HIGH-RESOLUTION H-1-NMR SPECTROSCOPIC STUDIES ON DYNAMIC BIOCHEMICAL PROCESSES IN INCUBATED HUMAN SEMINAL FLUID SAMPLES

High resolution 600MHz H-1 NMR spectroscopy was used to investigate th e changes in biochemical composition of whole human seminal fluid (SF) and an artificial mixture of prostatic (PF) and seminal vesicle fluid (SVF). A variety of time-related biochemical changes were monitored s imultaneously and non-invasively in SF, including enzymatic hydrolysis of phosphorylcholine to choline and polypeptides to amino acids, The fastest NMR-observable reactions in SF were the conversion of phosphor ylcholine to choline (t(1/2) congruent to 9 min) and uridine-5'-monoph osphate (UMP) to uridine (t(1/2) < 2 min). UMP has not previously been detected in SF because of its rapid hydrolysis. Artificial mixtures o f separately obtained prostatic and SVF showed very similar biochemica l changes to those observed in whole SF. Addition of EDTA to SF incuba ted for 2 min post ejaculation strongly inhibited pepride hydrolysis. Zn2+, present in whole SF was shown to be non EDTA-chelatable 2 min af ter ejaculation, whereas after 7 min, a singlet signal from the ethyle nic protons of the Zn-EDTA(2-) complex was clearly observed which rema ined constant after 7 min. This indicates that soon after ejaculation (< 5 min) Zn2+ is immobilised in a macromolecular complex which is rap idly broken down by proteolytic enzymes, the released Zn2+ then being free to react with EDTA. Mg- and Ca-EDTA(2-) complexes were observed a t 2 min and remained constant (at 1.4 and 2.1 mM, respectively) throug hout the entire time course of the experiment, These studies cast new light on the time-related biochemical changes occurring in the post-ej aculatory SF which may have an important role in reproductive function . (C) 1998 Elsevier Science B.V.