木瓜蛋白酶水解大豆分离蛋白研究

本文研究了木瓜蛋白酶对大豆分离蛋白的有限水解作用。分析了酶浓度，反应时间，温度，底物浓度，半胱氨酸，异Vc钠，亚硫酸钠浓度等因素对大豆蛋白水解作用的影响。试验得出木瓜蛋白酶水解大豆分离蛋白的较佳条件是酶浓度为8000U/g底物，反应时间150-200min，温度50℃，大豆蛋白浓度为4.5%-8%，半胱氨酸浓度0.25%。     

Characterization and bioactivities of young rice protein hydrolysates

Immature rice was reported to contain higher quantities of bioactive compounds than mature rice. Young rice protein is easy to digest and has hypoallergenic potential, with protein content of 7.2–11.5% compared to rice bran at 9.8%. Few studies have reported on bioactivities and characterization of young rice proteins and their hydrolysates. Bioactivities of native protein and protein hydrolysates of two rice varieties (white rice and colored rice) were characterized and investigated for four development stages (flowery, milky, dough, and mature). Degree of hydrolysis of young rice protein was considerably higher than at the mature stage. Highest DPPH and iron chelating activity were found in alcalase® protein hydrolysate during the flowery-to-milky stage. Iron chelating activity was constant in all development stages because of the low polar amino acid content in rice. The ACE activity of alcalase® protein hydrolysate was higher than native protein at the same development stage, as observed in the milky and dough stages. Inhibitory activity of young rice hydrolysate HepG2 cells was concentration-dependent and not correlated with protein molecular size.     

木瓜蛋白酶水解核桃蛋白的工艺条件优化及水解物抗氧化活性研究

[目的]研究采用木瓜蛋白酶水解核桃蛋白的工艺条件及水解物的抗氧化活性。[方法]采用正交试验法确定木瓜蛋白酶水解核桃蛋白的最适工艺条件,采用Sephadex G-25凝胶色谱分离酶水解物,通过测定羟自由基（OH·）和超氧阴离子自由基清除能力研究了酶水解物的抗氧化活性。[结果]核桃蛋白木瓜蛋白酶水解的最优奈件是温度55℃,底物浓度4％,酶浓度60000U／g,pH值8．0;在水解度达到38．4％时,其酶解产物对羟自由基（OH·）和超氧阴离子自由基（O2·）的清除率分别为22．5％和46．4％。采用Sephadex G-25凝胶柱层析对水解度38．4％的酶水解物进行分离得到了A、B、C和D4个肽片段,其中肽片段c的自由基清除能力最大。[结论]核桃蛋白木瓜蛋白酶水解物具有一定抗氧化活性。     

水解酪蛋白对诱导苜蓿愈伤组织的影响

以两个苜蓿品种新牧1号和新疆大叶苜蓿无菌苗的幼叶为外植体，研究了4种诱导培养基对愈伤组织的影响，增殖培养基中添加水解酪蛋白对愈伤组织增殖的影响，以及分化培养基中KT对愈伤组织分化的影响。结果表明：①叶片愈伤组织诱导培养基以MS＋2，4-D2．00mg／I，＋NAA1．00mg／L＋KT1．00mg／L为宜，新牧1号和新握大叶苜蓿的出愈率分别为100％，95．5％；②增殖培养基中附加CH0．15g／L有利于新牧1号愈伤组织的生长，附加CH1．00g／L有利于新疆大叶苜蓿的愈伤组织的生长；③分化培养培养基中附加KT4．00mg／L，两品种的分化率最高分别为新牧1号25．0％、新疆大叶苜蓿13．2％。     

Nutritive value of squid and hydrolyzed protein supplement in shrimp feed

Though some protein sources like squid and protein hydrolysates are assumed as growth enhancers for shrimp, little is known about the biochemical basis of this phenomenon. Low, heat-dried squid (Dosidicus gigas) (SQ) and two commercial protein hydrolysates from fish (FH) and krill (Euphasia sp.) (KH) were assayed in feeding trials with Penaeus vannamei. Feeds were prepared with the tested proteins at 3%, 9%, and 15% of the total crude protein. A total of nine experimental feeds plus a commercial one as control (C32) were tried. Additionally, digestibility in vivo and in vitro was evaluated. Survival was not different among groups. Weight gain of shrimp and total and specific proteolytic activity for trypsin and chymotrypsin were affected by type and quantity of supplemented protein. In vivo and in vitro digestibilities were also influenced by the source and quantity of the protein supplement. Shrimp fed feed with FH at 3% protein supplementation grew more than those fed with higher supplementations. Groups fed SQ had similar results as those fed FH, and gained more weight when fed the lowest SQ quantity. SDS-PAGE showed a large concentration of small peptides in SQ, which may explain results similar to FH. KH enhanced shrimp growth at all supplementations and had a lower degree of hydrolysis (DH) than FH. SQ also demonstrated good growth performance, but better at the lower supplementation, probably because of the presence of small peptides and possibly free amino acids from protein hydrolyzed by endogenous enzymes in the squid mantle. We conclude that hydrolyzed protein is a good supplement for shrimp feeds, but it must meet specific requirements for adequate assimilation.     

啤酒废酵母酶解生产橘小实蝇引诱蛋白研究

[目的]优化啤酒废酵母酶解生产橘小实蝇引诱蛋白的条件。[方法]采用室外小笼子生物测定法,通过正交试验设计对啤酒废酵母酶解生产橘小实蝇引诱蛋白的影响因素(酵母浓度、酶量、水解温度、水解时间、水解pH和水解产物pH)进行了优化。[结果]将酵母母液稀释3倍后加入15.0 g/kg木瓜蛋白酶,在pH 6.5、温度67.5℃条件下保温水解24 h得到的水解蛋白于pH 8.5时对橘小实蝇雄性的引诱活性最强,水解27 h对橘小实蝇雌性的引诱活性最强。[结论]为开发橘小实蝇蛋白诱剂提供了理论依据。     

3种菌株产木聚糖酶同工酶及其酶解产物的比较

探讨3种菌株所产木聚糖酶组分及其酶解产物的差异,为酶制剂和功能低聚木糖的研发和应用提供理论依据。采用SDS-PAGE电泳,研究黑曲霉C71、康宁木霉M46及XYNB重组工程菌G81所产的木聚糖酶同工酶。结果表明,C71、M46及G81分别产3种、4种和2种木聚糖酶同工酶;以桦木木聚糖为底物,在酶添加量为70U/g、底物20g/L、反应时间10h条件下进行酶解,采用TLC及HPLC分析酶解产物。TLC结果表明,C71和M46酶解液中含有木糖、木二糖和木三糖;G81酶解液中含有木二糖、木三糖和木四糖。HPLC结果表明,C71酶解液中木糖、木二糖和木三糖的质量浓度分别为2.4、1.3和1.7g/L;M46酶解液中木糖、木二糖和木三糖的质量浓度分别为1.5、1.8和2.1g/L;G81酶解液中木二糖、木三糖和木四糖的质量浓度分别为2.6、2.7和1.4g/L。不同菌株所产木聚糖酶组分及其酶解产物存在差异,低聚木糖的研发应根据酶学特性,选择不同的单一或复合酶制剂。     

不同蛋白酶水解鹿血效果比较的研究

以鹿血蛋白水解度(DH)及水解物的还原能力和对DPPH自由基的清除率为指标,在最适条件下,选用碱性蛋白酶、中性蛋白酶和风味蛋白酶水解鹿血的结果表明:碱性蛋白酶水解鹿血的水解度及其鹿血水解物的还原能力和对DPPH自由基的清除率都为最高。     

马铃薯渣水解液的反渗透浓缩研究

[目的]探讨反渗透法浓缩马铃薯渣水解液的可行性。[方法]将反渗透技术应用于马铃薯渣水解液的浓缩,研究其浓缩工艺、过程及效果。[结果]适宜的反渗透操作条件为温度30℃,操作压力0.6～0.7 MPa,膜面流速30 ml/min。该条件下马铃薯渣水解液可由5.0°Bx浓缩到19.5°Bx。浓缩以后水解液的总质量为原来的25.03%,质量分数提高了3.9倍,水分减少了78.62%。在40℃下,0.2%NaOH和0.2%十二烷基苯磺酸钠的混合溶液可作为浓缩操作后反渗透膜的清洗剂,恢复系数高达96%。[结论]该浓缩工艺耗能低,操作简便,自动化程度高,容易实现工业化。     

玉米秸秆水解液脱毒处理发酵生产酒精研究

为了找到适宜的玉米秸秆生产酒精工艺,采用水热处理后的玉米秸秆固体与水解液进行酒精同步糖化发酵,研究了预水解后不同pH值以及饱和生石灰法脱毒相结合对酒精发酵的影响。结果表明:当pH值在4.8时,加入100%水解液,由于抑制作用,醪液中酒精质量浓度仅为0.31 g/L(酒精得率9.48%)。预水解后将pH值从4.8分别调整到5.5、6.0和6.5后,酒精得率都有明显提高,最高为pH值5.5时,酒精质量浓度为10.67 g/L。将水解液经过饱和生石灰法脱毒处理,预水解后重新将pH值调整为5.5,酒精质量浓度达到了10.96 g/L(酒精得率57.9%)。与初始pH值4.8时相比,酒精得率提高了近6倍。