표고버섯, Lentinus edodes(Berk.)Sing 중의 가지달린 아미노산 aminotransferase(BCAT)의 enzyme I과 II를 황산암모늄 분별침전, DEAE-cellulose column 크로마토그래피 및 sephadex G-150 겔 여과하여 각각 분리 정제하였다. enzyme I과 II의 동질효소 여부를 규명하기 위하여 enzyme I의 분자량, N-말단, 아미노산 조성, 최적 pH, 최적 온도, $K_m$값, 유기물 및 무기물효과 등을 실험하였다. 이 효소의 겉보기 분자량은 69,000 dalton 이었고, N-말단 아미노산은 glycine이었으며, 음성잔기를 가진 아미노산이 양성잔기를 가진 것보다 7.13% 더 많이 존재하였다. 최적 pH 및 최적 온도는 각각 8.5, $36^{circ}C$ 였으며, $20^{circ}C$ 이하에서 30분 동안 열에 안정하였다. 이 효소는 L-leucine, L-isoleucine 및 L-valine의 기질에 대하여 모두 활성을 보였으며, hydroxylamine, N-ethylmaleimide 및 p-chloromercuribenzoate 등의 유기물과 $Cu^{2+}$, $Hg^{2+}$ and $Fe^{3+}$ 등의 금속이온에 의하여 활성이 억제되었다. 아미노기 공여체인 L-Ieucine과 아미노기 수용체인 $alpha$-ketoglutarate에 대하여 효소활성도 측정시의 조건하에서 측정된 $K_m$값은 각각 2.40 및 0.30mM이었다.
Enzyme I and II of branched chain amino acid aminotransferase (BCAT) in Lentinus edodes (Berk.) Sing was purified by ammonium sulfate saturation, DEAF-cellulose column chromatography and sephadex G-150 gel filtration. We have been studied molecular weight, N-terminal amino acid, composition of amino acids, optimum pH, optimum temperature, $K_m$ value and effect of organic compounds and metal ions about enzyme I, to identify isozyme patterns between enzyme I and II. Apparent molecular weight of enzyme was estimated 69,000 dalton, N-terminal amino acid was determined glycine. The enzyme I was existed as negatively charged amino acids rather than positively charged ones by more than 7.13%. Optimum pH and temperature were found to be 8.5 and $30^{circ}C$, respectively. It was stable for 30 min under$20^{circ}C$. This enzyme showed activity toward L-leucine, L-isoleucine and L-Valine as a substrate. It was Inhibited by both organic compounds of hydroxylamine, N-ethylmaleimideand p-chloromercuribenzoate and metal ions of $Cu^{2+}$, $Hg^{2+}$ and $Fe^{2+}$. The $K_m$ values were determined to be 2.40 mM for L-leucine as a amino group donor, 0.30 mM for $alpha$-keto-glutarate as a amino group acceptor.
