来自大肠杆菌的色氨酸吲哚裂解酶中色氨酸-248和色氨酸-330的环境。

The environments of Trp-248 and Trp-330 in tryptophan indole-lyase from Escherichia coli.

作者信息

Phillips R S, Gollnick P

机构信息

Department of Chemistry, School of Chemical Sciences, University of Georgia, Athens 30602.

出版信息

FEBS Lett. 1990 Jul 30;268(1):213-6. doi: 10.1016/0014-5793(90)81011-c.

DOI:10.1016/0014-5793(90)81011-c

PMID:2200710

Abstract

The two tryptophan residues, Trp-248 and Trp-330, in tryptophan indole-lyase (tryptophanase) from E. coli have been separately mutated to phenylalanine using site-directed mutagenesis. Both single tryptophan mutant enzymes have full catalytic activity, but exhibit different fluorescence and near-UV circular dichroism spectra. These results indicate that Trp-330 is more deeply buried than is Trp-248, and is in a more asymmetric environment. Neither residue reacts with N-bromosuccinimide (NBS), although tryptophan indole-lyase is inactivated by NBS. These results demonstrate that the tryptophan residues in tryptophan indole-lyase are not catalytically essential.

摘要

利用定点诱变技术，已将来自大肠杆菌的色氨酸吲哚裂合酶（色氨酸酶）中的两个色氨酸残基Trp - 248和Trp - 330分别突变为苯丙氨酸。两种单色氨酸突变酶均具有完整的催化活性，但呈现出不同的荧光和近紫外圆二色光谱。这些结果表明，Trp - 330比Trp - 248埋藏得更深，且处于更不对称的环境中。尽管色氨酸吲哚裂合酶会被N - 溴代琥珀酰亚胺（NBS）灭活，但这两个残基均不与NBS反应。这些结果证明，色氨酸吲哚裂合酶中的色氨酸残基并非催化所必需。