title: Separation of phospholipase A2 in the testis and cauda epididymis of the adult rat by chromatofocusing.
abstract: Phospholipase A2 (PLA2) activity was measured in the reproductive organs of adult male rats. Phosphatidylethanolamine and phosphatidylcholine labelled with 14C linoleic (lino-PE, lino-PC) and arachidonic acid (ara-PE, ara-PC) at the 2-position were used as substrates. Lino-PE was hydrolysed most strongly by homogenates of the distal cauda epididymis but the testis, vas deferens and caput and corpus epididymis also contained hydrolytic activity. Ara-PC and lino-PC were hydrolysed by homogenates of the cauda epididymis and testis. No hydrolysis of ara-PE was detected using homogenates of reproductive tissues. Chromatofocusing of testis homogenate resulted in the appearance of two active forms of PLA2 with different pl-values (6.5 and 5.6) when lino-PE was used as substrate. Maximum activities of both enzymes with 1 mM Ca2+ were observed at pH 9.5. These isoenzymes have marked differences in response to Cu2+, N-ethylmaleimide and p-bromophenacyl bromide (p-BPB). Cu2+ and N-ethylmaleimide had almost no effect on PLA2 activity with a pl value of 6.5, but inhibited the other isoenzyme strongly; the latter was almost more resistant to p-bromophenacyl bromide. Both enzymes hydrolysed lino-PE most strongly. Chromatofocusing of an homogenate of cauda epididymis also revealed two isoenzymes of PLA2 with different pl-values (6.0 and 5.0). The latter form was resistant to p-bromophenacyl bromide but was more sensitive to Triton X-100 and sodium deoxycholate than was other isoenzyme. The pH optimum of the isoenzyme with a pl value of 6.0 ranged from 6.25 to 8.75 whilst the other isoenzyme was most active at pH 8.0-8.75.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Anatomy, University of Kuopio, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Rönkkö
mesh_terms: D000818:Animals; D002845:Chromatography; D004822:Epididymis / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D008066:Lipolysis; D008297:Male; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D051381:Rats; D011919:Rats, Inbred Strains; D013737:Testis / Q000201:enzymology / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D010741:Phospholipases A; D054467:Phospholipases A2