Hölpert M, Cooper T G
Max Planck Clinical Research Unit for Reproductive Medicine, Münster, Federal Republic of Germany.
J Reprod Fertil. 1990 Nov;90(2):503-14. doi: 10.1530/jrf.0.0900503.
Using an assay for alpha-lactalbumin in which galactosyltransferase activity was stabilized and a tissue phosphatase inhibitor was present, no evidence was found for alpha-lactalbumin-like activity in rat epididymal tissue, epididymal fluids or medium from cultured epididymal epithelial cells with either glucose or N-acetylglucosamine as acceptor. However, when assay conditions were suboptimal, apparent transfer of radioactivity to both acceptors could be demonstrated in the epididymis and other tissues. In these assays the amount of alpha-lactalbumin registered was linearly correlated to the extent of stimulation of alpha-lactalbumin added exogenously to tissue extracts as internal standards. When rete testis fluid from rats was used as source of galactosyltransferase under suboptimal conditions, no transfer to glucose was demonstrable in epididymal fluid and an apparent decreased transfer to N-acetylglucosamine could be explained by increases in (pyro)phosphatase activity. Putative alpha-lactalbumin activity in the epididymis may be an artefact of unoptimized assays.
在一种用于检测α-乳白蛋白的实验中，半乳糖基转移酶活性得以稳定，且存在一种组织磷酸酶抑制剂。在以葡萄糖或N-乙酰葡糖胺作为受体的情况下，未在大鼠附睾组织、附睾液或培养的附睾上皮细胞培养基中发现α-乳白蛋白样活性的证据。然而，当实验条件欠佳时，在附睾及其他组织中可证实放射性明显转移至两种受体。在这些实验中，所记录的α-乳白蛋白量与作为内标添加到组织提取物中的外源性α-乳白蛋白的刺激程度呈线性相关。当在欠佳条件下使用大鼠睾丸网液作为半乳糖基转移酶的来源时，在附睾液中未证实向葡萄糖的转移，而向N-乙酰葡糖胺的明显转移减少可通过（焦）磷酸酶活性的增加来解释。附睾中假定的α-乳白蛋白活性可能是未优化实验的假象。
