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采用乙醇分步沉淀和 DEAE-纤维素柱层析,可从剑麻 Agave sisalana 叶汁中分离到一个均一的蛋白酶组分,其结晶为平面六边形。该酶可为半胱氨酸和 EDTA 所激活,受 PCMB(p-chloromercuribenzoatc)、DTNB(5,5′-dithiobis(2-nitrobenzoic acid))及 Hg~(2+)、Ag~(+)、Cu~(2+)的可逆抑制和碘乙酸(pH 7.5)的不可逆抑制。该酶以酪蛋白为底物时,酶反应的最适 pH 值约为7.5,最适温度为50℃,Km 值为0.0625%酪蛋白,该酶在45℃(含45℃)以下较为稳定。且在6.0—10.0的 pH 值范围内稳定。
A homogeneous protease fraction was isolated from the leaves of Agave sisalana leaves using ethanol fractional precipitation and DEAE-cellulose column chromatography. The crystals crystallized into a flat hexagon. The enzyme is activated by cysteine and EDTA and is affected by PCMB (p-chloromercuribenzoatc), DTNB (5,5’-dithiobis (2-nitrobenzoic acid)) and Hg 2+ Reversible inhibition of Cu ~ (2+) and irreversible inhibition of iodoacetic acid (pH 7.5). When the enzyme is casein, the optimum pH of the enzyme reaction is about 7.5, the optimum temperature is 50 ℃, the Km value is 0.0625% casein, and the enzyme is stable below 45 ℃ (including 45 ℃). And is stable in the pH range of 6.0-10.0.