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Tautomeric state of α‐sarcin histidines. Nδ tautomers are a common feature in the active site of extracellular microbial ribonucleases
Author(s) -
Pérez-Cañadilllas José Manuel,
Garcı́aMayoral Ma Flor,
Laurents Douglas V,
Martı́nez del Pozo Alvaro,
Gavilanes José G,
Rico Manuel,
Bruix Marta
Publication year - 2003
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/s0014-5793(02)03844-9
Subject(s) - tautomer , histidine , active site , rnase p , chemistry , imidazole , ribonuclease , binding site , biochemistry , stereochemistry , enzyme , rna , gene
Extracellular fungal RNases, including ribotoxins such as α‐sarcin, constitute a family of structurally related proteins represented by RNase T1. The tautomeric preferences of the α‐sarcin imidazole side chains have been determined by nuclear magnetic resonance and electrostatic calculations. Histidine residues at the active site, H50 and H137, adopt the Nδ tautomer, which is less common in short peptides, as has been found for RNase T1. Comparison with tautomers predicted from crystal structures of other ribonucleases suggests that two active site histidine residues with the Nδ tautomer are a conserved feature of microbial ribonucleases and that this is related to their ribonucleolytic function.