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pH‐induced change in nucleotide binding geometry in the ribonuclease T 1 ‐2'‐guanylic acid complex
Author(s) -
Sugio Shigetoshi,
Amisaki Takashi,
Ohishi Hirofumi,
Tomita Ken-ichi,
Heinemann Udo,
Saenger Wolfram
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)81127-3
Subject(s) - hydrogen bond , chemistry , nucleotide , guanine , crystallography , ribonuclease t1 , rnase p , folding (dsp implementation) , ribonuclease , stereochemistry , biochemistry , molecule , rna , gene , organic chemistry , electrical engineering , engineering
At pH 4.0, the RNase T 1 ‐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.