酶解法制备大豆多肽的工艺研究

本实验以三种大豆制品豆饼、豆粉、豆皮为原料,选用Protease M"Amano"G酶作催化剂,探讨了分散浓度、分散时间、分散温度、水解温度、水解时间、水解pH值、酶用量等因素对酶解大豆多肽水解度(DH)、苦味和风味的影响.优选出了反应的最佳条件,并对三种原料酶解的最佳条件进行了比较,结果表明在水解度较大的情况下,大豆多肽有较好的风味并且无苦味.同时测定了大豆多肽的分子量分布和红外光谱.     

源于地龙蛋白的抗氧化肽鉴定与构效关系

为探究外源蛋白酶预酶解处理对地龙蛋白胃肠消化程度和胃肠消化后抗氧化活性的影响。该研究利用五种蛋白酶制备了不同的地龙蛋白酶解物,然后通过体外胃肠模拟消化探究这些酶解物的水解度、分子量分布和体外抗氧化活性的变化。五种蛋白酶酶解物中,碱性蛋白酶酶解物的水解度最高,为40.8%,其对DPPH、ABTS自由基的清除能力分别为27.36、175.46 μmol TE/g,ORAC值为0.70 μmol TE/mg。碱性蛋白酶酶解物经胃肠消化后的水解度、DPPH自由基清除率、ORAC值相比于地龙蛋白直接胃肠消化所得产物（EWP）分别提高了94.06%、72.21%及120.00%。GHEWP中鉴定出10 823条分子量<3 ku的肽,通过bioware.ucd.ie进行活性阈值评分筛选出活性评分最高的11个肽进行合成,验证活性,其中ATSGFFVY、HCFVLY、HLASGWY、HRYSDF、HYANMY的综合抗氧化能力较好,量子化学计算结果表明：ATSGFFVY、HCFVLY、HRYSDF、HYANMY的活性位点可能分别位于Tyr-8、Tyr-6、Tyr-3、Tyr-2上;HLASGWY的活性位点可能位于Trp-6上。该研究表明碱性蛋白酶预酶解可提高地龙蛋白的消化程度,增强其胃肠消化产物的抗氧化活性。     

猪血多肽亚铁螯合盐的体外抗氧化作用研究

研究了猪血多肽亚铁螯合盐对超氧阴离子自由基（O2-·）和过氧化氢（H2O2）的清除作用,并比较了维生素C、猪血多肽亚铁和猪血多肽对二者的清除能力。实验结果表明：猪血多肽亚铁螯合盐能清除超氧阴离子自由基（O2-·）和过氧化氢（H2O2）,维生素C、猪血多肽亚铁和猪血多肽这三种物质对超氧阴离子自由基（O2-·）和过氧化氢（H2O2）清除能力的强弱顺序为维生素C〉猪血多肽亚铁〉猪血多肽,故猪血多肽亚铁螯合盐具有较强的清除超氧阴离子自由基（O2-·）和过氧化氢（H2O2）的能力。     

酶解胶原蛋白研究进展

阐述了近年来国内外关于酶法水解胶原蛋白所做的研究工作,并对胶原多肽的应用前景进行了分析。     

Modelling the polypeptide backbone with 'spare parts' from known protein structures

An automatic procedure for building a protein polyalanine backbonefrom C positions and ‘spare parts’ retrieved froma data base of 66 high-resolution protein structures is described.Protein backbones are constructed from over-lapping fragmentsof variable length, which allows the backbone of regular secondarystructure elements to be built in one block. The procedure isshown to yield backbones which compare very favourably withthose from highly refined X-ray structures (r.m.s. deviationbetween generated and crystal structures <lÅ). Themethod is furthermore quite insensitive to experimental errorsin C positions as well as to the size of the data base, andis seen to yield valuable insight into the relationships betweensequence and 3-D structure: one example on triose phosphateisomerase, a ß-barrel protein, shows that ßloops can be considered as structurally more uncommon than ßloops. The ‘spare parts’ approach is also foundto be useful for general-purpose modelling of local structuralchanges produced by insertion or deletion of residues. It should,however, be used with caution. Crude selection criteria basedsolely on fragment length and geometric fit to the loop baseregions yield realistic backbones in about two-thirds of thetest cases (r.m.s. deviations from refined crystal structure{small tilde}lÅ). In the remaining cases, sequence information,in particular the presence of glycine residues which tend toadopt more unusual backbone conformations, must be consideredto obtain comparable results.     

Synthesis and characterization of novel triblock copolymers comprising poly(tetrahydrofuran) as a central block and poly(γ-benzyl L-glutamate)s as outer blocks

Background Bioactive and biodegradable polyurethanes (BDPUs) have drawn much attention in recent years. As part of the research program to search for novel prepolymers for BDPUs, a study was carried out on the synthesis and characterization of triblock copolymers comprising poly(tetrahydrofuran) as a central block and poly(γ-benzyl L-glutamate)s as outer blocks. Results A new macroinitiator terminated with phenylalanine was first prepared from the condensation of a distal hydroxy poly(tetrahydrofuran) with N-tert-butoxycarbonyl L-phenylalanine in the presence of dicyclohexylcarbodiimide, followed by removing the protecting group. Then, it was employed to initiate the ring-opening polymerization of γ-benzyl L-glutamate N-carboxyanhydride in varying feeding ratios to give rise to the targeted triblock copolymers. Conclusions The length of the outer poly(γ-benzyl L-glutamate) blocks was well tailored by varying the monomers to macroinitiator feeding ratio. All the triblock copolymers exhibited a nearly symmetrical and unimodal molecular weight distribution while only one distinct glass transition temperature was evidenced from −10°C to 25°C.     

双酶法提取甜瓜籽多肽的工艺研究

以甜瓜籽为原料,水解度为考察指标,采用胰蛋白酶和碱性蛋白酶双酶协同酶解法制备甜瓜籽多肽。通过单因素试验和响应面设计试验对酶解条件进行优化,结果表明:酶解的最佳工艺条件为底物浓度为3%、加酶量为4%、酶解时间为180 min、酶解温度为50℃、pH值为8、双酶质量比为6∶4,水解度达到最大值13.85%。     

汉麻籽多肽的氨基酸营养组成与体外结合胆酸盐能力的研究

以超临界CO_2脱脂制备出的汉麻籽粕为原料,经中性蛋白酶和木瓜蛋白酶复合酶水解汉麻籽粕水溶液后,采用切向流超滤系统对水解液进行分离纯化,得到组分a、b、c、d 4种汉麻籽多肽组分,测定其氨基酸组成,并对其营养和体外结合胆酸盐能力进行了评价。研究结果表明:对于汉麻籽仁多肽组分a、b、c、d,其氨基酸比值系数分值分别为44.08、39.67、48.83、42.16,营养价值一般,限制氨基酸为缬氨酸。体外结合胆酸盐实验结果表明,4种多肽组分都具有潜在降血脂作用,多肽组分d的潜在降血脂作用最强。