Tautomeric state of α‐sarcin histidines. Nδ tautomers are a common feature in the active site of extracellular microbial ribonucleases

FEBS Letters

Garcı́a‐Mayoral, Ma Flor¹  Bruix, Marta¹  Gavilanes, José G²  Rico, Manuel¹  Laurents, Douglas V¹  Martı́nez del Pozo, Alvaro²  Pérez-Cañadilllas, José Manuel¹ 

[1] Departamento de Espectroscopı́a y Estructura Molecular, Instituto de Quı́mica Fı́sica ‘Rocasolano’, CSIC, Serrano 119, 28006 Madrid, Spain;Departamento de Bioquı́mica y Biologı́a Molecular I, Facultad de Quı́mica, Universidad Complutense, 28040 Madrid, Spain

关键词: Histidine tautomer;    pK a;    α-Sarcin;    Ribonuclease;    Ribotoxin;   

DOI  :  10.1016/S0014-5793(02)03844-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown