Relative affinity of 5,10-methylenetetrahydrofolylpolyglutamates for the Lactobacillus casei thymidylate synthetase-5-fluorodeoxyuridylate binary complex.
Relative affinity of 5,10-methylenetetrahydrofolylpolyglutamates for the Lactobacillus casei thymidylate synthetase-5-fluorodeoxyuridylate binary complex.
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5,10-亚甲基四氢叶酰基聚谷氨酸盐对干酪乳杆菌胸苷酸合成酶-5-氟脱氧尿苷酸二元复合物的相对亲和力。
DOI：
10.1016/0003-9861(81)90171-5
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发表时间：
1981
影响因子：
3.9
通讯作者：
Mangum,M
中科院分区：
文献类型：
--
作者：
Priest,DG;Mangum,M
用动力学和平衡技术研究了一系列亚甲基四氢叶酸多谷氨酸盐对干酪乳杆菌与氟脱氧尿苷酸合成酶二元配合物的亲和力。在0°C下测定了多谷氨酸与1 ~ 7个谷氨酸残基的相对结合率。用十二烷基硫酸钠淬火停止反应，随后用凝胶过滤色谱法测定结合的氚化氟脱氧尿苷酸。速率增加到5个残基，超过5个残基就会略有下降。从同一系列中所有可能的多谷氨酸对的相对平衡结合亲和力是通过氚化配合物的电泳分离来确定的。在每一种情况下，长链的成员对结合更紧密。将仅包含胸腺苷酸合成酶单个亚基的复合物与两个亚基结合的复合物进行了比较。与二聚体（2:2:1）相比，单聚体（1:1:1）的配合物对链长较长的分子具有更大的亲和力。这些结果可以用胸苷酸合成酶的可能结合位点模型来解释。
The affinity of a series of methylenetetrahydrofolate polyglutamates for the binary complex ofLactobacillus caseithymidylate synthetase and fluorodeoxyuridylate has been investigated by kinetic and equilibrium techniques. The relative rates of binding for polyglutamates with one through seven glutamate residues were determined at 0 °C. Reactions were stopped by quenching into sodium dodecyl sulfate with subsequent determination of bound tritiated fluorodeoxyuridylate by gel filtration chromatography. Rates increased up to five residues beyond which a slight decrease occurred. Relative equilibrium binding affinities for all possible pairs of polyglutamates from the same series were determined by electrophoretic separation of tritiated complexes. In every case, the longer chain length member of the pair was bound more tightly. Complexes involving only a single subunit of thymidylate synthetase were compared with those in which both subunits were bound. Monomeric (1:1:1) complexes invariably showed a greater affinity for the longer chain length member of the pair than the corresponding dimeric (2:2:1) species. These results are interpreted in terms of possible binding site models for thymidylate synthetase.