广东省血红蛋白研究Ⅵ 一例HbG—Coushatta(α_2β_2^(22)Glu→Ata)的结构与功能测定

Guangdong Abnormal Hemoglobin Ⅵ——Structural and Functional Studies of A Case of HbG Coushatta(α_2β_2^(22)Glu—Ala) Found in Guangzhou

1984年我校血红蛋白普查中检出一例电泳慢速血红蛋白,绎肽链裂解、指纹分析、氨基酸组份分析和氨基酸顺序测定确定为β链变异。即在β链22位上的GIu被Ala所取代,这是一例HbG—Coushatta(α_2β_2(^(22)Glu→Ala))。按Benesch法测定其氧亲合力,发现它的氧亲合力比HbA的高。穆斯堡尔谱测定表明这一异常Hb的S值比HbA的大,而其△E_Q值却比HbA的小,说明它所含Fe原子的电子结构有变化。本文对这一异常Hb结构与功能的关系以及穆斯堡尔参数变化的可能机理作了简单的讨论。

During a survey of abnormal hemoglobins (Hb) in Jinan University, Guangzhou, 1984, a slow-moving Hb variant with a mobility similar to that of HbG was found in a student. By using the method of Clegg etal for separation of an abnormal slow-moving β-chain. This abnormal β-chain fraction was collected and digested with TpCK-trypsin, the fingerprint made, and found that the spot βT-3 had disappeared from its normal position. The amino aoid composition of the abnormal peptide was analyzed, the result indicated that one molecule of glutamic acid was missing while one molecule of alanin was present. Amino acid sequence of the abnormal peptide, was determined by Edman degradation method and the DABITC/PITC, double-coupling technique, the result confrmed that it was the glutamic acid residue at position 22 that had been replaced by an alanyl residue. The Hb variant was identified as Hb coushatta. Under the same. conditions, measured by the method of Benerch etal, it was found that Hb Coushatta had higher oxygen affinity than that of HbA. Mossbauer effect of Hb G-Coushatta was quite different from that of HbA under the same conditions, which indicated that the electronic structure of Fe in Hb eoushatla had changed.