Department of Chemistry "Paolo Corradini," University of Naples "Federico II," Complesso Universitario Monte S. Angelo, Italy.
IUBMB Life. 2011 May;63(5):295-303. doi: 10.1002/iub.446. Epub 2011 Apr 13.
Spectroscopic and crystallographic evidence of endogenous (His) ligation at the sixth coordination site of the heme iron has been reported for monomeric, dimeric, and tetrameric hemoglobins (Hbs) in both ferrous (hemochrome) and ferric (hemichrome) oxidation states. In particular, the ferric bis- histidyl adduct represents a common accessible ordered state for the β chains of all tetrameric Hbs isolated from Antarctic and sub-Antarctic fish. Indeed, the crystal structures of known tetrameric Hbs in the bis-His state are characterized by a different binding state of the α and β chains. An overall analysis of the bis-histidyl adduct of globin structures deposited in the Protein Data Bank reveals a marked difference between hemichromes in tetrameric Hbs compared to monomeric/dimeric Hbs. Herein, we review the structural, spectroscopic and stability features of hemichromes in tetrameric Antarctic fish Hbs. The role of bis-histidyl adducts is also addressed in a more evolutionary context alongside the concept of its potential physiological role.
已有报道称，在亚铁（血质）和高铁（血质）氧化态下单体、二聚体和四聚体血红蛋白（Hb）的第六配位位置上存在内源性（His）配位的光谱和晶体学证据。特别是，高铁双组氨酸加合物代表了从南极和亚南极鱼类中分离出的所有四聚体 Hb 的β链的常见可及有序状态。事实上，已知处于双 His 状态的四聚体 Hb 的晶体结构的特征在于α和β链的不同结合状态。对蛋白质数据库中储存的球蛋白结构的双组氨酸加合物的整体分析表明，与单体/二聚体 Hb 相比，四聚体 Hb 中的血质在结构上存在明显差异。本文综述了四聚体南极鱼类 Hb 中血质的结构、光谱和稳定性特征。还从更进化的角度以及其潜在生理作用的概念来讨论双组氨酸加合物的作用。
