碘化作用对肽类激素在双水相聚合物系统中分布的影响。

Effects of iodination on the distribution of peptide hormones in aqueous two-phase polymer systems.

作者信息

Desbuquois B, Aurbach G D

出版信息

Biochem J. 1974 Oct;143(1):83-91. doi: 10.1042/bj1430083.

DOI:10.1042/bj1430083

PMID:4464859

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1168355/

Abstract

The effect of iodination on the distribution of peptide hormones into the aqueous two-phase dextran-polyethylene glycol system and on the solubility of these hormones in aqueous polyethylene glycol and in water was assessed. Hormones that were studied included insulin, glucagon and parathyroid hormone. 2. The partition coefficient of native insulin in the dextran-polyethylene glycol system showed a minimum (about 1) near the isoelectric point of the hormone (pH 5). Partial iodination of insulin (one atom per molecule) caused little change in the distribution of the hormone. More extensive iodination markedly decreased the partition coefficient in the region of the isoelectric point and displaced the pH value at which the partition coefficient was a minimum towards lower values. 3. The solubility of native insulin in aqueous polyethylene glycol and in water showed a pH-dependence similar to that observed for the distribution in the dextran-polyethylene glycol system. Iodination of insulin decreased the solubility of the hormone in polyethylene glycol and in water in parallel, and decreased the pH value at which solubility was a minimum. The changes in solubility correlated with the degree of iodination and accounted for the changes in distribution observed at high concentrations of insulin. 4. Comparable effects of iodination on distribution and solubility were also observed with glucagon. 5. At concentrations of insulin below its maximum solubility, serum proteins caused a decrease in the partition coefficient of iodinated hormone, but not of native hormone. These effects correlated with the degree of iodination and resulted from a co-precipitation of iodinated insulin with serum proteins.

摘要

评估了碘化作用对肽类激素在葡聚糖 - 聚乙二醇水两相系统中的分布以及这些激素在聚乙二醇水溶液和水中溶解度的影响。所研究的激素包括胰岛素、胰高血糖素和甲状旁腺激素。2. 天然胰岛素在葡聚糖 - 聚乙二醇系统中的分配系数在激素的等电点（pH 5）附近显示出最小值（约为1）。胰岛素的部分碘化（每个分子一个碘原子）对激素的分布影响不大。更广泛的碘化显著降低了等电点区域的分配系数，并使分配系数最小的pH值向更低值移动。3. 天然胰岛素在聚乙二醇水溶液和水中的溶解度呈现出与在葡聚糖 - 聚乙二醇系统中分布所观察到的类似的pH依赖性。胰岛素的碘化使激素在聚乙二醇和水中的溶解度平行降低，并降低了溶解度最小的pH值。溶解度的变化与碘化程度相关，并解释了在高浓度胰岛素下观察到的分布变化。4. 对胰高血糖素也观察到了碘化对分布和溶解度的类似影响。5. 在胰岛素浓度低于其最大溶解度时，血清蛋白会导致碘化激素的分配系数降低，但不会使天然激素的分配系数降低。这些影响与碘化程度相关，是由碘化胰岛素与血清蛋白的共沉淀引起的。