抑制剂和激活剂对梨星毛虫中肠蛋白酶活性的影响

旨在研究不同抑制剂和激活剂对梨星毛虫Illiberis pruni中肠蛋白酶活性的影响。利用生化技术分别测定梨星毛虫幼虫不同龄期的4种中肠蛋白酶（总蛋白酶、强碱性胰蛋白酶、弱碱性胰蛋白酶和胰凝乳蛋白酶）活性,进而在最适龄期（4龄幼虫）测定蛋白酶激活剂（EDTA,MgCl₂,EGTA,CaCl₂）和抑制剂（PMSF,TPCK,STI,TLCK,IAA,DTT）对梨星毛虫中肠蛋白酶活性的影响。结果表明：梨星毛虫幼虫中肠总蛋白酶、强碱性胰蛋白酶、弱碱性胰蛋白酶、胰凝乳蛋白酶均在4龄具有最高酶活性。所有试剂均对总蛋白酶有激活作用;5 mmol/L CaCl₂对强碱性胰蛋白酶抑制作用最高;对弱碱性胰蛋白酶有抑制作用的仅有5 mmol/L DTT;对胰凝乳蛋白酶抑制效果最佳的为10 mmol/L EGTA。所筛选的对梨星毛虫主要中肠蛋白酶具有抑制作用的抑制剂,对以昆虫中肠蛋白酶为靶标的绿色害虫防控技术的开发具有参考价值。     

Purification and characterization of a cysteine-like protease from the body wall of the sea cucumber <Emphasis Type="Italic">Stichopus japonicus</Emphasis>

The sea cucumber (Stichopus japonicus) is able to undergo autolysis in response to a variety of environmental and mechanical cues. Within the framework of a long-term study of this phenomenon we have purified a protease from the body wall of the sea cucumber by means of ion-exchange chromatography with DE-52 cellulose and gel filtration chromatography with Sephadex G-100. The final enzyme preparation was nearly homogeneous on polyacrylamide gel electrophoresis, and its molecular weight was estimated to be approximately 35.5 kDa. The purified enzyme exhibited a maximum activity for the hydrolysis of casein at pH 7.0 and 50°C and a remarkable stability at pH 4.0–7.0 and 40–60°C. Based on the inhibition and activation profiles obtained with numerous specific protease inhibitors and an activator, the protease purified from the body wall of the sea cucumber was defined to be a cysteine-like protease.     

Fate of prions in soil: Degradation of recombinant prion in aqueous extracts from soil and casts of two earthworm species

Prions represent the active agent in transmissible spongiform encephalopathy (TSE) diseases and can remain infective to mammals even after prolonged periods in soil. The influence of mesofauna on prion dispersal and degradation in soil, however, remains unknown. In this study the effect of earthworms on the retention/dissemination of TSEs in soil was evaluated using a model recombinant prion protein (recPrP) and aqueous extracts from soil and fresh casts of two earthworm species, Lumbricus terrestris and Aporrectodea caliginosa. Our results showed that earthworm gut-derived enzymes did not enhance the degradation of recPrP in comparison to soil, even though non-prion related proteolytic activity was higher in fresh worm excrements than in soil samples. Complete degradation of recPrP occurred in the aqueous extracts from all samples within up to 6 days at +15 °C. The proteolytic enzymes responsible for degrading recPrP were inhibited by aprotinin and leupeptin and studies in pure cultures suggested these were most probably of soil microbial origin.     

大豆酶解制油蛋白酶的筛选及工艺条件的研究

在以大豆乳液为水解底物进行酶水解来提取大豆油的工艺中,应用蛋白酶水解细胞壁中的蛋白成分使得脂蛋白复合体中的油脂得以释放,从而提高油脂的得油率,通过研究选出破壁能力较强的蛋白酶并优化其水解条件,最后得到最佳水解工艺。     

低值水产品蛋白资源酶解产物的抗氧化性分析和评价

为分析评价水产品蛋白酶解产物活性特性及合适水解蛋白酶类的选择。采用不同的商品化蛋白酶和枯草蛋白酶BPN对市场上常见的经济鱼类白鲢和彩云雕蛋白进行酶解,测定各种酶在水解过程中的水解度,并对酶解产物的抗氧化活性进行了比较分析。结果表明：蛋白酶在水解反应的前20 min内水解度迅速增加,20~120 min之间逐渐达到平衡。复合蛋白酶和水解蛋白酶具有较强的水解能力,其中水解蛋白酶对彩云雕2 h的水解产物最高可达15.92%。白鲢鱼枯草蛋白酶水解液的抗氧化活性最好,其DPPH清除能力为87.11%。不同蛋白酶水解不同的水产品蛋白产生的酶解产物活性肽成分具有明显的差异。     

Development of digestive enzyme activity in larvae of spotted sand bass <Emphasis Type="Italic">Paralabrax maculatofasciatus</Emphasis>. 1. Biochemical analysis

Spotted sand bass Paralabrax maculatofasciatus is a potential aquaculture species in Northwest Mexico. In the last few years it has been possible to close its life cycle and to develop larviculture technology at on pilot scale using live food, however survival values are low (11%) and improvements in growth and survival requires the study of the morpho-physiological development during the initial ontogeny. In this research digestive activity of several enzymes were evaluated in larvae, from hatching to 30 days after hatching (dah), and in live prey (rotifers and Artemia), by use of biochemical and electrophoretic techniques. This paper, is the first of two parts, and covers only the biochemical analysis. All digestive enzyme activities were detected from mouth opening; however the, maximum activities varied among different digestive enzymes. For alkaline protease and trypsin the maximum activities were detected from 12 to 18 dah. Acid protease activity was observed from day 12 onwards. The other digestive enzymes appear between days 4 and 18 after hatching, with marked fluctuations. These activities indicate the beginning of the juvenile stage and the maturation of the digestive system, in agreement with changes that occur during morpho-physiological development and food changes from rotifers to Artemia. All enzymatic activities were detected in rotifers and Artemia, and their contribution to enhancement the digestion capacity of the larvae appears to be low, but cannot be minimised. We concluded that the enzymatic equipment of P. maculatofasciatus larvae is similar to that of other marine fish species, that it becomes complete between days 12 and 18 after hatching, and that it is totally efficient up to 25 dah.     

温度对大菱鲆幼鱼生长、成活率和体内蛋白酶活性的影响

通过温度的变化研究不同温度对大菱鲆幼鱼生长、成活率和消化器官内蛋白酶活性的影响,结果表明,A在温度达到0℃时,幼鱼成活率为30%;4℃以上至20℃时成活率为100%,22~24℃为80%;26℃为40%;当水温达到28℃时,幼鱼成活率为0(20d)。养殖水温在8℃以下时,幼鱼基本不摄食,体重没有增长。12~16℃时,其生长速度随温度的升高而加快,当养殖水温达到20℃时,其生长速度与16℃条件下的生长速度相比较开始下降,达到24℃时,幼鱼生长速度已经明显下降,与12℃条件下的体重增长速度相接近。在8℃之前,幼鱼胃、肠和肝脏等消化器官中的蛋白酶活力单位含量较低。随温度的增加,酶活力单位显著增加,其中胃中的消化酶活力增加最快。     

Rapid degradation of gliadin peptides toxic for coeliac disease patients by proteases from germinating cereals

We report the isolation and characterisation of proteases from germinated wheat, rye and barley, and their ability to degrade gliadin peptides toxic for coeliac patients. It is shown for the first time that these proteases cleave these peptides rapidly into non-toxic fragments with less than nine amino acids. These proteases have distinct advantages when compared to bacterial or fungal proteases, and are promising candidates for the detoxification of gluten containing foods and for oral therapy for celiac patients.