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Three‐dimensional structure of a barnase‐3'GMP complex at 2.2Å resolution
Author(s) -
Guillet Valéric,
Lapthorn Adrian,
Mauguen Yves
Publication year - 1993
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(93)80259-w
Subject(s) - barnase , chemistry , dimer , nucleotide , stereochemistry , hydrogen bond , base pair , molecular replacement , crystallography , binding site , molecule , active site , rna , dna , biochemistry , catalysis , crystal structure , ribonuclease , organic chemistry , gene
Barnase has been co‐crystallized at neutral pH with its natural product the 3'‐guanylic acid. The X‐ray structure was solved by molecular replacement methods and refined to a final R ‐factor of 18.7%. The protein folding is essentially the same as that of the native form. The base recognition site is almost identical to that of the homologous binase‐3'GMP complex, but the nucleotide is bound in a productive binding mode for a substrate with a syn glycosyl torsion angle allowing the general base Glu 73 to hydrogen bond with the 2'O of the nucleotide as is assumed in the classical catalytic mechanism. The two molecules of the asymmetric unit form a dimer and the positions of the two nucleotides partially mimic the interaction of the RNA with the enzyme, one of the inhibitors being located in a secondary subsite.