达拉斯血红蛋白（α97(G4)天冬酰胺→赖氨酸）：一种高氧亲和力天然突变体的功能特性

Hemoglobin Dallas (alpha 97(G4)Asn-->Lys): functional characterization of a high oxygen affinity natural mutant.

作者信息

Lendaro E, Ippoliti R, Brancaccio A, Bellelli A, Vallone B, Ivaldi G, Sciarratta G V, Castello C, Tomova S, Brunori M

机构信息

CNR, Center of Molecular Biology, University La Sapienza, Rome, Italy.

出版信息

Biochim Biophys Acta. 1992 Oct 13;1180(1):15-20. doi: 10.1016/0925-4439(92)90021-e.

DOI:10.1016/0925-4439(92)90021-e

PMID:1390940

Abstract

Hemoglobin Dallas, an alpha-chain variant with a substitution of lysine for asparagine at position 97(G4), was found to have increased oxygen affinity (p1/2 = 1 mmHg at pH 7.3 and 20 degrees C), diminished cooperativity (n, the Hill coefficient = 1.7) and reduced Bohr effect (about 50%). Addition of allosteric effectors (such as 2,3-diphosphoglycerate, inositol hexakisphosphate and bezafibrate) led to a decrease in oxygen affinity and increase in cooperative energy. Kinetic studies at pH 7.0 and 20 degrees C revealed that (i), the overall rate of oxygen dissociation is 1.4-fold slower than that for HbA and (ii), the carbon monoxide dissociation rate is unaffected. The abnormal properties of this hemoglobin variant can be attributed to a more 'relaxed' T-state.

摘要

达拉斯血红蛋白是一种α链变体，在第97位（G4）的天冬酰胺被赖氨酸取代，发现其具有增加的氧亲和力（在pH 7.3和20℃时p1/2 = 1 mmHg）、降低的协同性（n，希尔系数 = 1.7）和降低的玻尔效应（约50%）。添加变构效应剂（如2,3-二磷酸甘油酸、肌醇六磷酸和苯扎贝特）导致氧亲和力降低和协同能增加。在pH 7.0和20℃下的动力学研究表明，（i）氧解离的总体速率比HbA慢1.4倍，（ii）一氧化碳解离速率不受影响。这种血红蛋白变体的异常特性可归因于更“松弛”的T态。