小鼠浆细胞瘤中两种tRNA甲基转移酶的一些分子和动力学特性研究。

A study of some molecular and kinetic properties of two tRNA methyltransferases from mouse plasmocytoma.

作者信息

Nau F, Pham-Coeur-Joly G, Dubert J M

出版信息

Eur J Biochem. 1983 Feb 1;130(2):261-8. doi: 10.1111/j.1432-1033.1983.tb07145.x.

DOI:10.1111/j.1432-1033.1983.tb07145.x

Abstract

A tRNA(adenine-1)methyltransferase and a tRNA(cytosine-5)methyltransferase have been partially purified from mouse plasmocytoma MOPC 173. Their apparent Mr are 200000-230000 and 110000-140000, respectively, as determined by gel filtration and density gradient centrifugation. Both enzymes exhibit maximum activity in the presence of high concentrations of monovalent cations (0.175 M and 0.25 M KCl, respectively) and in the absence of magnesium. Their kinetic constants have been determined at various KCl concentrations, with several tRNA species as substrates. These constants may differ by more than one order of magnitude, depending upon the substrate used, and they are strongly dependent upon the ionic concentration as well. The possibility that the tRNA(adenine-1)methyltransferase from mouse plasmocytoma is different from the homologous enzyme purified from a normal rat tissue [Glick, J. M. and Leboy, P. S. (1977) J. Biol. Chem. 252, 4790-4795] is discussed.

摘要

已从小鼠浆细胞瘤MOPC 173中部分纯化出一种tRNA（腺嘌呤-1）甲基转移酶和一种tRNA（胞嘧啶-5）甲基转移酶。通过凝胶过滤和密度梯度离心测定，它们的表观分子量分别为200000 - 230000和110000 - 140000。两种酶在高浓度单价阳离子（分别为0.175 M和0.25 M KCl）存在且无镁离子的情况下表现出最大活性。已在不同KCl浓度下，以几种tRNA种类为底物测定了它们的动力学常数。这些常数可能因所用底物不同而相差一个以上数量级，并且它们也强烈依赖于离子浓度。文中讨论了从小鼠浆细胞瘤中分离出的tRNA（腺嘌呤-1）甲基转移酶与从正常大鼠组织中纯化出的同源酶[Glick, J. M.和Leboy, P. S.（1977年）《生物化学杂志》252, 4790 - 4795]是否不同的可能性。