pH‐induced change in nucleotide binding geometry in the ribonuclease T1‐2'‐guanylic acid complex

FEBS Letters

Tomita, Ken-ichi²  Sugio, Shigetoshi²  Heinemann, Udo¹  Ohishi, Hirofumi²  Saenger, Wolfram¹  Amisaki, Takashi² 

[1] Institut für Kristallographie, Freie Universität Berlin, Takustr. 6, 1000 Berlin 33, FRG;Faculty of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565, Japan

关键词: Ribonuclease T1;    2'-Guanylic acid;    Enzyme-substrate binding;    pH-induced change;    Conformational change;    Crystallography;   

DOI  :  10.1016/0014-5793(85)81127-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

At pH 4.0, the RNase T₁-2'GMP complex (1) crystallizes isomorphously with the isoenzyme complex (2) (Heinemann, U. and Saenger, W., 1982, Nature 299, 27-31). The X-ray structure of 1 was refined with 1.9 Å data to R = 0.195. Polypeptide folding is similar in 1 and 2. However, the sugar pucker of 2'-GMP is 2'-endo (3'endo in 2), and guanine binding involves four hydrogen bonds in 1, which all differ from the two bonds in 2. Phosphate contacts Glu58, Arg77, Tyr38 in 1, but His40 in 2. These changes are not due to differences in sequence between the mother- and isoenzyme (Gln25-Lys) but are associated with pH changes leadingto an inactive enzyme structure.

【 授权许可】

Unknown