Evidence for the prostatic origin of gamma-glutamyltranspeptidase activity in human semen

Membrane-associated gamma-glutamyl transferase and alkaline phosphatase in the context of concanavalin A- and wheat germ agglutinin-reactive glycans mark seminal prostasome populations from normozoospermic and oligozoospermic men

Background: Human seminal prostasomes are intrinsically heterogeneous extracellular vesicles (EVs) whose composition is, additionally, influenced by different physiological conditions. Aiming at the molecular properties of the prostasomal surface exemplified by glycan compositions as a possible distinction factor, we applied lectin-affinity chromatography (LAC) as a new tool for their separation. Since glycans, generally, exhibit various biological activities, introduction of glyco-parameters as reference could upgrade standardization of EVs isolated by different methods and intended for use in biomedicine.Methods: Preparations of seminal prostasomes from normozoospermic (sPro-N) and oligozoospermic (sPro-O) men were subjected to LAC on concanavalin A (Con A) and wheat germ agglutinin (WGA) columns. Prostasomes recovered in LAC-separated fractions were characterized according to the distribution of selected markers: gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), tetraspanin CD63, and total protein/glycoprotein composition.Results: Two CD63-immunoreactive populations exhibiting prostasome signature bands but differing in GGT activity and surface glycans were separated on the WGA column. Additional populations having distinct profiles of total glycoproteins and which can be tracked down by ALP activity were enriched on the Con A column. WGA-separated populations were similar in sPro-N and sPro-O, whereas Con A-separated ones were strikingly different.Conclusions: Membrane-associated gamma-glutamyl transferase and alkaline phosphatase in the context of Con A- and WGA-reactive glycans mark seminal prostasomes populations from normozoospermic and oligozoospermic men.

Preliminary investigations on the standardisation and quality control for the determination of ?-glutamyltranspeptidase activity in seminal plasma

The present study was designed to assess the effects of centrifugation velocity, standing time after dilution, freezing-thawing and chymotrypsin on the determination of gamma-glutamyltranspeptidase (gamma-GT) activities in seminal plasma, and to establish an instruction for the standardisation and quality control for the determination of gamma-GT within the same laboratory and among different laboratories. The gamma-GT level and sperm concentration of each of 72 samples of seminal plasma obtained by centrifugation at 1000 g for 10 min or 3000 g for 15 min were assayed. In addition, gamma-GT activities in diluted seminal plasma with different standing time and in samples with or without chymotrypsin were measured. The results showed that there was a significant difference of gamma-GT levels in seminal plasma obtained by centrifugation at different velocities (P < 0.001), and that gamma-GT activities in seminal plasma measured after standing for 30 min after dilution were notably lower than those measured immediately after dilution (P < 0.001). However, the data indicated that both chymotrypsin and freezing-thawing had no apparent effect on the determination of seminal gamma-GT. In conclusion, standing time after dilution and centrifugation velocity should be standardised, and frozen seminal plasma could serve as quality control products for the determination of gamma-GT activity among different laboratories.

Gamma-glutamyltranspeptidase and beta-glucuronidase in human ejaculates. Relation with abnormal liquefaction

Gamma-glutamyltranspeptidase (GGTP) and beta-glucuronidase activity were measured with commercial kits in 104 ejaculates. The two enzyme activities showed a positive correlation and GGTP activity was significantly correlated with sperm number and citrate concentration. GGTP activity is probably from prostatic origin. Ejaculates with abnormal liquefaction had a lower mean GGTP activity compared with ejaculates which showed normal liquefaction. In contrast beta-glucuronidase activity did not show such a difference.

Enzyme levels in semen of men with different types of azoospermia

The levels of eight enzymes have been measured in the semen of 15 azoospermic subjects. The results indicate that the values of the enzymes Creatine kinase, and Alanine aminotransferase, just as the Aspartate aminotransferase/Alanine aminotransferase ratio are significantly different between excretory and secretory azoospermics. The enzymes Aspartate aminotransferase, Lactate dehydrogenase, alpha-Hydroxybutyrate dehydrogenase, Gammaglutamyl transferase, Acid phosphatase, and Alkaline phosphatase and the alpha-Hydroxybutyrate dehydrogenase/Lactate dehydrogenase ratio have values which do not differ significantly between the two groups of azoospermic men.

Prostatic origin of pyruvate kinase activity in human seminal plasma

Pyruvate kinase activity is found in normozoospermic, oligozoospermic, azoospermic and vasectomised human seminal plasma. The split ejaculate technique was used to determine the origin of this enzyme. Sperm number, acid phosphatase activity and fructose concentrations were the control parameters to ensure proper collection. Evidence is presented that the prostate is the major source of pyruvate kinase in human seminal plasma.