Fish Myosin Fragments Solubility and ANS-Fluorescence Intensity Affected by n-Butanol

Changes in the solubility and 8-anilino-1-napthalene sulfonate (ANS)-fluorescence intensity of oval filefish, tilapia, and black marlin myo-sins and their fragments by n-butanol were examined in connection with myosin gel-forming abilities. The thermal gel-forming abilities of myosins were greatly enhanced by the addition of 0.3–0.8M n-butanol. KC1 concentration-solubility curves revealed that after n-butanol addition a marked decrease in the solubility was observed for myosins and S-1s, whereas there was a slight decrease for rods. The fluorescence intensity of myosins-ANS in the presence of n-butanol increased markedly by heating at 30° and 35°C. A similar increase in the fluorescence intensity occurred in all S-ls-ANS, but not in rods.     

基于分子对接技术研究鱼源抗冻多肽与鱼肌球蛋白的相互作用

冻藏期间蛋白质冷冻变性是引起解冻后鱼糜凝胶化能力下降的主要原因之一,而肌球蛋白重链（Myosin Heavy Chain,MHC）是鱼糜凝胶形成的主要贡献者。本研究使用不同生物酶酶解制备抗冻多肽,通过计算机模拟酶解技术筛选抗冻多肽。利用蛋白质同源建模构建海鲈鱼肌球蛋白空间结构,通过分子对接和分子动力学模拟解析抗冻多肽与海鲈鱼肌球蛋白重链的作用位点及可能的作用机制。结果表明,胰蛋白酶酶解物具有高抗冻活性,对菌体低温胁迫保护达到80.35%±4.39%,并具有良好的热滞活性及抑制重结晶作用。模拟胰蛋白酶酶解获得的肽段GPR与GPAGGK可以与肌球蛋白重链通过分子间作用力结合,其中GPAGGK的结合更为稳定。这种相互作用可以阻碍肌球蛋白在温度变化中的结构改变,其机理可能是抗冻多肽结合在肌球蛋白重链的结构空腔上,影响了结合水解离后引起的疏水键及二硫键等化学键的形成,阻碍蛋白侧链聚集、结构改变和冰晶的位移等,这有利于鱼糜及鱼糜制品在冷冻贮藏中的品质保持。本研究结果为抗冻多肽应用于鱼糜及其制品在冷冻贮藏过程中品质保持的应用提供科学依据。     

Denaturation of Tilapia Myosin Fragments by High Hydrostatic Pressure

ABSTRACT: Hydrostatic pressures (50 to 300 MPa) were applied at 0 °C for 50 min to determine the aggregation and viscoelastic properties of tilapia ( Orechromis niloticus ) myosin fragments: subfragment-1 (S-1) and rod. With pressure lower than 150-MPa treatment, S-1 underwent intermolecular interaction to increase its elastic properties. After a 200-MPa treatment, S-1 unfolded, aggregated, and decreased its solubility. A turbid solution was obtained after pressurization over 200 MPa. Further, S-1 transformed to a more elastic gel with pressure increasing. At 200 MPa, S-1 denatured entirely with no change of enthalpy detected by differential scanning calorimetry (DSC). However, all properties of rod did not change during pressurization. This study reveals that S-1 contributes the initiation of gel formation in myosin, and the role of rod is not clear. Keywords: hydrostatic pressure, S-1, rod, denaturation     

Solubilization of Fish Muscle Myosin by Sorbitol

Sugars and their reduced forms decreased the turbidity of myofibril suspension in a concentration dependent relation. The extent of turbidity decrease was compound specific; glucose sorbitol lactitol = lactose=maltitol. Turbidity decreasing effect of sugars correlated well with the number of hydroxyl groups. Sorbitol reduced the NaCl concentration required for solubilization of myofibrils. Moreover, filament formation by myosin was strongly inhibited by sorbitol.     

A Simplified Myosin Preparation from Marine Fish Species

A simple and rapid method for the purification of fish myosin with high yield was developed. The method consisted of washing chopped fish muscle with a 0.1M KCl solution, an extraction of myosin with a 0.45M KCl solution containing ATP, and steps of reprecipitation and redissolution by changes in ionic strength. Actin can easily be obtained as a component of the myosin preparation.     

鱼肌球蛋白与腥味物质的结合作用研究

为了阐明花鲢鱼肌球蛋白与特征腥味物质的结合作用,构建肌球蛋白-腥味化合物作用体系,采用顶空-气相色谱-质谱联用、分子模拟、差示扫描量热法、拉曼光谱等技术研究肌球蛋白与腥味物质间的作用.结果表明,肌球蛋白与6种腥味物质间的结合能力随碳链长度及不饱和度的增加而显著增加,且1-辛烯-3-醇的结合能力显著低于醛类化合物;腥味物...     

Protein-Protein Interaction and Fat and Water Binding in Comminuted Flesh Products

The possible role of protein-protein interaction in influencing the water and fat binding capacity of comminuted flesh products was studied. Water and fat binding by meat batters diminish when temperatures exceed 16°C during comminution. The loss of binding capacity was partially reversible, and cooling the batters to 0°C by addition of dry ice and rechopping allowed a partial recovery of the fat and water binding capacity. A cause and effect relationship between the change in fat and water binding by meat batters on chopping and protein-protein interaction in actomyosin solutions was demonstrated. Protein-protein interaction results in molecular aggregation and when measured as an increase in light scattering absorbance at 320 nm by a protein solution, the reaction was shown to be reversible between 4 and 30°C. When actomyosin solutions extracted from meat samples showed reduced protein-protein interaction in the temperature range used in chopping, the batters made from these meats also showed the least loss in fat and water binding capacity with prolonged chopping. Controlling temperatures during chopping within a range where protein-protein interaction in actomyosin solutions was found to be minimal, allowed prolonged chopping without loss in fat and water binding.     

Fish Myosin Aggregation as Affected by Freezing and Initial Physical State

ABSTRACT: Fish myosin obtained from Tilapia nilotica was solubilized in 20 mM Tris-HCl, pH 7.0, with 0.6 M KCl (solution model system), or suspended without salt (suspension model system). Changes in % soluble protein, Ca²⁺-ATPase activity, and total and reactive -SH groups during frozen storage were evaluated. Frozen induced aggregation of fish myosin showed different behavior depending upon its initial physicochemical state. When myosin was solubilized prior to frozen storage, head-to-head interactions seemed to be more involved in protein aggregation with a strong participation of disulfide bonds. On the contrary, a preferentially side-to-side mechanism might be involved in the aggregation of myosin upon suspension, with a minor interaction of -SH groups.     

纳米鱼骨对鲢鱼肌球蛋白凝胶性能的影响

本实验以鲢鱼骨为原料制成纳米鱼骨(nano-scaled fish bone,NFB)、微米鱼骨(micro-scaled fish bone,MFB),并以CaCl2为对照,将其加入至鲢鱼肌球蛋白中,通过静态流变学、动态流变学、表面疏水性分析以及活性巯基浓度和溶解度的测定,比较不同钙源对肌球蛋白凝胶性能的影响.结果表...     

2 种天然抗氧化剂与鲢鱼肌球蛋白的相互作用

研究2 种天然抗氧化剂表没食子儿茶素没食子酸酯（epigallocatechin gallate,EGCG）、白藜芦醇（resveratrol,RE）与鲢鱼肌球蛋白之间的相互作用。采用荧光光谱与圆二色谱技术分别探究EGCG、RE与鲢鱼肌球蛋白分子间相互作用的结合情况和其对肌球蛋白微观结构的影响。荧光光谱结果表明：EGCG、RE与鲢鱼肌球蛋白之间发生相互作用均会导致肌球蛋白荧光猝灭现象的发生,且荧光猝灭方式都为静态猝灭。通过热力学数据分析得出EGCG、RE与肌球蛋白分子结合的主要作用力是氢键和范德华力;并利用Stern-Volmer方程处理数据得到EGCG、RE与肌球蛋白在不同温度条件下的结合常数和结合位点数。圆二色谱及表面疏水性结果表明,EGCG、RE诱导了肌球蛋白结构的变化,EGCG使肌球蛋白α-螺旋相对含量增加,表面疏水性降低;而RE对肌球蛋白二级结构无明显作用,但会使其表面疏水性增加。     

基于图聚类的蛋白质相互作用网络功能模块探测

作者采用了基于模块性的图聚类算法来探测蛋白质相互作用网络中的集团,在具有2 617个节点11855个相互作用的酵母蛋白质相互作用网络中探测出177个集团,同时采用慕尼黑信息中心(Munich Information Center,MIPS)的层次功能注释对其进行了注释,并且验证得到的集团的确是内部连接紧密的子图。     

纳米鱼骨在肌球蛋白胶凝过程中钙赋存形态的变化及分布

以鲢鱼骨为原料制备纳米鱼骨（nano fish bone,NFB）,将其加入肌球蛋白中,通过钙赋存形态、表面元素、微观结构及低场核磁等研究肌球蛋白胶凝过程中NFB-Ca的形态变化与分布。结果表明,与空白组肌球蛋白样品相比,NFB的添加显著提高了肌球蛋白样品中Ca元素的含量（P＜0.05）,且NFB-Ca主要以不溶性钙形态存在（＞95%）。40 ℃加热显著增加了离子钙的含量,而进一步于90 ℃加热时,离子钙向其他形态转变。肌球蛋白胶凝过程中NFB释放的可溶性钙部分参与形成盐桥,转变为不溶性钙,促进肌球蛋白分子间发生交联,形成激光共聚焦可观察到的较为均一连续的凝胶网络结构。低场核磁结果显示均匀的凝胶结构有利于束缚更多的水分,降低自由水的流动性。同时,随加热的进行,添加NFB的肌球蛋白样品表面Ca元素增多,分布的均匀性也有所提高。     

Interaction of Commercial Dairy Proteins and Chicken Breast Myosin in an Emulsion System

The compatibility of commercial dairy proteins with chicken breast myosin in an emulsion system was examined. SDS-PAGE of the solution remaining after emulsion formation indicated that myosin incorporation into the cream layer was much more limited with the flexible additives such as sodium-caseinate and milk protein isolate resulting in decreased emulsion stability. However, myosin incorporation and emulsion stability were maintained with whey protein concentrate or whey protein isolate at all additive levels. No hydrophobicity changes were found in myosin with additive mixtures except for heated myosin and WPC (P=0.04). The stability of an emulsion was primarily determined by the amount of myosin incorporated.     

Protein-Protein Interactions Between Soybean Beta-conglycinin (B1-B6) and Myosin

Protein-protein interactions between soybean beta-conglycinin (B₁- B₆) and myosin were studied by turbidity, solubility and SDS-poly- acrylamide gel electrophoresis (SDS-PAGE) analysis. Turbidity and solubility studies showed that, under the experimental conditions used, these proteins interacted at temperatures between 60° and 100°C, while SDS-PAGE analysis indicated that the interaction also occurred at 50°C. The interasction was such that no detectable complexing between these two proteins was observed. The presence of beta-conglycinin resulted in diminished aggregations of myosin heavy chains between 50° and 100°C.     

Studies on the Subunits Involved in the Interaction of Soybean 11S Protein and Myosin

Protein-protein interaction between soybean 11S protein and myosin in a buffer system was studied using gel filtration chromatography and electrophoresis after incubating the single or combined proteins at temperatures between 4°C and 100°C. The elution profiles of 11S protein and myosin indicated that interaction between these two proteins occurred only at temperatures between 85° C and 100°C. The degree of interaction increased as temperature increased from 85 to 100°C. The interaction was not between native soy 11S and myosin, but between partially dissociated soy 11S (intermediary subunits, IS) or fully dissociated soy 11S (basic subunits) and myosin heavy chains. The rate of interaction was proposed as being more rapid between myosin and the basic subunits than between myosin and IS.     

鱼皮明胶和多酚组装行为与相互作用

研究不同结构多酚与鱼皮明胶(fish skin gelatin,GLA)间的相互作用及组装行为,期望对水产品加工、副产品的利用和新型食品配料的开发提供科学依据,同时为多酚-蛋白质复合物在食品领域的应用提供理论指导.选取单宁酸(tannic acid,TA)、表没食子儿茶素没食子酸酯(epigallocatechin g...     

Investigations of Soybean 11S Protein and Myosin Interaction by Solubility, Turbidity and Titration Studies

Solubility tests, turbidity tests, and titration experiments were employed to study the possible protein-protein interactions between purified soybean 11S protein and skeletal muscle myosin and the involvement of protein subunits in the interactions. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used as an analytical tool for identification of the protein species. These tests indicate that these proteins interacted at temperatures between 85°C and 100°C. Solubility and titration experiments showed that acidic subunits of soybean US protein had little or no interaction with myosin heavy chain subunits. In contrast, soybean 11S basic subunits interacted with myosin heavy chains. The SDS-PAGE method indicated that eight commercial soy protein isolates had a similar protein species composition, but certain proteins in some isolates had lost their availability for water extraction. This may account for different functional properties exhibited by differen soy protein isolates.     

溶液体系中迷迭香酸与肌球蛋白的相互作用及其对蛋白理化特性的影响

利用荧光光谱、圆二色谱、电泳等技术,研究溶液体系中肌球蛋白与迷迭香酸(rosmarinic acid,RA)的相互作用方式以及不同NaCl浓度条件下RA的添加对肌球蛋白构象和理化特性的影响。结果表明,RA对肌球蛋白的内源荧光具有较强的静态猝灭作用,且主要通过疏水相互作用结合,不存在共价交联。RA可以促进肌球蛋白结构展开,α-螺旋含量降低,更多活性基团暴露,表面疏水性增加。不同NaCl浓度条件下,添加RA会降低Zeta电位的绝对值,导致肌球蛋白的溶解度降低,浊度和粒径增大。低盐浓度下(0.2～0.4 mol/L NaCl),添加RA降低了肌球蛋白的乳化性;中高盐浓度(0.6～1.0 mol/L NaCl)下,RA对肌球蛋白的乳化性影响较小。