尹潔; 朱軍莉; 傅玲琳; 勵建榮
浙江工商大學(xué)食品與生物工程學(xué)院; 浙江省食品安全重點(diǎn)實(shí)驗(yàn)室

【中文摘要】 通過(NH4)2SO4沉淀、Phenyl Sepharose FF疏水層析分離純化香菇中的γ-谷氨酰轉(zhuǎn)肽酶(γ-Glutamyltranspeptidase,GGT),純化后的GGT的比活力到達(dá)了19.59U/mg。SDS-PAGE分析表明,GGT由分子量分別為28kDa和60kDa的兩個亞基組成。酶學(xué)性質(zhì)試驗(yàn)結(jié)果表明,GGT反應(yīng)的最適溫度為37℃,最適pH值為7.6;金屬離子Na+、K+和Ca2+對酶有激活作用,而Ag+、Cu2+、Zn2+和Fe3+則有抑制作用;試驗(yàn)范圍內(nèi),GGT水解γ-glutamyl-p-nitroanilide的米氏動力學(xué)參數(shù)Km值為2.601μmol/mL,Vmax值為0.0287μmol/min;組成的氨基酸中,Glu和Asp含量較高,Met和Cys含量較低。

【英文摘要】 γ-Glutamyltranspeptidase (GGT) was extracted from Lentinula edodes by ammonium sulfate precipitation and purified by Phenyl Sepharose FF column chromatography. The specificity activity of the purified GGT was 19.59 U/mg,and SDS-PAGE revealed that the enzyme consisted of two subunits of 28 kDa and 60 kDa,respectively. The optimal temperature and pH values for enzyme activity were 37 ℃ and 7.6,respectively. Na+,K+ and Ca2+ exerted a slight activating effect on GGT,whereas Cu2+,Ag+,Zn2+ and Fe3+ inhibited enzyme activity. The rate of γ-glutamyl-p-nitroanilide hydrolysis by purified GGT followed Michaelis-Menten kinetics over the substrate concentration range 50250 mmol/L (Km=2.601 μmol/mL,Vmax=0.0287 μmol/min). Purified GGT contained highest amounts of glutamic and aspartic acids,whereas Cys and Met were present in low amounts.

【中文關(guān)鍵詞】 香菇; γ-谷氨酰轉(zhuǎn)肽酶; 分離純化; 酶學(xué)性質(zhì)
【英文關(guān)鍵詞】 Lentinula edodes; γ-glutamyltranspeptidase; enzyme purification; enzyme properties
【基金】教育部科學(xué)技術(shù)研究重點(diǎn)項(xiàng)目“香菇采后保鮮和加工過程中內(nèi)生甲醛的形成和調(diào)控機(jī)理”(編號:208054)的部分研究內(nèi)容~~

【文獻(xiàn)出處】 食用菌學(xué)報,Acta Edulis Fungi,編輯部郵箱,2009年02期 【DOI】CNKI:SUN:SYJB.0.2009-02-010