Chrispeels M J
Department of Biology, John Muir College, University of California, San Diego, La Jolla, California 92037.
Plant Physiol. 1970 Feb;45(2):223-7. doi: 10.1104/pp.45.2.223.
The chelator alpha,alpha'-dipyridyl prevents the formation of protein-bound hydroxyproline without affecting protein synthesis as measured by the incorporation of (14)C-proline. The inhibitory effect can be overcome by exogenous ferrous ions. Neither alpha,alpha'-dipyridyl nor Fe(2+) interferes in any other known way with the synthesis and secretion of the hydroxyproline-rich proteins normally found in the cell wall. This reversal by Fe(2+) of the inhibition of proline hydroxylation by alpha,alpha'-dipyridyl is used for a study in vivo of the hydroxylation reaction. This reaction has a temperature coefficient of 2.2, suggesting that it is an enzymatic process. Reversal by Fe(2+) of the alpha,alpha'-dipyridyl inhibition can occur after protein synthesis has been arrested with cycloheximide, indicating that peptidyl proline is the substrate of the hydroxylation reaction. Hydroxylation occurs in the cytoplasm, and not in the cell wall, and only for a limited time after the incorporation of proline into the polypeptide chain. This suggests a spatial separation of the enzyme and the substrate.
螯合剂α,α'-联吡啶可阻止蛋白质结合的羟脯氨酸的形成，而不影响通过（14）C-脯氨酸掺入所测定的蛋白质合成。外源性亚铁离子可克服这种抑制作用。α,α'-联吡啶和Fe(2+)均不会以任何其他已知方式干扰细胞壁中正常存在的富含羟脯氨酸的蛋白质的合成和分泌。Fe(2+)对α,α'-联吡啶抑制脯氨酸羟化的这种逆转作用被用于体内羟化反应的研究。该反应的温度系数为2.2，表明它是一个酶促过程。在用环己酰亚胺阻止蛋白质合成后，Fe(2+)仍可逆转α,α'-联吡啶的抑制作用，这表明肽基脯氨酸是羟化反应的底物。羟化发生在细胞质中，而非细胞壁中，且仅在脯氨酸掺入多肽链后的有限时间内发生。这表明酶和底物在空间上是分离的。
