转谷氨酰胺酶催化大豆蛋白和乳清蛋白合成耐热性聚合蛋白

用商品级转谷氨酰胺酶 （TG- B）聚合大豆蛋白和乳清蛋白形成高耐热、耐酸的蛋白聚合物。方法 :蛋白聚合物的合成量由 SDS- PAGE电泳结合凝胶成像分析测定 ;蛋白聚合物的耐热性用差示扫描量热法 （DSC）测定 ;蛋白聚合物的酸溶解性用双缩脲法测定。结果 :TG- B聚合大豆蛋白和乳清蛋白形成的蛋白聚合物的最适条件为 :p H为 6- 7;反应温度 30～ 45℃ ,反应时间 4h,加酶量为 6当量单位 / g蛋白 ,在此条件下蛋白聚合物的转化量可达 30 % ,所合成蛋白聚合物可耐 1 30℃的热处理而不发生变性 ;并在 p H3.2～ 4.3范围不发生沉淀。      

转谷氨酰胺酶催化大豆蛋白和乳清蛋白合成耐热性聚合蛋白

用商品级转谷氨酰胺酶 (TG- B)聚合大豆蛋白和乳清蛋白形成高耐热、耐酸的蛋白聚合物。方法 :蛋白聚合物的合成量由 SDS- PAGE电泳结合凝胶成像分析测定 ;蛋白聚合物的耐热性用差示扫描量热法 (DSC)测定 ;蛋白聚合物的酸溶解性用双缩脲法测定。结果 :TG- B聚合大豆蛋白和乳清蛋白形成的蛋白聚合物的最适条件为 :p H为 6- 7;反应温度 30～ 45℃ ,反应时间 4h,加酶量为 6当量单位 / g蛋白 ,在此条件下蛋白聚合物的转化量可达 30 % ,所合成蛋白聚合物可耐 1 30℃的热处理而不发生变性 ;并在 p H3.2～ 4.3范围不发生沉淀。     

转谷氨酰胺酶催催化大豆蛋白和乳清蛋白合成耐热性聚合蛋白注

用商品级转谷氨酰胺酶（TG－B）聚合物大豆蛋白和乳清蛋白形成高耐热,耐酸的蛋白聚合物,蛋白聚合物的合成量由SDS－PAGE电泳结合 胶成像分析测定,蛋白聚合物的耐热性用差示扫描量热法（DSC）测定,蛋白聚合物的酸溶解性用双缩脲法测定,结果表明TG－B聚合大豆蛋白和乳清蛋白形成的蛋白聚合物的最适条件为：pH为6－7,反应温度30℃－45℃,反应时间4h,加酶量为6当量单位／g蛋白,在此条件下蛋白聚合的转化量可达305,所合成蛋白聚合物可耐130℃的热处理而不发生变性,并在pH3.2-4.3范围不发生沉淀。     

微生物转谷氨酰胺酶催化乳清蛋白聚合研究

采用SDS－PAGE分析，研究了不同条件下微生物转谷氨酰胺酶（MTGase）催化乳清蛋白（WPI）聚合。结果显示，MTGase可催化乳清蛋白的β－乳球蛋白（β-LG）和α－乳清蛋白（α－LA）聚合，形成低聚物或生物聚合物，其中β-LG更易受MTGase的催化，当TGase酶浓度一定时（0.5U/mL),TGase催化WPI聚合的最佳底物质量分数范围为2％－4％，对WPI进行加热预处理，同时添加还原剂，可明显提高MTGase对WPI的催化活性，MTGase催化WIP的最适PH值范围为6．5－7．5，当WPI经预热处理（85℃，15min），同时添加20mmol/L的DTT，TGase催化WPI聚合12h，可使质量分数为92％的β-LG和质量分数为75％的α－LA聚合。     

大豆蛋白、酪蛋白、卵清蛋白、浓缩乳清蛋白及转谷氨酰胺酶对鸡肉肠出品率和硬度的影响

本文采用两因素析因实验设计,研究了转谷氨酰胺酶和四种非肉蛋白(大豆蛋白、酪蛋白、卵清蛋白、浓缩乳清蛋白)对鸡肉肠出品率和硬度的影响。结果显示,随着浓度的增加,四种非肉蛋白均可显著增加鸡肉肠的出品率(p<0.01);转谷氨酰胺酶对出品率没有影响,与非肉蛋白之间亦无交互作用。转谷氨酰胺酶在提高鸡肉肠硬度的同时和非肉蛋白间有交互作用,其中酪蛋白和大豆蛋白能提高硬度,而卵清蛋白和浓缩乳清蛋白则显著降低了鸡肉肠的硬度(p<0.05)。     

转谷氨酰胺酶的特性及其聚合大豆蛋白的研究

转谷氨酰胺酶作为一种生物催化剂,可以催化蛋白质赖氨酸上ε-氨基和谷氨酰胺上γ-羟酰胺基之间的交联反应,在蛋白质分子间或分子内形成ε-(γ-谷氨酰胺基)赖氨酸(G-L)键。此催化过程具有反应条件温和、底物选择性好的特点,交联聚合后蛋白的功能特性,如凝胶性、热稳定性和保水性等会得到明显改善,因此,其广泛应用于动植物蛋白的改性中。本文介绍了不同来源转谷氨酰胺酶的特性和其在不同食品体系中的作用,并对转谷氨酰胺酶催化大豆蛋白聚合的研究进行了综述。     

转谷氨酰胺酶对大豆蛋白粘度的影响

利用转谷氨酰胺酶(TGase)对大豆蛋白进行改性,并对其粘度进行研究。随着TGase加量的增加,蛋白溶液的粘度不断增加。脱脂豆粉(LTSP)、大豆分离蛋白(SPI)和11S蛋白的粘度均在45℃时最大,而大豆7S蛋白在温度为50℃时粘度最大。随反应时间的延长,体系粘度呈先增加后减少的趋势,大豆11S蛋白的粘度在反应时间为90min时达到最大,其他三种蛋白在120min时粘度最大。      

转谷氨酰胺酶对大豆蛋白粘度的影响

利用转谷氨酰胺酶(TGase)对大豆蛋白进行改性,并对其粘度进行研究。随着TGase加量的增加,蛋白溶液的粘度不断增加。脱脂豆粉(LTSP)、大豆分离蛋白(SPI)和11S蛋白的粘度均在45℃时最大,而大豆7S蛋白在温度为50℃时粘度最大。随反应时间的延长,体系粘度呈先增加后减少的趋势,大豆11S蛋白的粘度在反应时间为90min时达到最大,其他三种蛋白在120min时粘度最大。     

乳清蛋白在转谷氨酰胺酶作用下包埋益生菌的研究

为了提高双歧杆菌在人体胃肠道中的存活率,以乳清蛋白为壁材,转谷氨酰胺酶为交联剂,通过乳化凝胶的方法制备包埋有两歧双歧杆菌的蛋白质微球。实验表明:以此工艺制备的微球成球性较好,粒径为(308.2±16.2)μm,益生菌包埋率为87.8%±10.0%,与未包埋的两歧双歧杆菌比较,经过包埋后的两歧双歧杆菌在模拟胃液和高胆盐溶液中的存活率分别提高了5个和2个对数值。      

乳清蛋白在转谷氨酰胺酶作用下包埋益生菌的研究

为了提高双歧杆菌在人体胃肠道中的存活率,以乳清蛋白为壁材,转谷氨酰胺酶为交联剂,通过乳化凝胶的方法制备包埋有两歧双歧杆菌的蛋白质微球。实验表明:以此工艺制备的微球成球性较好,粒径为(308.2±16.2)μm,益生菌包埋率为87.8%±10.0%,与未包埋的两歧双歧杆菌比较,经过包埋后的两歧双歧杆菌在模拟胃液和高胆盐溶液中的存活率分别提高了5个和2个对数值。     

Biopolymers Produced by Cross-linking Soybean 11S Globulin with Whey Proteins using Transglutaminase

Heterogeneity of biopolymers was determined by cross-linking acetylated-11S acidic subunits (Ac-11S) of soy protein with α-lactalbumin and β-lactoglobulin. The extent of polymerization was determined by electrophoresis and HPLC. Differential scanning calorimetry (DSC) was used to determine thermal properties of starting proteins and biopolymers. HPLC data demonstrated the absence of biopolymers from Ac-11S, acetylated α-lactalbumin and acetylated β-lactoglobulin when each was incubated separately with transglutaminase (TG). However, Ac-11S formed biopolymers with α-lactalbumin and β-lactoglobulin when TG was added. TG catalyzed the formation of heterologous and homologous biopolymers from whey protein isolate (WPI) and soybean 11S globulin (11S). Cross-linking WPI and 11S provided biopolymers with improved heat stability which may be useful to provide functionality to food products.     

Properties of Biopolymers from Cross-linking Whey Protein Isolate and Soybean 11S Globulin

Biopolymers were prepared by cross-linking whey protein isolate (WPI) and soybean 11S using transglutaminase. Electrophoretic pattern, solubility, emulsification, hydrophobicity and foaming properties of the biopolymers were determined. SDS-PAGE showed bands corresponding to high-molecular-weight components (MW>200 kDa). Biopolymer solubility was > 90% at pH 3 and below, and at pH 7 and above. Emulsifying properties of biopolymers were lower than those of WPI. The foaming capacity of the biopolymers (23.6 mL) and WPI/11S mixture (22.7 mL) were similar to that of egg albumin (20.3 mL). The foaming stability of the biopolymers (122 min) was higher than that of WPI/11S mixture (33.7 min), and was similar to that of egg albumin (132 min).     

Transglutaminase Catalysis of Modified Whey Protein Dispersions

ABSTRACT: Transglutaminase (TGase) cross-linking reactions were accomplished using a heat-modified whey protein concentrate (mWPC) substrate after pH adjustment to 8. Based on earlier reports, the degree of lactosylation with respect to β-lactoglobulin was lower in mWPC dispersions than measured in commercial whey concentrate (cWPC) protein solutions. In this study, a higher concentration of free sulfhydryl groups was detected in soluble supernatant fractions. Both factors potentially impact the availability of reactive lysine/glutaminyl residues required for TGase reactivity. The addition of 10 mM dithiothreitol (DTT) to the substrate mix, CBZ-glutaminyl glycine and hydroxylamine, revealed a 3.6-fold increase in TGase activity, likely due in part to maintenance of the catalytic cysteine residue in a reduced state. Furthermore, inclusion of DTT to mWPC dispersions significantly raised the apparent viscosity, independently of enzyme modification, while the rate of polymerization increased 2-fold based on OPA assay measurements. Limited cross-linking slightly increased the apparent viscosity, whereas extensive coupling lowered these values compared to equivalent nonenzyme-treated mWPC samples. Carbohydrate-staining revealed formation of glyco-polymers due to covalent linkages between glucosamine and mWPC proteins after TGase processing. Again, the apparent viscosity decreased after extensive enzymatic modification. Larger particles, sized 11.28 μm, were observed in the structural matrix of TGase-mWPC-fixed samples compared to 8 μm particles in control mWPC samples as viewed in scanning electron micrographs. Ultimately, the functional characteristics of TGase-mWPC ingredients may be custom-designed to deliver alternative functional attributes by adjusting the experimental reaction conditions under which catalysis is achieved. Practical Application: Taken together, these results suggest that unique TGase-mWPC and/or TGase-mWPC-glucosamine ingredients may be designed to provide novel, value-added, polymeric/glyco-polymeric protein products that afford added benefit for the milk industry.     

Properties of Films Produced by Cross-linking Whey Proteins and 11S Globulin Using Transglutaminase

Transglutaminase (TG) was used to produce films from whey protein isolate, soybean 11S globulin and a mixture of the two (1:1, wt/wt). Solubility of TG cross-linked films was lower than that of control films at pH 3, 4, 6 and 8. Solubility of control films in 6.6M urea and in 10% SDS was higher than that of TG cross-linked films. Hydrolysis of control and TG cross-linked films by trypsin and α-chymotrypsin was similar after 24h incubation. Mean thickness of films ranged from 69 to 77 μm and there were no differences among thicknesses. Average tensile strength values of TG cross-linked films were two times greater than those of the homologous controls.     

利用微生物转谷氨酰胺酶回收大豆乳清废水

以大豆乳清废水为研究对象,以蛋白质含量为指标,通过单因素试验和正交实验研究了以微生物转谷氨酰胺酶(MTGase)对大豆乳清蛋白的聚合作用的条件,并对处理前后的大豆乳清废水中的蛋白质进行了分析.结果表明,微生物转谷氨酰胺酶对大豆乳清废水作用的最佳条件为:添加酶活为1 U/mL的酶6mL、反应时间1h、反应温度35℃pH ...     

Transglutaminase Cross-linking of Whey/Myofibrillar Proteins and the Effect on Protein Gelation

ABSTRACT: Transglutaminse (TGase)-catalyzed interactions of whey (WPI)/myofibrillar (MPI) protein isolates were investigated under 5 conditions: (1) ionic strengths; (2) calcium/ethylenediaminetetra-acetic acid (EDTA); (3) enzyme:substrate ratio; (4) WPI:MPI ratio; and (5) preheating of WPI (80 °C). TGase treatments of MPI in distilled water converted myosin heavy chain and actin into lower-molecular-weight polypeptides. The reaction, accelerated by the presence of WPI but diminished by NaCl, was completely reversed upon extended incubation. There was no visible WPI/MPI cross-linking; and the enzyme:substrate or WPI:MPI ratio, preheating, calcium, and EDTA did not influence the enzyme reaction. TGase treatment did not alter the melting pattern of WPI/MPI mixtures, but markedly enhanced their thermal gelling ability.     

聚丙烯微孔膜固定化转谷氨酰胺酶在大豆乳清废水处理中的应用

将固定化转谷氨酰胺酶酶膜应用到酶膜反应器中,对大豆乳清废水进行催化使其发生聚合并被截留,从而减轻大豆乳清废水对环境的污染,并确定其最佳影响条件,得出在最佳条件下进行处理的蛋白截留率为78.4%。对处理前后大豆乳清废水进行分析,其主要成分指标发生了很大变化,如蛋白质含量、生化需氧量(biochemical oxygen demand,BOD)值、化学需氧量(chemical oxygen demand,COD)值、灰分含量等指标较处理前发生显著下降。     

谷氨酰胺转氨酶对大豆与小麦混合蛋白凝胶性质的影响

研究谷氨酰胺转氨酶（transglutaminase,TG）对大豆和小麦混合蛋白凝胶特性的影响,通过游离巯基含量、表面疏水性、热特性、二级结构和微观结构等测定对混合蛋白凝胶的构象进行了表征。结果显示,当大豆蛋白比例低于45%时,随着大豆蛋白所占比例的增加,凝胶强度显著增强。TG交联混合蛋白凝胶后,其游离巯基减少,热稳定性增强,表面疏水性降低。与TG催化小麦蛋白相比,大豆蛋白添加量为45%的混合蛋白凝胶强度提高了62.74%,β-折叠含量增加了5.701%,游离巯基含量减少了47.48%。     

转谷氨酰胺酶对大豆分离蛋白乳状液冻融稳定性的影响

采用转谷氨酰胺酶（transglutaminase,TGase）改性提高大豆分离蛋白（soybean protein isolate,SPI）乳状液冻融稳定性。以出油率和分层系数为稳定性指标,研究TGase交联时间、添加量、冻融循环次数对SPI乳状液冻融稳定性的影响。通过显微结构、热特性分析比较研究由SPI、TGase改性SPI作为乳化剂乳状液的冻融稳定性,利用十二烷基硫酸钠-聚丙烯酰氨凝胶电泳分析酶改性对SPI组成的影响,进而分析与乳状液稳定性的关系。结果表明：经过3 次冻融循环后改性SPI制备的乳化剂仍保持较好的冻融稳定性,TGase交联时间3 h、添加量1.5%时稳定性较好,微观结构可看出改性SPI乳状液处于相对稳定状态。乳状液冻融过程中热特性的差异,反映出改性蛋白在冻融过程中乳状液结晶及融化的热行为得到了改变。十二烷基硫酸钠-聚丙烯酰氨凝胶电泳结果表明酶改性使蛋白组成发生改变,从而影响大豆蛋白的冻融稳定性。TGase改性大豆蛋白具有较好的冻融稳定性,为其在冷冻食品中应用提供理论依据。