Interactions of pig liver serine hydroxymethyltransferase with methyltetrahydropteroylpolyglutamate inhibitors and with tetrahydropteroylpolyglutamate substrates.
Interactions of pig liver serine hydroxymethyltransferase with methyltetrahydropteroylpolyglutamate inhibitors and with tetrahydropteroylpolyglutamate substrates.
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猪肝丝氨酸羟甲基转移酶与甲基四氢蝶酰聚谷氨酸抑制剂和四氢蝶酰聚谷氨酸底物的相互作用。
DOI：
10.1021/bi00535a019
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发表时间：
1982
期刊：
影响因子：
2.9
通讯作者：
Davis,L
中科院分区：
文献类型：
--
作者：
Matthews,RG;Ross,J;Baugh,CM;Cook,JD;Davis,L
摘要：丝氨酸羟甲基转移酶、甲基四氢叶酸和甘氨酸的三元配合物在502 nm处表现出吸光度，这是由于从甘氨酸的a碳上去除前5质子后形成了奎宁结构。在100µ甘氨酸存在的情况下，测量猪肝丝氨酸羟甲基转移酶与甲基四氢翼酰基聚谷氨酸（CH3-H4PteGlu”）滴定在502 nm处的吸光度变化，以确定与聚谷氨酸侧链残基与酶结合相关的自由能的减少。每个残基的自由能减少约1.0 kcal (4.18 kJ)，这与第二和第三个谷氨酰残基的结合有关。结合第4到第7个谷氨酰残基对每个残基的自由能减少贡献约0.17 kcal （0.73 kJ）。聚谷氨酰侧链的结合能不仅表现为丝氨酸羟甲基转移酶对CH3-H4PteGlu衍生物的亲和力增加，而且表现为酶-CH3-H4PteGlu二元复合物对甘氨酸的亲和力增加。表示了第二和第三个谷氨酰残基的联合结合能
Rowena G. Matthews,** Jonathan Ross, Charles M. Baugh, Janine D. Cook, and Leodis Davis abstract: The ternary complex of serine hydroxymethyl-transferase, methyltetrahydrofolate, and glycine exhibits absorbance at 502 nm, which has been attributed to the formation of a quinoid structure following removal of the pro-5 proton from the a carbon of glycine. Measurements of absorbance changes at 502 nm associated with the titration of pig liver serine hydroxymethyltransferase with methyltetrahydropteroylpolyglutamates (CH3-H4PteGlu „) in the presence of 100 µ glycine have been used to determine the decrease in free energy associated with the binding of the residues of the polyglutamyl side chain to the enzyme. A decrease in free energy of about 1.0 kcal (4.18 kJ) per residue is associated with the binding of the second and third glutamyl residues.Binding of the fourth through seventh glutamyl residues contributes about 0.17 kcal (0.73 kJ) per residue to the de-crease in freeenergy. The binding energy of the polyglutamyl side chain is expressed not only as an increased affinity of serine hydroxymethyltransferase for CH3-H4PteGlu „deriva-tives but also as an increased affinity of the enzyme-CH3-H4PteGlu „binary complex for glycine. The combined binding energy of the second and third glutamyl residues is expressed