本文關(guān)鍵詞： 胃蛋白酶 喜樹堿 秋水仙堿 葛根素 紫外光譜 熒光光譜　出處：《四川大學(xué)》2005年碩士論文　論文類型：學(xué)位論文

【摘要】：胃蛋白酶是動物胃液中主要的蛋白水解酶,具有較強(qiáng)的專一性,催化具有苯丙氨酸,酪氨酸,色氨酸等肽鍵的斷裂,使大分子的蛋白質(zhì)變?yōu)檩^小的多肽。作為一種重要的蛋白水解酶,胃蛋白酶的酶學(xué)性質(zhì),底物專一性,抑制作用等都與其它的蛋白酶不同,具用一定的理論研究價值和應(yīng)用價值。生物堿是一類含氮雜環(huán)的堿性天然有機(jī)物,廣泛存在于植物體內(nèi),在醫(yī)藥上有重要的用途。本文基于生物堿的藥用價值,借助近年來發(fā)展迅速的光譜分析的辦法探討了三種生物堿小分子與胃蛋白酶的相互作用。通過這三種生物堿對胃蛋白酶的動力學(xué)性質(zhì)的影響以及與胃蛋白酶的相互作用的紫外光譜和熒光光譜的研究,對胃蛋白酶在三種小分子影響下的變化及作用機(jī)理作了初步推測。 首先對胃蛋白酶的酶學(xué)性質(zhì)進(jìn)行研究,本實驗采用2000藥典方法,以血紅蛋白作底物,在275nm下以紫外分光光度法測定胃蛋白酶的活力,以每分鐘酶水解血紅蛋白生成一微摩爾的酪氨酸為一個活力單位。以血紅蛋白為底物作酶學(xué)性質(zhì)分析,測得Km值為0.86mmol/L,最適溫度為40℃,最適pH2.0。 喜樹堿,秋水仙堿,葛根素對胃蛋白酶的動力學(xué)影響主要表現(xiàn)在對胃蛋白酶有抑制作用,在不同的底物濃度下分別作三種生物堿對胃蛋白酶的抑制動力學(xué),求得喜樹堿ki值為0.63×10~(-3)mol/L,秋水仙堿ki值為0.976×10~(-3)mol/L,葛根素ki值為1.78×10~(-3)mol/L,三種生物堿的抑制劑類型為非競爭性抑制。抑制作用大小依此為:喜樹堿秋水仙堿葛根素。 通過對喜樹堿,秋水仙堿,葛根素與胃蛋白酶在200-400nm下分別作紫外濃度和時間差譜,發(fā)現(xiàn)喜樹堿,秋水仙堿與胃蛋白酶在3:1的摩爾濃度比,葛根素與胃蛋白酶在4:1的摩爾濃度比具有最明顯的紫外吸收差譜,同時發(fā)現(xiàn)處理時間對三種生物堿與胃蛋白酶作用影響不大,說明它們與胃蛋白酶的結(jié)合可能是一個瞬時過程。
[Abstract]:Pepsin is the main proteolytic enzyme in animal gastric juice, which has strong specificity and catalyzes the breaking of peptide bonds such as phenylalanine, tyrosine and tryptophan. As an important proteolytic enzyme, pepsin's enzymatic properties, substrate specificity, inhibition and so on are different from other proteases. Alkaloids are a kind of natural alkaloids containing nitrogen heterocycles, which are widely used in plants and have important medical applications. This paper based on the medicinal value of alkaloids. The interaction of three kinds of alkaloids with pepsin was studied by means of the rapidly developing spectral analysis in recent years. The effects of these three alkaloids on the kinetic properties of pepsin and the phase with pepsin were discussed. UV and fluorescence spectra of interaction. The changes and mechanism of pepsin under the influence of three kinds of small molecules were preliminarily speculated. Firstly, the enzymatic properties of pepsin were studied. In this experiment, the activity of pepsin was determined by UV spectrophotometry at 275 nm with hemoglobin as substrate and 2000 pharmacopoeia method. The enzyme hydrolyzed hemoglobin per minute to produce a micromole of tyrosine as a unit of activity, hemoglobin as substrate for enzymatic properties analysis, measured km value of 0.86 mmol / L. The optimum temperature is 40 鈩，

本文編號：1469931