Structure-function relationships in 3-phosphoglycerate kinase: role of the carboxy-terminal peptide.
Structure-function relationships in 3-phosphoglycerate kinase: role of the carboxy-terminal peptide.
复制标题
3-磷酸甘油酸激酶的结构-功能关系：羧基末端肽的作用。
DOI：
10.1002/prot.340040108
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发表时间：
1988
期刊：
影响因子：
2.9
通讯作者：
Resplandor,ZE
中科院分区：
文献类型：
--
作者：
Mas,MT;Resplandor,ZE
Yeast 3‐phosphoglycerate kinase (PGK) is a monomeric enzyme (Mr∼ 45,000) composed of two globular domains. Each domain corresponds approximately to the amino‐ and carboxyterminal halves of the polypeptide chain. The carboxy‐terminal end extends over the interdomain “hinge” region and packs against the amino‐terminal domain. It has been proposed that domain movement, resulting in closure of the active site left, is essential for the catalytic of PGK. Large‐scale conformational changes have also been postulated to explain activation of the enzyme by sulfate ions. Using site‐specific mutagenesis, we have removed a 15‐amino‐acid carboxy‐terminal fragment, in order to probe its role in the substrate‐ and sulfate‐induced conformational changes. The truncated enzyme exhibited approximately 1% of the activity of native PGK and lost the ability to undergo sulfateinduced activation. The Kmfor ATP was essentially unchanged (Km= 0.23mM), whereas the Kmvalue for 3‐phosphoglycerate was increased about eightfold (Km= 3.85 mM and 0.50 mM, respectively). These results suggest that the carboxy‐terminal segment is important for the mechanism of substrate‐ and specific‐induced conformational transitions. CD spectra and sedimentation velocity measurements indicate that the carboxy‐terminal peptide is essential for structural integrity of PGK. The increased susceptibility of the truncated enzyme to thermal inactivation implies that the carboxy‐terminal peptide also contributes to the stability of PGK.
