Watanabe Y, Yokoi I, Watanabe S, Sugi H, Mori A
Department of Neurochemistry, Okayama University Medical School, Japan.
Life Sci. 1988;43(4):295-302. doi: 10.1016/0024-3205(88)90106-3.
The formation of 2-guanidinoethanol (GEt) from L-arginine (Arg) and ethanolamine (EA) was studied using rat kidney homogenates. Maximum GEt formation was observed between pH 8.7 and 9.1, and the enzyme catalyzing the GEt synthesis was stable between pH 5.6 and 9.1. The rate of GEt formation from Arg and EA by rat kidney homogenates obeyed simple Michaelis-Menten type kinetics. L-Ornithine and glycine inhibited GEt formation by rat kidneys. Both of them inhibited GEt formation in a linear mixed-type inhibitory manner when Arg concentrations were varied at a fixed concentration of EA, while they showed competitive inhibition when EA concentrations were varied at a fixed concentration of Arg. L-Canavanine and guanidinoacetic acid as well as Arg acted as an amidine donor for GEt formation, but L-homoarginine, 3-guanidinopropionic acid and 4-guanidinobutyric acid did not. GEt synthesis was also observed in the rat pancreas. It had almost half of the activity of rat kidney to form GEt. This ratio of kidney to pancreas was approximately equal to that of L-arginine:glycine amidinotransferase (transamidinase, EC 2.1.4.1) in kidney and pancreas. These results suggest that GEt may be synthesized from Arg and EA by a transamidinase catalyzing reaction.
利用大鼠肾脏匀浆研究了由L-精氨酸（Arg）和乙醇胺（EA）生成2-胍基乙醇（GEt）的过程。在pH 8.7至9.1之间观察到GEt的最大生成量，催化GEt合成的酶在pH 5.6至9.1之间稳定。大鼠肾脏匀浆由Arg和EA生成GEt的速率遵循简单的米氏动力学类型。L-鸟氨酸和甘氨酸抑制大鼠肾脏生成GEt。当在固定的EA浓度下改变Arg浓度时，它们均以线性混合型抑制方式抑制GEt生成，而当在固定的Arg浓度下改变EA浓度时，它们表现出竞争性抑制。L-刀豆氨酸、胍基乙酸以及Arg可作为GEt生成的脒基供体，但L-高精氨酸、3-胍基丙酸和4-胍基丁酸则不能。在大鼠胰腺中也观察到了GEt的合成。其生成GEt的活性几乎是大鼠肾脏的一半。肾脏与胰腺的这一比例与肾脏和胰腺中L-精氨酸：甘氨酸脒基转移酶（转脒基酶，EC 2.1.4.1）的比例大致相等。这些结果表明，GEt可能是由转脒基酶催化反应从Arg和EA合成的。
