Barkey R J, Shani J, Amit T, Barzilai D
J Endocrinol. 1977 Aug;74(2):163-73. doi: 10.1677/joe.0.0740163.
Ovine prolactin was iodinated by the lactoperoxidase method and purified by gel filtration on Sephadex G-100. The binding ability of the labelled hormone was determined, by incubation with liver homogenate from rabbits in late pregnancy, to be 8-8% total binding/mg protein, of which 86% was specific. The fraction of 125I-labelled ovine prolactin which bound most strongly was subsequently used to study its binding to rat seminal vesicle, prostate and testicular homogenates. The total binding to the seminal vesicle homogenate taken from mature (80-day-old) rats was the highest (11-69%/mg protein), but the greatest degree of binding specificity (82-6%) was to immature (30-day-old) rat prostate. Both total and specific binding to rat testicular homogenate were consistently very low. The binding specificity was demonstrated by displacement studies: while ovine prolactin caused displacement of specific binding, human chorionic gonadotropin, rat thyrotropin and human follicle-stimulating hormone did not cause any significant displacement of bound 125I-labelled ovine prolactin. Affinity constants (Ka) and binding capacities for the seminal vesicle and prostate homogenates were determined by Scatchard analysis and the effect of age on these parameters was studied. There was no difference in Ka between the aged (220-day-old), immature and mature rat tissue homogenates; however, a significant fall in binding capacity was observed in the mature rat prostate, and a further fall in the aged rat prostate. No such change was observed in the binding capacity of the seminal vesicle, as estimated by Scatchard analysis, although total and specific binding to the mature homogenates was higher than that of the other age groups.
采用乳过氧化物酶法对绵羊催乳素进行碘化，并通过葡聚糖凝胶G - 100柱层析进行纯化。通过与妊娠后期兔肝脏匀浆孵育，测定标记激素的结合能力为每毫克蛋白质总结合量的8 - 8%，其中86%为特异性结合。随后，使用结合最强的125I标记绵羊催乳素部分来研究其与大鼠精囊、前列腺和睾丸匀浆的结合。取自成熟（80日龄）大鼠的精囊匀浆的总结合量最高（每毫克蛋白质11 - 69%），但结合特异性最高的是未成熟（30日龄）大鼠前列腺（82 - 6%）。大鼠睾丸匀浆的总结合量和特异性结合量一直都很低。通过竞争置换实验证明了结合特异性：绵羊催乳素可导致特异性结合的置换，而人绒毛膜促性腺激素、大鼠促甲状腺激素和人促卵泡激素不会引起结合的125I标记绵羊催乳素的任何显著置换。通过Scatchard分析确定精囊和前列腺匀浆的亲和常数（Ka）和结合容量，并研究年龄对这些参数的影响。老龄（220日龄）、未成熟和成熟大鼠组织匀浆的Ka没有差异；然而，在成熟大鼠前列腺中观察到结合容量显著下降，老龄大鼠前列腺中进一步下降。通过Scatchard分析估计，精囊的结合容量没有这种变化，尽管与成熟匀浆的总结合量和特异性结合量高于其他年龄组。
