Lee Geun Taek, Kim Woo Jeung, Cho Young Dong
Department of Biochemistry, Yonsei University, 134 Shinchon-Dong, Seodaemoon-Ku, Seoul, South Korea.
Phytochemistry. 2002 Dec;61(7):781-9. doi: 10.1016/s0031-9422(02)00401-6.
Three-day-old soybean (Glycine max) seedlings were exposed to 0.4 M sorbitol solution for 4 h to induce amidinotransferase activity, with the corresponding enzyme being purified to homogeneity by chromatographic separation on DEAE-Sephacel, Sephacryl S-300 and L-arginine Sepharose 4B. The purified enzyme used L-arginine and L-glycine as the major donor/acceptor of the amidino group, respectively, with formation of guanidinoacetic acid and ornithine products being confirmed by ESI-MS. The enzyme is a tetrameric protein having a molecular mass of 240,000 Da, whose thiol group is needed for enzymatic activity. The K(M)s for arginine and glycine were 3.8 and 0.89 mM, respectively, with optimal temperature and pH being 37 degrees C and 9.5, respectively. The soybean amidinotransferase could be indirectly involved in nitrogen metabolism, as suggested by the observation that arginine:glycine amidinotransferase in soybean axes is indirectly involved in putrescine biosynthesis and displays feedback control at high levels of an endogenous regulator, putrescine.
将三天大的大豆（Glycine max）幼苗置于0.4 M山梨醇溶液中4小时以诱导脒基转移酶活性，相应的酶通过在DEAE-琼脂糖凝胶、Sephacryl S-300和L-精氨酸琼脂糖凝胶4B上的色谱分离纯化至均一。纯化后的酶分别以L-精氨酸和L-甘氨酸作为脒基的主要供体/受体，通过电喷雾电离质谱（ESI-MS）确认形成了胍基乙酸和鸟氨酸产物。该酶是一种分子量为240,000 Da的四聚体蛋白，其酶活性需要巯基。精氨酸和甘氨酸的米氏常数（K(M)）分别为3.8和0.89 mM，最适温度和pH分别为37℃和9.5。大豆轴中的精氨酸：甘氨酸脒基转移酶间接参与腐胺生物合成，并在高水平内源性调节剂腐胺存在时表现出反馈控制，由此推测大豆脒基转移酶可能间接参与氮代谢。
