Garel M C, Lemarchandel V, Prehu M O, Calvin M C, Arous N, Rosa R, Rosa J, Cohen-Solal M
Unité INSERM-U91, Hôpital Henri Mondor, Créteil, France.
Biomed Biochim Acta. 1990;49(2-3):S166-71.
2,3-bisphosphoglycerate mutase is a multifunctional enzyme which catalyses in red blood cells the synthesis and the degradation of 2,3-bisphosphoglycerate, the allosteric effector of hemoglobin. In order to study the structure-function relationships in BPGM, an expression vector was constructed which yielded an active protein, but with a modified electrophoretic mobility, due to a non-blocked N-terminal residue. Using site directed mutagenesis, mutants were produced with shortened chains. Results indicated the importance of residues 252-256 for the function. A natural deficient mutant with the substitution 89 Arg----Cys was described. Artificial mutant with the same substitution reproduced the same defect, as well as mutants Arg----Gly and Arg----Ser, indicating the key role of Arg 89 in the enzymatic mechanism.
2,3-二磷酸甘油酸变位酶是一种多功能酶，它在红细胞中催化2,3-二磷酸甘油酸（血红蛋白的变构效应剂）的合成与降解。为了研究二磷酸甘油酸变位酶（BPGM）的结构-功能关系，构建了一种表达载体，该载体产生一种活性蛋白，但由于N端残基未封闭，其电泳迁移率发生了改变。利用定点诱变技术，产生了链缩短的突变体。结果表明252-256位残基对功能很重要。描述了一种天然缺陷型突变体，其89位精氨酸被替换为半胱氨酸。具有相同替换的人工突变体再现了相同的缺陷，精氨酸被替换为甘氨酸和丝氨酸的突变体也是如此，这表明89位精氨酸在酶促机制中起关键作用。
