鹰嘴豆蛋白酶解动力学研究

从酶解反应机理出发,应用数学推导的方法,以鹰嘴豆蛋白为原料,考察底物浓度、酶浓度对鹰嘴豆蛋白水解度（DH）的影 响,将水解试验结果用推导的动力学模型方程进行拟合,建立酶解动力学模型。 结果表明：鹰嘴豆蛋白水解度随着初始底物浓度（S0） 的上升而下降,随着初始蛋白酶浓度（E0）的增加而上升,碱性蛋白酶水解鹰嘴豆蛋白的速率动力学模型：R=(39.522E0-0.080 4S0)exp [-0.148(DH)],水解度-水解时间的动力学模型：DH=6.76ln[1+(5.85E0/S0-0.011 9)t],酶解反应速率常数k2为39.522 min-1,酶失活常数为 6.371 min-1,该动力学模型对试验结果有很好的拟合度,对实际酶解过程具有一定的指导作用。     

碱性蛋白酶酶解青稞蛋白质的动力学研究

为深入了解与调控碱性蛋白酶水解青稞蛋白过程,准确控制其水解程度,获得定向肽组成的酶解产物。采用碱性蛋白酶在温度55℃、pH10.0条件下酶解青稞蛋白,分析酶浓度、底物浓度对青稞蛋白水解度的影响,并建立可控酶解动力学方程。结果表明:青稞蛋白水解度随着初始底物浓度S_0的上升而下降,随着初始蛋白酶浓度E_0的增加而上升,水解速率随着水解时间的延长而下降。模型的验证结果显示,预测值与实测值基本吻合,通过对E_0/S_0、反应时间的调节可有效控制水解程度,为利用酶解制备青稞活性肽的产业化实践提供指导。     

酶法水解紫菜蛋白动力学研究

为阐明酶法水解紫菜蛋白的动力学特性,研究了酶解时间、初始pH值、温度、酶浓度、底物浓度对紫菜蛋白水解度的影响,建立紫菜蛋白水解动力学方程.结果表明:酶解温度50℃、初始pH 9.0为最适水解条件.紫菜蛋白的水解度随着酶浓度的升高而增强,随底物浓度的增加而减弱.在此条件下,碱性蛋白酶水解紫菜蛋白的动力学方程:X=3.597ln[1+(82.788E0/S0-3.058)t],总水解速率方程:am=297.8×(E0-11S0/297.8)×exp(-0.278x),为合理确定酶解反应实验的各种参数提供理论依据.     

白果蛋白可控酶解动力学模型研究

对白果蛋白的酶解动力学机制进行研究,建立碱性蛋白酶酶解白果蛋白的动力学模型。最终建立水解动力学模型为:水解速率R=(16.119E0-0.1221S0)·exp[-0.3345(DH)],水解度DH=2.989ln[1+(0.4675E0/S0-0.0861)t],并求得该体系反应速率常数k_2=16.119 min~(-1),酶失活常数Kd=0.467 5 min~(-1),达到控制酶解过程的目的。验证试验表明,模型得到水解度的理论值与实际值基本吻合,该动力学模型具有一定的实用价值。     

酶法制取大豆油脂过程中的蛋白酶解动力学

通过数学方法推导和对Alcalase碱性蛋白酶酶解大豆中蛋白实验的系统研究,得到Alcalase碱性蛋白酶酶解大豆中蛋白的动力学模型为：R＝（18.294 0E0＋0.273 4ρ0）exp（－0.256 2DH）,式中：E0为初始蛋白酶质量浓度,ρ0为初始底物质量浓度,DH为水解度。通过数学推导和对大豆蛋白酶解反应过程中Alcalase碱性蛋白酶失活的系统研究,得到膨化大豆蛋白的酶解反应过程中Alcalase碱性蛋白酶失活的动力学常数K＝4.920 4 min－1。通过拟合实验证明,建立的动力学模型与实验结果具有较好的拟合效果,证明所建立的动力学模型具有较高的实际应用价值。     

风味酶酶解小麦面筋蛋白动力学研究

研究Flavourzyme风味蛋白酶水解小麦面筋蛋白的酶解效率和反应动力学特性,调控和优化面筋蛋白的酶解工艺。研究结果表明,在该酶的最适作用条件(pH 6.0,55℃)下,10%底物,1%加酶量(酶与底物比),酶解12 h,可获得较高水解度(DH30%)和蛋白回收率(30%)。通过数学推导结合试验研究,建立了该水解反应的动力学模型。水解度(DH)和水解时间(t)的关系:DH=12.35ln[1+(2.923E0/S0-0.015)t],酶失活常数Kd约3 min-1。与试验结果相比,模型计算值与试验值吻合较好,说明该模型具有很好的实际应用价值。     

碱性蛋白酶水解米糠蛋白动力学特性研究

研究蛋白酶水解制备生物活性多肽反应机制与动力学行为,基于经典的米氏方程理论,应用数学推导结合试验研究的方法,以米糠蛋白为原料,对米糠蛋白-碱性蛋白酶体系进行酶解动力学研究.考虑蛋白质单底物水解、蛋白酶失活的机理模型,构建动力学模型R=aexp[-b(DH)],其中对参数a值和b值进行确定.利用Origin 8.0软件,对推导出的公式进行拟合得到水解速率动力学模型为R=(94.754e0-0.0597s0)exp[-0.157(DH)],水解度-水解时间的动力学模型:DH =6.37ln[1+(14.88e0/s0-0.009)t].对于米糠蛋白-碱性蛋白酶模型体系,经试验拟合,并求得该体系动力学常数:酶失活常数K4为16.144 min-1,酶解反应速率常数k2为94.754 min-1.     

复合酶水解牡蛎蛋白的动力学研究

对太平洋牡蛎蛋白进行复合酶(风味蛋白酶、胰蛋白酶的酶活力比为2.3:1)水解特性研究,探讨了底物浓度和酶浓度对水解度(DH)的影响。建立了复合酶水解牡蛎蛋白的动力学模型,确定了模型常数,并分析了多肽的平均链长、相对分子质量与酶解时间的关系。验证实验证实模型预测结果与实际测得的结果一致,表明该动力学模型具有一定的实用价值。     

鳕鱼皮胶原蛋白胰蛋白酶控制水解动力学模型

研究蛋白酶酶促水解制备生物活性肽的反应机理与动力学行为,并在假设胰蛋白酶恒温控制水解动力学遵循内切酶限制水解动力学历程的前提下,通过实验方法求出了胰蛋白酶恒温控制水解动力学模型.结果表明.胰蛋白酶对鳕鱼皮胶原蛋白进行控制水解的动力学模型为:反应速率(R)=(14.231E0-1.745S0)exp[-0.514(DH)],水解度(DH)=1.946ln[1 (7.315E0/S0-0.897)t],并求得该体系反应速率常数 K2=14.231 min-1,酶失活常数 Kd=18.809 min-1.验证实验证明,根据胰蛋白酶恒温控制水解动力学模型得到的理论水解度与实际水解度基本吻合,所建模型可用于胶原蛋白酶解反应过程的模拟和酶解反应条件的优化设计.     

鳕鱼皮胶原蛋白碱性蛋白酶Properase E控制水解动力学模型

在假设碱性蛋白酶Properase E恒温控制水解动力学遵循内切酶限制水解动力学历程的前提下,通过实验方法求出了碱性蛋白酶Properase E恒温控制水解动力学模型.结果表明,碱性蛋白酶Properase E对鳕鱼皮胶原蛋白进行控制水解的动力学模型为:反应速率(R)=(18.19E0-0.4341S0)exp[-0.714(DH)],水解度(DH)=1.401ln[1 (12.988E0/S0-0.31)t],并求得该体系反应速率常数K2=18.19min-1,酶失活常数Kd= 12.518min-1.验证实验证明,根据碱性蛋白酶Properase E恒温控制水解动力学模型得到的理论水解度与实际水解度基本吻合,所建模型可用于胶原蛋白酶解反应过程的模拟和酶解反应条件的优化设计.     

碱性蛋白酶酶解罗非鱼下脚料蛋白动力学研究

以加工罗非鱼片废弃的下脚料蛋白和碱性蛋白酶为原料,以水解度为指标,考察温度、底物质量浓度、酶用量及pH等因素对碱性蛋白酶酶解罗非鱼下脚料蛋白水解度的影响。得到碱性蛋白酶水解罗非鱼下脚料蛋白的适宜工艺条件为：酶解温度50℃、底物质量浓度20g/L、酶用量为0.067g/L、pH9.50、反应时间180min,此时水解度为22.00%。同时得到50℃条件下酶失活常数Kd为37.9min-1,反应速率常数K2为244.2min-1、米氏常数KM为29.27g/L、最大反应速度Vmax为28.41g/(min·L);并建立了相应的水解动力学模型。验证实验表明：建立的水解动力学模型与实际水解过程基本吻合。     

Formation of oligosaccharides from whey UF-permeate by enzymatic hydrolysis — analysis of factors

Two-level fractional factorial experiments were designed to study effects of enzyme (0.05 and 0.1%) and initial lactose concentrations (L_o: 14 and 23%), pH (5.0 and 7.0) and temperature (35 and 45 °C) on enzymatic formation of oligosaccharides (OS) from whey UF-permeate in a batch reactor. β-d-galactosidase from Aspergillus oryzae (A), Kluyveromyces lactis (B) and K. fragilis (C) were compared. Hydrolysis with B and C gave comparable yields which were higher than that from A at identical conditions. L_o did not influence reaction time, but concentration of OS significantly increased by increasing L_o for all enzymes. Increasing L_o reduced the yield after hydrolysis with A and B, but improved the yield for C. L_o had negligible effect on degree of hydrolysis (DH) for A and C. However, increasing L_o significantly lowered DH for B. Increasing enzyme concentration significantly reduced reaction time for A, but it had no effect on that for B and C. DH significantly decreased after increasing concentration of A. Consequently, OS and yield were reduced. Applying B and C at higher concentration improved DH, OS and yield. Increasing temperature or pH reduced DH, OS and yield for A, but increased the responses for B and C.     

Physicochemical and antioxidant properties of buckwheat (Fagopyrum esculentum Moench) protein hydrolysates

The enzymatic hydrolysis of common buckwheat (Fagopyrum esculentum Moench) protein isolate (BPI) by Alcalase and some physiochemical and antioxidant properties of the resulting hydrolysates were characterised. The hydrolysis resulted in remarkable decrease in the globulins or protein aggregates and concomitant increase in peptide fragments. The surface hydrophobicity of the hydrolysates decreased with increasing degree of hydrolysis (DH) and reached a minimum at DH 15%, but increased at further hydrolysis, whereas their amino acid compositions were unchanged. The polyphenol content of the hydrolysates gradually decreased with DH increasing from 0% to 15%, while it on the contrary increased upon further hydrolysis. The hydrolysates exhibited excellent antioxidant activities, including DPPH radical scavenging ability, reducing power and ability to inhibit linoleic acid peroxidation. The antioxidant activities of these hydrolysates were closely related to their polyphenol contents. The results indicated that polyphenol-rich buckwheat proteins are unique protein materials for the production of the hydrolysates with good nutritional and antioxidant properties.     

The effect of high solid concentrations on enzymatic hydrolysis of soya bean protein isolate and antioxidant activity of the resulting hydrolysates

This study investigated the effect of high solid concentrations on the enzymatic hydrolysis and antioxidant activities of soya bean protein isolate hydrolysates (SPIHs). The soya bean protein isolate at the concentration of 8%, 16%, 24% and 32% was hydrolysed to obtain SPIH with 21.5% degree of hydrolysis (DH), respectively. Results showed that, for the same DH, significant increases in reaction time and decrease in protein recovery were observed as solid concentrations increased. There was no significant difference in molecular weight distribution, but different amino acid compositions in supernatants of SPIH hydrolysed at different solid concentrations. The level of antioxidant amino acids in high solid concentration (32%) was higher than that in low solid concentration group, and antioxidant activity of SPIH increased with the solid concentration increased. Thus, increasing solid concentrations could increase the antioxidant activities and functional properties with low water costs.     

Effects of partial hydrolysis and plasticizer content on the properties of film from cuttlefish (Sepia pharaonis) skin gelatin

Properties of film from cuttlefish (Sepia pharaonis) ventral skin gelatin with different degree of hydrolysis (DH: 0.40, 0.80 and 1.20%) added with glycerol as plasticizer at various levels (10, 15 and 20%, based on protein) were investigated. Films prepared from gelatin with all DH had the lower tensile strength (TS) and elongation at break (EAB) but higher water vapor permeability (WVP), compared with the control film (without hydrolysis) (p < 0.05). At the same glycerol content, both TS and EAB decreased, while WVP increased (p < 0.05) with increasing %DH. At the same DH, TS generally decreased as glycerol content increased (p < 0.05), however glycerol content had no effect on EAB when gelatins with 0.80 and 1.20% DH were used (p > 0.05). DH and glycerol content had no marked impact on color and the difference in color (ΔE^∗) of resulting films. Electrophoretic study revealed that degradation of gelatin and their corresponding films was more pronounced with increased %DH, resulting in the lower mechanical properties of films. Based on FTIR spectra, with the increasing %DH as well as glycerol content, higher amplitudes for amide-A and amide-B peaks were observed, compared with film from gelatin without hydrolysis (control film) due to the increased –NH₂ group caused by hydrolysis and the lower interaction of –NH₂ group in the presence of higher glycerol. Thermo-gravimetric analysis indicated that film prepared from gelatin with 1.20% DH exhibited the higher heat susceptibility and weight loss in the temperature range of 50–600 °C, compared with control film. Thus, both chain length of gelatin and glycerol content directly affected the properties of cuttlefish skin gelatin films.     

Antioxidative and functional properties of protein hydrolysate from defatted skipjack (Katsuwonous pelamis) roe

Antioxidative and functional properties of protein hydrolysate from defatted skipjack (Katsuwonous pelamis) roe, hydrolysed by Alcalase 2.4 L (RPH) with different degrees of hydrolysis (DH) at various concentrations were examined. As DH increased, the reduction of DPPH, ABTS radicals scavenging activities and reducing power were noticeable (p < 0.05). The increases in metal chelating activity and superoxide scavenging activity were attained with increasing DH (p < 0.05). However, chelating activity gradually decreased at DH above 30%. All activities except superoxide anion radical scavenging activity increased as the concentration of hydrolysate increased (p < 0.05). Hydrolysis using Alcalase could increase protein solubility to above 80% over a wide pH range (2–10). The highest emulsion ability index (EAI) and foam stability (FS) of hydrolysates were observed at low DH (5%) (p < 0.05). Concentrations of hydrolysates determined interfacial properties differently, depending on DH. The molecular weight distribution of RPH with 5%DH (RPH5) was determined using Sephadex G-75 column. Two major peaks with the molecular weight of 57.8 and 5.5 kDa were obtained. Fraction with MW of 5.5 had the strongest metal chelating activity and ABTS radical scavenging activity. The results reveal that protein hydrolysates from defatted skipjack roe could be used as food additives possessing both antioxidant activity and functional properties.     

不同水解度猪骨蛋白水解物对水包油型乳状液乳化特性的影响

摘 要：研究不同水解度的猪骨蛋白水解物（porcine bone protein hydrolysates,PBPH）对水包油乳状液的乳化特性的影响。采用碱性蛋白酶对猪骨蛋白进行水解0、1、2、3、4、5?h得到水解度分别为0%、5.6%、7.8%、11.1%、14.3%、17.2%的样品,分别测定PBPH的乳化活性、乳化稳定性、Zeta电位、乳状液微观结构的变化以及活性肽的分子质量分布。PBPH乳化性研究表明,随着水解度的增加,乳状液的乳化活性和乳化稳定性呈现先增加后降低的趋势（P＜0.05）,水解度为11.1%时的PBPH所形成的乳状液稳定性最高,这可能与其具有最高的表面疏水性、最高的Zeta电位、最小的体积平均粒径和最均匀的液滴分布有关。分子排阻色谱测定结果表明,随着水解度的增加,酶解产物的分子质量分布表现出大分子肽含量逐渐减少,小分子肽含量逐渐增多,水解过程中伴有多肽链的断裂和蛋白质的聚集,结构变化影响不同水解度的PBPH功能性质的变化,这进一步解释了乳化性变化的原因。由此可以得出,PBPH在水解时间为3?h?（水解度为11.1%）的适度水解的条件下,其乳化性最好,可以用于制备高物理稳定性的乳状液。