豆类胰蛋白酶抑制剂研究进展

胰蛋白酶抑制剂是一种在农业、医学及食品科技等多个领域具有重要用途的蛋白质或多肽类。豆类种子中含有丰富的胰蛋白酶抑制剂,并且因品种而异,因而引发了对豆类胰蛋白酶抑制剂的广泛研究。介绍了国内外豆类胰蛋白酶抑制剂的研究进展,从分类及结构特征、酶学特性、提取纯化、活性测定及功能特征五个方面进行综述,并对豆类胰蛋白酶抑制剂的应用前景和存在的问题进行分析,以期为豆类胰蛋白酶抑制剂的进一步研究提供参考。     

STI的抑制作用及茶多酚作用下STI的失活探讨

大豆中的两种主要的胰蛋白酶抑制剂对胰蛋白酶的活性有很强的抑制作用,随着胰蛋白酶抑制剂的增加,胰蛋白酶活性几科能完全被抑制;茶多酚能有效地和胰蛋白酶抑制剂络合而使抑制剂对胰蛋白酶的抑制作用减弱,同时研究表明茶多酚络合失活胰蛋白酶抑制剂还受温度的影响。     

生物法失活大豆胰蛋白酶抑制剂的研究

对生物法失活大豆腋蛋白酶抑制剂进行了研究。测定了豆制品中胰蛋白酶抑制剂的活性;比较了外源蛋白酶失活胰蛋白酶抑制剂的能力,确定了碱性蛋白酶失活胰蛋白酶抑制剂的最优条件为pH值8.88～9.05、温度43.40～44.70℃、酶用量10.44～11.29μL/g、底物浓度6.51%～7.18%。以发芽12h的大豆加工的熟豆乳中胰蛋白酶抑制剂活性降低了83.2%。保加利亚乳杆菌(Lb)、米黑毛霉(M.M)和米根霉(R.O)发酵能有效失活豆乳中的胰蛋白酶抑制剂活性。     

胰蛋白酶抑制剂及其抗肿瘤活性研究进展

简要综述近年来胰蛋白酶抑制剂特别是水生生物胰蛋白酶抑制剂的制备及其抗肿瘤活性方面的研究进展，并对今后的研究方向作了展望。     

豆类胰蛋白酶抑制剂亚基特性研究

本研究选取豌豆、绿豆、豇豆、芸豆、红小豆、蚕豆、黑大豆、鹰嘴豆、黎豆、苦豆10种豆,测得10种豆中胰蛋白酶抑制剂(trypsin inhibitor,TI)含量范围为47.4~148.9 TIU/g,苦豆和品红05200的含量最高,分别为148.9、121.8 TIU/g。Gelatin-PAGE活性染色表明10种豆的亚基数目范围为5~13个,品种间TI亚基种类、丰度存在一定差异。通过极端热、酸、碱、盐、振荡条件分别处理10种豆粉粗提液,在亚基层面分析不同豆类胰蛋白酶抑制剂的稳定性特征,为进一步探究胰蛋白酶抑制剂稳定性机理提供初步结构数据,为豆类在食品加工及饲料养殖方面提供指导。     

枯草杆菌蛋白酶对大豆胰蛋白酶抑制剂的水解钝化研究

研究了枯草杆菌蛋白酶(Subtilisin)对大豆胰蛋白酶抑制剂(STI)酶解活性的影响。实验在50℃,pH7.5条件下反应1h,并以BAPNA为底物,采用改进的方法测定枯草杆菌蛋白酶对大豆胰蛋白酶抑制剂的水解钝化程度,用SDS-PAGE方法和分子排阻色谱法研究其蛋白酶钝化敏感性。结果证明,枯草杆菌蛋白酶可以水解大部分的抑制剂,并通过SDS-PAGE进一步证实了比色法得出的结论。而由分子排阻色谱图可以分析得出抑制剂经枯草杆菌蛋白酶酶解后,活性降低。分析认为,可能是由于抑制剂中二硫键被打断使得其结构发生改变,同时生成大量复杂的小分子多肽物质。因此,可以推断大豆胰蛋白酶抑制剂的稳定性与二硫键的存在有关。     

芸豆籽粒中胰蛋白酶抑制剂的研究进展

芸豆是一种高钾、高镁、低钠的优质食品加工原料,其营养成分丰富,含有蛋白质、碳水化合物、矿物质、维生素等,芸豆胰蛋白酶抑制剂不仅是抗营养因子还是生理活性蛋白,在限制芸豆有效利用的同时还有其独特生理功能。本文介绍了芸豆胰蛋白酶抑制剂的结构、性质、提取、纯化及其功能作用,同时概述了部分加工技术对芸豆胰蛋白酶抑制剂的影响,旨在为芸豆胰蛋白酶抑制剂的研究提供理论基础及为深加工技术的选择提供理论指导。     

热处理时间和压力对豆浆胰蛋白酶抑制剂的影响

分别研究了不同热处理时间和不同处理压力下,豆浆中胰蛋白酶抑制剂活性变化。研究结果表明,常压下当热处理时间达到15min时,豆浆中胰蛋白酶抑制剂的活性下降到2.91mg/g。在30k Pa下,当热处理时间达到5min时,豆浆中胰蛋白酶抑制剂的活性下降到1.62mg/g。在热处理时间为5min处理压力达到90k Pa时,豆浆中胰蛋白酶抑制剂的活性下降到0.47mg/g。因此,从胰蛋白酶抑制剂角度考虑,30k Pa处理5min的加工工艺能大幅提高豆浆的安全性和品质。     

豆制品中胰蛋白酶抑制剂的研究

对豆制品中胰蛋白酶抑制剂活性进行了调查 ,发现水解蛋白、乳用蛋白、组织蛋白、水豆腐、干豆腐中胰蛋白酶抑制剂活性均被钝化了 90 %以上 ;对腐乳、豆酱中胰蛋白酶抑制剂活性进行检测 ,结果未检出。无糖豆粉、×××豆粉、豆浆以及内酯豆腐中胰蛋白酶抑制剂钝化率低于90 %。比较了 3种热处理方式对胰蛋白酶抑制剂的钝化效果 ,得到巴氏杀菌可钝化胰蛋白酶抑制剂1 4 0 7% ;高压杀菌可钝化 91 1 0 % ,超高温灭菌可钝化 6 5 90 %。     

大豆胰蛋白酶抑制剂的提取纯化及其对凡纳滨对虾类胰蛋白酶的抑制作用

凡纳滨对虾的虾头中类胰蛋白酶活性高,死后自溶引起的组织软化大大降低了其商品价值。为了减少品质下降带来的不利影响,通过大豆胰蛋白酶抑制剂来抑制凡纳滨对虾的类胰蛋白酶从而达到提高品质的目的。首先,通过30%~80%硫酸铵沉淀、Q-Sepharose F.F阴离子交换层析和Sephacryl S-100凝胶过滤层析从凡纳滨对虾中提取了类胰蛋白酶,其分子质量为32.6 k Da。通过粉碎、脱脂、0.15 mol/L Na Cl提取,再进行热变性、超滤、Sephacryl S-100凝胶过滤层析纯化得到大豆胰蛋白酶抑制剂,该抑制剂分子量为16 k Da,得率为28.95%,纯化倍数达12.51,为电泳纯。实验结果表明,该抑制剂能抑制凡纳滨对虾类胰蛋白酶的活性,其抑制类型为不可逆抑制。     

多糖降血糖活性构效关系及作用机制研究进展

糖尿病是以高血糖为特征的代谢疾病，发病率逐年攀升，而以西药为主的治疗方式存在一定的副作用，这促使人们将目光转向天然的活性物质。多糖作为一种安全、低毒的天然物质，具有多种生物活性。降血糖活性是多糖的重要活性之一，极具开发潜力。本文从分子质量、单糖组成、糖苷键、高级结构和基团等方面综述了多糖降血糖活性与其结构的关系，并总结了多糖降血糖的作用机制，分析目前研究存在的问题，同时对未来研究的方向进行了总结和展望。     

Response of intestinal proteinase activities to the feeding of isolated winged bean (Psophocarpus tetragonolobus) and soya bean (Glycine max) trypsin inhibitors in rats

The antinutritional activities of trypsin inhibitors (TIs) were compared between winged beans (Psophocarpus tetragonolobus) and soya beans (Glycine max). The inhibitors of the two beans were isolated by trypsin‐bound Sepharose 4B, and 50 mg of lyophilised powders were intubated intragastrically into 24 h fasted rats. The activities of trypsin and chymotrypsin were compared after 30, 60 and 180 min in the washings of the upper, middle and lower parts of the small intestine. The elution profiles of TI and non‐TI compounds in the affinity chromatography were similar in the two beans, and the antitryptic activities were concentrated 5.5 and 6.2 times (based on specific activity) for winged beans and soya beans respectively. Regardless of the TI fed to rats, trypsin activity in the upper intestine was suppressed to almost undetectable levels at 30 and 60 min after intubation. The activities in the middle and lower intestines were also substantially lowered when rats were fed winged bean TI, and significant differences were detected at 30 and 60 min after intubation when compared with rats fed soya bean TI. However, at 180 min after feeding, no differences were found in the trypsin activity in any gut segments. Similar inhibitory properties of isolated TIs were observed in chymotrypsin activities in the small intestine. The results suggest that winged bean TI may have greater inhibitory activity on the intestinal proteinase compared with soya bean TI. © 2001 Society of Chemical Industry     

Heat stability of trypsin inhibitors in tropical root crops and rice and its significance for nutrition

The heat stability of trypsin inhibitors from rice (Oryza sativa L), sweet potato (Ipomoea batatas (L) Lam), taro (Colocasia esculenta var esculenta (L) Schott), giant taro (Alocasia macrorrhiza (L) G Don) and giant swamp taro (Cyrtosperma chamissonis (Schott) Merr) was studied. Rice trypsin inhibitor (TI) occurred only in the germ, so it is absent from white rice. Taro, giant taro and giant swamp taro (but not rice or sweet potato) showed an initial large increase (one- to tenfold) in the amount of TI present on heating at about 80°C. The heat release mechanism, which was accompanied by a change to a rubbery texture in the food, amounted to a breakdown of the cellular structure making TI available for extraction. Such heat release of TI would cause partially cooked food to be deleterious for human consumption. Brown rice, sweet potato, taro and giant swamp taro contained moderate amounts of TI, which was fully inactivated when the boiled or baked food was soft enough to eat. Giant taro, however, contained 10–100 times as much TI (which in this case also inhibited chymotrypsin) as the other foods, and a boiling time of at least 30 min was needed for its inactivation.     

Trypsin inhibitor activity in vicia faba beans

Extracts of mature green, dry and germinated Vicia faba beans depressed the trypsin activity of casein. Germination of Vicia faba beans (for 60 h) lowered the trypsin inhibitor (TI) activity. 0.171M Saline was the most efficient extractant for the TI. Minimal amounts of the TI were extracted in the pH range 4 to 5. The TI of Vicia faba beans was undialysable. The inhibitor activity originated in the seeds at the beginning of pod formation and increased with development of maturity. TI was active only towards trypsin and inactive towards papain, rennin and pepsin. Chromatographing Vicia faba bean proteins, possessing antitryptic activity, on a column of DEAE-cellulose yielded six peaks, all of which possessed antitryptic activity.     

山药多糖结构、生物活性及其机制研究进展

山药是一种重要的药食同源植物,富含多糖、尿囊素、皂苷等多种活性成分,多糖作为其主要的活性成分,具有抗氧化、抗衰老、抗肿瘤、免疫调节、降血糖、降血脂等功效,在保健食品和药品的开发方面具有广阔的应用前景。山药多糖的结构复杂,其单糖组成、分子质量、糖苷及糖链结构对其生物活性具有很大的影响。因此,探究山药多糖的结构特性对揭示其生物活性机制具有重要意义。本文介绍了山药多糖的结构特性,阐述了山药多糖的生物学活性机制,同时探讨了山药多糖结构特性与其生物学活性之间的关系,以期为山药应用于保健食品、药品等领域提供理论支持。     

北沙参多糖的提取工艺、理化性质和生物活性研究进展

北沙参是伞形科植物珊瑚菜的干燥根,为常用药食两用资源。北沙参多糖作为北沙参主要成分之一,具有良好的生物活性。北沙参多糖的提取分为溶剂提取和辅助提取两大类,然而不同的提取方法的多糖得率、结构及生物活性不尽相同,介绍了其总糖含量、特征官能团、分子量、单糖组成、糖苷键构型等理化性质。目前对北沙参多糖的生物活性研究主要集中在免疫调节、抗氧化、抗肿瘤、抗炎及降血糖等方面,在医药、保健功能食品等领域有着良好的前景。本综述就国内外学者对北沙参多糖的提取工艺、分离纯化、结构特征及生物活性研究进行了系统性的总结和归纳,同时也指出了北沙参多糖的高级结构、作用机制及构效关系尚不明确的问题,为其深入研究及有效开发利用提供科学参考。     

DESTRUCTION OF POTATO PEEL TRYPSIN INHIBITOR BY PEELING AND EXTRUSION COOKING

Potato peels, a by-product of potato processing, can serve as a source of concentrated dietary fiber, but potato trypsin inhibitors (TI) in peels could reduce nutritional quality. Peels prepared by two methods (abrasion or steam) were extruded at 110C or 150C with feed moistures of either 30% or 35%. Prior to extrusion, abrasion and steam peels contained 45.57 and 8.06 TIU/g, respectively. Extrusion reduced TI activity by 75–85% in abrasion peels, but no reductions were observed for steam peels. TI may not pose a nutritional problem for steam peels with or without extrusion. Abrasion peels should be extruded, or processed by another thermal method, prior to use in foods.     

Effect of Cooking on Firmness, Trypsin Inhibitors, Lectins and Cystine/Cysteine content of Navy and Red Kidney Beans (Phaseolus vulgaris)

The effect of cooking on firmness, trypsin inhibitor (TI) and lectin activities, and cystine/cysteine (Cys) of navy and red kidney beans was investigated. Beans were soaked and cooked in an open-kettle at various temperatures and periods. Navy beans canned by two methods were used for comparisons with the open-kettle cooked beans. The TI activity, lectin activity and Cys content decreased with increasing temperature and/or period. Under some of the cooking conditions, less than 5.5% and 0.1% of TI and lectin activities, respectively, were retained, though the firmness of beans was palatable. Canned navy beans did not have lectin activity but had less than 5% residual TI activity.     

转基因食品胰蛋白酶抑制剂活性的测定

目的通过测定转基因食品的胰蛋白酶抑制剂活性,为建立转基因食品营养评价标准提供数据。方法首先通过探讨胰蛋白酶-底物-胰蛋白酶抑制剂的剂量反应关系,建立转基因食品胰蛋白酶抑制剂活性测定的最佳反应体系,并以此为基础分析了部分转基因玉米、大豆的胰蛋白酶抑制剂活性及与亲本食品的差别。结果所检转基因食品胰蛋白酶抑制剂活性大多与亲本食品差别不大,尽管个别产品出现胰蛋白酶抑制剂活性增高或降低现象,但都在可接受范围。结论在规范检测技术前提下加强对非转基因食品基础数据建设对制定转基因食品营养评价标准十分必要。     

植物多糖免疫调节作用机制研究进展

多糖作为生物体内广泛存在的一类生物大分子物质,是构成生物体的重要物质, 同时还具有抗病毒、抑菌、抗肿瘤和降血糖等重要的生理活性。目前,植物多糖提高机体免疫力的功能研究引起了国内外学者的广泛关注;越来越多的研究表明,植物多糖可作为一种天然药物被广泛使用。本文综述了植物多糖对固有性免疫、适应性免疫、细胞因子和机体免疫信息等方面的免疫调节和作用机制,及植物多糖的结构特征与构效关系研究,展望了植物多糖在促进细胞因子的分泌、促进抗体生成和红细胞免疫功能理论基础研究的前景和发展方向,以期为植物多糖免疫活性研究提供理论参考,并对植物多糖免疫调节机制的更深层次研究提供思路。