Enzymes of purine interconversions in subfractions of lymphocytes

Distribution of enzymes of purine metabolism in lymphocytes of horse, Equus caballus

A microassay requiring as few as 2 X 10(5) cells per assay was developed for systematic analysis of 9 purine enzymes in lymphocytes from equine peripheral blood, spleen, lymph node, thymus and bone marrow. The activities of adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), adenosine kinase (AK), deoxyadenosine kinase (dAK), deoxycytidine kinase (dCK), 5'-nucleotidase (5'-N), AMP deaminase, hypoxanthine-guanine phosphoribosyl transferase (HGPRT or HPRT), and adenine phosphoribosyl transferase (APRT) were measured by this microassay in lymphocytes from peripheral blood from four different breeds of horses (Arabian, Quarter Horse, Thoroughbred and Shetland Pony). There were no significant differences in the enzyme activities among the various breeds. Peripheral blood lymphocytes (PBL) from foals exhibited enzyme activities similar to those observed for adult animals. All lymphoid tissue contained similar levels of activity for each kinase (AK, dAK and dCK). Spleen had the highest activity for ADA, PNP, 5'-N, and HGPRT. The lowest activity for ADA, APRT, PNP and AMP deaminase was found in thymus. Enzymatic activities that varied the most among the tissue were 5'-N, ADA, APRT, HGPRT and AMP deaminase.

Enzymes of purine nucleotide metabolism in human lymphocytes

A methodology is presented for systemic analysis of purine enzymes in small lymphocyte subfractions. For the determination of 7 different enzymes of purine metabolism *hypoxanthine-guanine phosphoribosyltransferase (HG-PRT), adenine phosphoribosyltransferase (A-PRT), adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP), adenosine kinase (AK), 5'-nucleotidase (5'N), and AMP-deaminase) less than 200,000 peripheral blood lymphocytes are needed. 1000-6000 lyophilised lymphocytes are incubated in micro-incubation vessels (3 microliter) with radioactive substrates for 15-180 min. Separation of substrates and products is achieved by thin-layer chromatography on PEI-cellulose. Addition of BSA to the incubation mixtures results in higher specific enzyme activities and narrower ranges of mean values of a control group.