipid oxidation.Glu and His were the major amino acid.The approximate molecular weights of the sarcoplasmic proteins and myofibrillar proteins ranged from 31 kDa to 50 kDa and 66 kDa,respectively.The results indicated that reducing the levels of protein oxidation and improvement of the antioxidant properties should be of great interest to preserve the nutritional quality of meat products and prolong preservation period.

虾肉蛋白在乳酸菌发酵过程中的降解及其体外抗氧化活性的动态变化

本实验探究了在乳酸肠球菌发酵过程中虾肉肌原纤维蛋白和肌浆蛋白的降解及其产物(肽)抗氧化活性变化。结果表明,与未发酵时相比,随发酵时间的延长,两种蛋白的pH值均显著下降(P<0.05),蛋白酶活力均显著升高(P<0.05)。凝胶电泳结果表明,发酵使两种蛋白质均发生了降解,其中肌浆蛋白的降解程度更为明显。发酵后两种蛋白体系的2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)(2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid),ABTS)阳离子自由基清除率、1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除率、Fe^(3+)还原力均显著增强(P<0.05),其中肌浆蛋白降解产物(肽)的抗氧化能力显著高于肌原纤维蛋白降解产物(P<0.05)。相关性分析显示,蛋白酶活力与肌浆蛋白的水解度及其产物的ABTS阳离子自由基清除率、DPPH自由基清除率以及Fe^(3+)还原能力呈显著正相关(P<0.05、P<0.01)。综上,通过乳酸肠球菌发酵虾肉蛋白,尤其是肌浆蛋白可得到具有较高抗氧化能力的肽。本研究可为水产加工(如鱼糜)过程中产生肌浆蛋白的充分利用和抗氧化活性肽的开发提供理论依据。

鲢鱼糜漂洗液中不同回收方式肌浆蛋白的结构和功能特性

以鲢鱼糜漂洗废液中的肌浆蛋白为对象,对比分析回收方式对肌浆蛋白的结构和功能特性的影响。结果表明:酸偏移和热处理对肌浆蛋白的巯基向二硫键转化程度、表面疏水性、色氨酸内源荧光光谱强度、溶解性、起泡性的影响较大;通过对肌浆蛋白二级结构分析发现,冷冻干燥和热处理法下β-折叠相对含量较大,等电点沉淀法、酸偏移法和酸偏移耦合壳聚糖絮凝法下无规则卷曲相对含量较大,壳聚糖絮凝法下β-转角相对含量较大,所有回收方式下α-螺旋相对含量均较小,总体上肌浆蛋白二级结构由有序向无序不同程度转化;此外,壳聚糖与肌浆蛋白结合,絮凝产生大分子复合物,而酸偏移导致部分蛋白解聚。不同回收方式下肌浆蛋白结构变化进而影响到功能性质,其中酸偏移耦合壳聚糖絮凝法制备的肌浆蛋白在pH值和壳聚糖双重作用下表面疏水性明显增加,促使乳化性降低;而经冷冻干燥、等电点沉淀法和壳聚糖絮凝回收得到肌浆蛋白的乳化性较大,特别是壳聚糖处理能有效改善肌浆蛋白的乳化性。

过敏原肌质钙结合蛋白在毕赤酵母中的表达、优化及免疫反应性研究

目的 利用毕赤酵母(Pichia pastoris, P. pastoris)高效表达三疣梭子蟹(Portunustrituberculatus)重要过敏原肌质钙结合蛋白(sarcoplasmic calcium binding protein, SCP),并检验其免疫反应性。方法 根据毕赤酵母的密码子偏好性优化SCP基因并构建重组质粒。将其热激转化至P. pastorisGS115菌株后经遗传霉素(geneticin,G418)筛选获得阳性高拷贝子。最后通过甲醇诱导表达重组SCP并结合免疫印记(western blotting,WB)和间接酶联免疫吸附实验(enzyme-linked immunosorbent assay, ELISA)验证其免疫反应性。结果 在摇瓶水平下,重组SCP在毕赤酵母中最佳的表达条件为:诱导温度为28℃,甲醇添加量为每24h添加1.0%甲醇,诱导pH为6.0,诱导时间为144 h。在此条件下, SCP(纯度为91.6%)的得率为1.5 mg/100 mL菌液,实现了可溶性高效表达。WB和间接ELISA结果表明,重组SCP具有免疫球蛋白G结合能力。结论 毕赤酵母表达系统可以得到纯度较高且免疫反应性良好的重组SCP。本研究可为SCP的理化研究及过敏原标准物质的应用奠定基础,并有望促进特异性甲壳类过敏原检测的发展。

超声波处理对类PSE鸡肉肌浆蛋白的结构性质和乳化性能影响

以类PSE(pale,soft and exudative)鸡肉肌浆蛋白为对象,探讨不同超声功率(20 kHz,0、150、300、450、600 W)在不同超声时间(0、5、10、15 min)条件下对肌浆蛋白的结构、理化性质以及乳化性能的影响。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳显示超声前后肌浆蛋白组成无明显变化;圆二色谱检测显示超声处理未改变类PSE鸡肉肌浆蛋白的二级结构。不同超声时间(5~15 min)和不同超声功率(150~600 W)处理对肌浆蛋白的粒径、浊度、电位、表面疏水性、荧光强度、紫外光谱、溶解度、乳化性能等均有显著影响。随超声处理时间的延长,超声处理功率的增加,类PSE鸡肉肌浆蛋白的平均粒径与浊度显著减小(P<0.05),最低降至粒径237.2 nm和浊度0.018;Zeta电位绝对值、溶解度、表面疏水性和荧光强度显著增加;以上指标均在超声时间相同条件下超声功率达到600 W时或超声功率相同条件下超声时间延长至15 min时,效果最显著,其中相比于对照组溶解度最大增加了44.72%。另外,超声处理可显著增加类PSE鸡肉肌浆蛋白的乳化活性指数和乳化稳定性指数,降低肌浆蛋白乳液稳定性指数(P<0.05),其中20 kHz、300 W超声处理15 min时类PSE肌浆蛋白乳化性能最高,乳化活性指数增加了79.18%,乳化稳定性指数增加了44.87%。综上,超声处理改变了类PSE鸡肉肌浆蛋白的结构性质,有效改善了其溶解性与乳化性能。

Diagnostic and Predictive Levels of Calcium-binding Protein A8 and Tumor Necrosis Factor Receptor-associated Factor 6 in Sepsis-associated Encephalopathy： A Prospective Observational Study

Background： Despite its high prevalence, morbidity, and mortality, sepsis-associated encephalopathy （SAE） is still poorly understood. The aim of this prospective and observational study was to investigate the clinical significance of calcium-binding protein A8 （S 100AS） in serum and tumor necrosis factor receptor-associated factor 6 （TRAF6） in peripheral blood mononuclear cells （PBMCs） in diagnosing SAE and predicting its prognosis. Methods： Data of septic patients were collected within 24 h after Intensive Care Unit admission fi-om July 2014 to March 2015. Healthy medical personnel served as the control group. SAE was defined as cerebral dysfhnction in the presence of sepsis that fulfilled the exclusion criteria. The biochemical indicators, Glasgow Coma Scale, Acute Physiology and Chronic Health Evaluation score II, TRAF6 in PBMC, serum S 100A8, S 10013, and neuron-specific enolase were evaluated in SAE patients afresh. TRAF6 and S 100A8 were also measured in the control group. Results： Of the 57 enrolled patients, 29 were diagnosed with SAE. The S 100A8 and TRAF6 concentrations in SAE patients were both significantly higher than that in no-encephalopathy （NE） patients, and higher in NE than that in controls （3.74 ± 3.13 vs. 1.08 ± 0.75 vs. 0.37 ± 0.14 ng/ml, P 〈 0.01 ; 3.18 ± 1.55 vs. 1.02 ± 0.63 vs. 0.47 ± 0.10, P 〈 0.01）. S 100A8 levels of 1.93 ng/ml were diagnostic of SAE with 92.90% specificity and 69.00% sensitivity in the receiver operating characteristic （ROC） curve, and the area under the curve was 0.86 （95% confidence interval [CI]： 0.76-0.95）. TRAF6-relative levels of 1.44 were diagnostic of SAE with 85.70% specificity and 86.20% sensitivity, and the area under the curve was 0.94 （95% CI： 0.88-0.99）. In addition, S 100A8 levels of 2.41 ng/ml predicted 28-day mortality of SAE with 90.00% specificity and 73.70% sensitivity in the ROC curve, and the area under the curve was 0.88. TRAF6 relative levels of 2.94 predicted 28-day mortality of SAE with 80.00% specificity and 68.40% sensitivity, and the area under the curve was 0.77. Compared with TRAF6, the specificity of serum S 100A8 in diagnosing SAE and predicting mortality was higher, although the sensitivity was low. In contrast, the TRAF6 had higher sensitivity for diagnosis. Conclusions： Peripheral blood levels of S 100A8 and TRAF6 in SAE patients were elevated and might be related to the severity of SAE and predict the outcome of SAE. The efficacy and specificity of S 100A8 for SAE diagnosis were superior, despite its weak sensitivity. S100A8 might be a better biomarker for diagnosis of SAE and predicting prognosis.

Co-existence of calcium-binding proteins and γ-aminobutyric acid or glycine in neurons of the rat medullary dorsal horn

Background We investigated the co-expression of calb indin-D28k (CB), calretinin (CR) and parvalbumin (PV, a combination of the three is referred to as CaBPs) with γ-aminobutyric acid (GABA) or glycine in neurons of the rat medullary dorsal horn (MDH).Methods Immunofluorescence histochemical double-staining for CaBPs and GABA or glycine was performed on the sections from rat MDH. Results CB-, CR-, PV-, GABA- and glycine-like immunoreactive (LI) neurons were differentially observed in all layers of the MDH, but particularly in lamina Ⅱ. Neurons that exhibited immunoreactivity for both CaBPs and GABA or glycine were also observed mainly in lamina Ⅱ. A few of them were found in laminae I and III. The percentages of neurons which co-expressed CB/GABA or CB/glycine out of the total numbers of CB- and GABA-LI neurons or CB- and glycine-LI neurons were 5.3% and 12.1% or 4.1% and 10.0%, respectively. The ratios of CR/GABA or CR/glycine co-existing neurons out of the total numbers of CR- and GABA-LI neurons or CR- and glycine-LI neurons were 5.8% and 7.6% or 4.4% and 7.1%, respectively. The rates of PV/GABA or PV/glycine co-localized neurons out of the total numbers of PV- and GABA-LI neurons or PV- and glycine-LI neurons were 11.1% and 5.1% or 9.9% and 5.1%, respectively. Conclusion The results indicate that some neurons in the MDH contain both CaBPs and GABA or glycine.

超声波处理对类PSE鸡肉肌浆蛋白与肌原纤维蛋白复合凝胶特性的影响

以类PSE(pale,soft and exudative)鸡肉肌原纤维蛋白(myofibrillar protein,MP)和肌浆蛋白(sarcoplasmic protein,SP)为对象,首先研究类PSE鸡肉SP与MP不同比例(仅添加MP、1∶9、2∶8、3∶7(质量比))复合体系热诱导凝胶特性的变化,选择合适的SP和MP复合比例后进一步研究不同超声波功率处理(20 kHz,0、300、600 W)的SP与MP复合凝胶的凝胶特性、水分分布、分子间作用力、凝胶电泳和微观结构的变化。结果表明:与仅添加MP组相比,随着SP添加量增加,凝胶强度和保水性呈现先上升后下降的趋势,在添加比例为2∶8时达到最高;在SP与MP添加比例为2∶8、600 W超声波处理时,凝胶的凝胶强度和保水性与对照组相比分别升高了113%和47%。由十二烷基硫酸钠-聚丙烯酰胺凝胶电泳图谱可知,SP对肌球蛋白的聚集和交联有一定的促进作用,但在SP与MP添加比例为3∶7时,此效果变差。SP与MP添加比例为2∶8、超声波功率为600 W时,疏水相互作用以及二硫键的含量最高,复合凝胶的三维网络更均匀致密。综上,SP对类PSE鸡肉MP凝胶形成能力的影响与其添加量有关,超声波处理的SP有利于MP凝胶结构的形成,从而能够有效改善类PSE鸡肉MP的凝胶特性。

油酸对鲅鱼肌浆蛋白结构和理化特性的影响

为研究油酸(oleic acid,OA)对鲅鱼肌浆蛋白(sarcoplasmic proteins,SP)的诱导作用,采用不同浓度(0~40 mmol/L)的OA处理鲅鱼肌浆蛋白,分析对SP结构和理化特性的影响。结果表明,与对照组相比,随着OA浓度的升高,SP中羰基含量随之显著上升(P<0.05),总巯基含量随之显著下降(P<0.05);表面疏水性和傅里叶红外光谱研究发现,OA可以引起SP的疏水基团暴露和去折叠;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果反映出OA造成SP聚合物的形成,并通过内源荧光光谱分析发现OA引起SP二硫键交联;最终导致SP溶解度减小、浊度随之增大,说明OA影响SP结构并导致鲅鱼SP的聚集。

S100 calcium-binding protein A9 promotes skin regeneration through toll-like receptor 4 during tissue expansion

Background:In plastic surgery,tissue expansion is widely used for repairing skin defects.However,low expansion efficiency and skin rupture caused by thin,expanded skin remain significant challenges in promoting skin regeneration during expansion.S100 calcium-binding protein A9(S100A9)is essential in promoting wound healing;however,its effects on skin regeneration during tissue expansion remain unclear.The aim of the present study was to explore the role of S100A9 in skin regeneration,particularly collagen production to investigate its importance in skin regeneration during tissue expansion.Methods:The expression and distribution of S100A9 and its receptors-toll-like receptor 4(TLR-4)and receptor for advanced glycation end products were studied in expanded skin.These character-istics were investigated in skin samples of rats and patients.Moreover,the expression of S100A9 was investigated in stretched keratinocytes in vitro.The effects of S100A9 on the proliferation and migration of skin fibroblasts were also observed.TAK-242 was used to inhibit the binding of S100A9 to TLR-4;the levels of collagen I(COL I),transforming growth factor beta(TGF-β),TLR-4 and phospho-extracellular signal-related kinase 1/2(p-ERK1/2)in fibroblasts were determined.Furthermore,fibroblasts were co-cultured with stretched S100A9-knockout keratinocytes by siRNA transfection and the levels of COL I,TGF-β,TLR-4 and p-ERK1/2 in fibroblasts were investigated.Additionally,the area of expanded skin,thickness of the dermis,and synthesis of COL I,TGF-β,TLR-4 and p-ERK1/2 were analysed to determine the effects of S100A9 on expanded skin.Results:Increased expression of S100A9 and TLR-4 was associated with decreased extracellular matrix(ECM)in the expanded dermis.Furthermore,S100A9 facilitated the proliferation and migration of human skin fibroblasts as well as the expression of COL I and TGF-βin fibroblasts via the TLR-4/ERK1/2 pathway.We found that mechanical stretch-induced S100A9 expression and secretion of keratinocytes stimulated COL I,TGF-β,TLR-4 and p-ERK1/2 expression in skin fibroblasts.Recombined S100A9 protein aided expanded skin regeneration and rescued dermal thinning in rats in vivo as well as increasing ECM deposition during expansion.Conclusions:These findings demonstrate that mechanical stretch promoted expanded skin regeneration by upregulating S100A9 expression.Our study laid the foundation for clinically improving tissue expansion using S100A9.

食盐用量对四川腊肉加工及贮藏过程中肌肉蛋白质降解的影响

以不同食盐用量(食盐用量分别为原料肉质量的3%、4%、5%、6%、7%,用A、B、C、D、E来表示)腌制的四川腊肉为研究对象,分析了肌肉中非蛋白氮(non-protein nitrogen,NPN)、游离氨基酸(free amino acids,FAA)含量以及肌浆蛋白和肌原纤维蛋白在加工贮藏过程中随时间变化的规律。结果显示:A、B、C组NPN含量较高;C组FAA含量最高,含量最高时达到11.75 mg/g;肌浆蛋白、肌原纤维蛋白在腊肉的腌制期和烟熏期大量降解,而肌原纤维蛋白的降解主要集中在分子质量大于99 k D的区域,A、B、C组的两种蛋白变化趋势一致,D、E组一致。结果表明:食盐用量会抑制蛋白质的降解,当食盐用量为肉质量的5%时,最有利于游离氨基酸的生成,并且腊肉中较低的食盐用量会缩短贮藏阶段肌浆蛋白含量达到最大值的时间,却延缓了肌原纤维蛋白含量达到最大值的时间。

热处理下的猪肉蛋白质特性

在加热的条件下,猪肉蛋白质发生热变性和热降解。加热使猪肉中心温度分别达到40、50、60、70、80、90、98℃,且持续0、10、20min,采用SDS-PAGE电泳分析不同温度处理下猪肉的可溶性肌浆蛋白和肌原纤维蛋白的变化。结果显示,随着加热温度的升高,猪肉的可溶性肌浆蛋白随之降解,而可溶性肌原纤维蛋白的含量呈先升高后下降的趋势,其中,分子量为34kD和37kD的肌联蛋白是热稳定性蛋白,43kD的G-肌动蛋白较稳定,而肌球蛋白重链(190～200kD)在加热至60℃时开始降解。因此,可以通过不同的蛋白条带鉴定猪肉加热的最终温度。另外,采用蒸、炒、炸、烤、微波和煮的方式加热不同组织的猪肉,采用SDS-PAGE电泳分析不同加热方式处理下猪肉的可溶性肌浆蛋白和肌原纤维蛋白的变化,发现加热方式对猪肉加热升温速率影响很大,微波加热升温最快,裹粉油炸升温最慢。

加热处理对北京油鸡和黄羽肉鸡质构以及蛋白特性的影响

北京油鸡和黄羽肉鸡加热过程中的蒸煮损失、pH、剪切力变化及肌肉蛋白降解对其特殊质构和风味的形成具有重要意义。本研究以北京油鸡和黄羽肉鸡不同加热阶段为研究对象,采用常规物化特性测定方法及SDS-PAGE电泳分析北京油鸡和黄羽肉鸡肌肉质构的变化及蛋白降解情况。结果表明:随着加热温度的升高,北京油鸡和黄羽肉鸡的蒸煮损失均有明显的增加,而两者的剪切力和pH值以及蛋白质的降解呈现不同的变化。

禁食处理和宰后时间对鸡肉蛋白磷酸化水平的影响

目的:探讨宰后肌浆蛋白和肌原纤维蛋白的磷酸化水平,并研究宰前禁食和宰后时间对鸡肉蛋白磷酸化水平的影响。方法:将30只三黄鸡随机分为3组:未禁食、禁食12h和禁食24h组。宰杀后立即剥取胸大肌并将其分切成3块。1块肉样作为宰后0h样品,另外2块肉样在0℃条件下存放3h和10h,分别作为宰后3h和10h的样品。将一维电泳和Pro-Q Diamond染色结合起来分析其肌浆蛋白和肌原纤维蛋白的磷酸化水平。结果:禁食12h组的肌浆蛋白磷酸化水平最高,而肌原纤维蛋白的磷酸化水平则随着禁食时间的延长而逐渐增加(P<0.05)。此外,禁食组与未禁食组中的绝大多数蛋白均在宰后3h时达到最大值(P<0.05)。结论:肌浆蛋白和肌原纤维蛋白的磷酸化水平都会受宰前禁食和宰后时间的影响,且禁食可能通过改变肌肉中蛋白质的磷酸化程度而影响宰后肌肉僵直的进程,进而影响肌肉嫩度。

金华火腿加工过程中蛋白质降解情况的研究

以金华火腿为原料,主要从原料、腌制期、发酵初期、发酵中期、发酵末期五个阶段取样,对金华火腿在加工过程中半膜肌和股二头肌的肌浆蛋白和肌原纤维蛋白的降解情况进行了研究。结果表明,金华火腿在加工过程中,半膜肌的蛋白质降解主要是在腌制期和发酵初期;股二头肌的蛋白质降解主要是在腌制期和发酵中后期。本文同时测定主要呈味氨基酸在加工过程中含量的变化情况,发现蛋白质的降解作用与主要氨基酸的生成相关。

冰温贮藏对羊肉中蛋白质磷酸化水平的影响

【目的】通过测定冰温贮藏及冷藏过程中肌肉肌浆蛋白与肌原纤维蛋白的磷酸化水平,分析冰温贮藏对蛋白质磷酸化水平的影响,为肉类冰温贮藏品质调控提供理论依据。【方法】选取大尾寒羊与小尾寒羊杂交公羊的背最长肌于冷藏和冰温条件下成熟,分别在0.5 h、12 h、24 h、3 d、5 d、9 d取样测定蛋白激酶活性、肌浆蛋白与肌原纤维蛋白的磷酸化水平。采用蛋白激酶活性测定试剂盒、运用酶联免疫的方法检测各处理组蛋白激酶的活性随贮藏时间的变化;通过SDS-PAGE电泳、荧光染色的方法得到全蛋白染色与磷酸化染色的肌浆蛋白与肌原纤维蛋白条带,运用Quantity One软件分析各处理组各处理时间的肌浆蛋白及肌原纤维蛋白的磷酸化水平。【结果】贮藏初期(0.5—12 h),冰温组蛋白激酶活性显著升高(P<0.05),冷藏组蛋白激酶活性则显著降低(P<0.05),贮藏12 h—9 d过程中,冰温组蛋白激酶活性均显著高于冷藏组(P<0.05)。两处理组蛋白激酶活性均随贮藏时间的延长而逐渐降低,且冰温组蛋白激酶活性均显著高于冷藏组(P<0.05)。对肌浆蛋白染色效果图中分布于15—250 k Da的17个蛋白条带逐一进行分析,结果表明贮藏温度极显著影响肌浆蛋白各蛋白条带的磷酸化水平(P<0.001)。冷藏组肌浆蛋白整体磷酸化水平先升高后降低,贮藏第3天达到最大值,冰温组肌浆蛋白整体磷酸化水平先降低后升高,最小值出现在贮藏第24天,贮藏第12天至3天时,冷藏组肌浆蛋白整体磷酸化水平高于冰温组(P<0.05),贮藏第9天时,冰温组肌浆蛋白整体磷酸化水平高于冷藏组(P<0.05)。对肌原纤维蛋白染色效果图中分布于15—250 k Da的20个蛋白条带逐一进行分析,结果表明不同贮藏温度对所有肌原纤维蛋白条带的磷酸化水平均产生极显著影响作用(P<0.001)。两处理组肌原纤维蛋白整体磷酸化水平均随贮藏时间的延长呈现先升高后降低的趋势,冷藏组与冰温组最大值分别出现在24 h和12 h,贮藏初期(0.5—12 h),两处理组间肌原纤维蛋白整体磷酸化水平无显著差异(P<0.05),贮藏24 h至贮藏期结束,冷藏组肌原纤维蛋白整体磷酸化水平始终高于冰温组(P<0.05)。【结论】冰温贮藏通过影响蛋白激酶的活性来调控蛋白质的磷酸化水平,进而通过影响糖酵解途径、肌肉收缩及骨架蛋白降解来间接调控肉品质。

微波预油炸鸡胸肉块工艺条件的优化

以鸡胸肉为原料,研究微波预油炸调理鸡胸肉制品的加工工艺。分别采用低火力(160 W)、中火力(480 W)、高火力(800 W)加热鸡胸肉0、15、30、45、60、75、90 s,采用质构分析仪测试法(TPA)和聚丙烯酰胺凝胶电泳(SDSPAGE)分析复热后肌浆蛋白和肌原纤维蛋白的变化情况。结果表明,随着微波加热火力和时间的增加,肌浆蛋白变性程度越来越迅速,鸡块的肌原蛋白发生了一定程度的降解,肌原纤维蛋白的热稳定性高于肌浆蛋白,经含水量和脆性分析,推荐采用中火力(480 W)加热45 s的组合,中心温度能够达到75℃,为最优的复热条件,此时产品的弹性和粘聚性达到最大值。