Transcobalamin II in human seminal plasma.

Abstract

Abstract. Study of cobalamin-binding proteins revealed seminal plasma to be the most concentrated site of transcobalamin II in man. The next richest normal fluid, blood, has approximately one-tenth its concentration. Normal seminal unsaturated cobalamin-binding capacity averaged 15,030±7,290 pg/ml, of which 11,550±6,660 pg/ml was transcobalamin II. Transcobalamin II levels were markedly diminished in subjects lacking seminal vesicles (1520-1660 pg/ml), but not after vasectomy. This suggests that seminal vesicles are the chief source of this protein in semen. R binder concentration was increased in postvasectomy subjects (9,970±4,900 pg/ml vs. 2,980±1,370 pg/ml in normals) and varied in other patients. The endogenous cobalamin content of semen was only 88-699 pg/ml, and was carried largely by R binder rather than by transcobalamin II. The function of the unusually large seminal transcobalamin II pool in reproduction is unknown, but seems unlikely to be related solely to cobalamin transport needs, at least within the male reproductive tract itself.

Prevalence of low serum cobalamin in infertile couples

“…In males for whom there is no known cause for infertility, cobalamin supplementation may easily be overlooked despite its appearance in the medical literature (Sinclair, 2000) to improve sperm counts and motility. Studies have shown that seminal plasma is the most concentrated site of transcobalamin II in man with blood having approximately one-tenth its concentration (Carmel & Bernstein, 1984); whereas this may relate to cobalamin transport needs, the importance to male reproduction needs to be investigated. This study underscores the importance of assessing the male partner of an infertile couple for cobalamin deficiency which is defined as <200 pg ml )1 , although it is clear that lownormal values may be equally predictive of insufficient stores.…”

Monoclonal Antibodies to Different Sites on Human Transcobalamin II

“…Human seminal fluid was obtained from a healthy volunteer (7). Mouse (Balb-C), rabbit (New Zealand White), and guinea pig sera were obtained from animals during previous studies.…”