Characterization of heparin low-affinity phospholipase A1 present in brain and testicular tissue.
We identified a unique phospholipase A (PLA) with relatively low heparin affinity, which was distinguishable from the heparin-binding secretory PLA2s, in rat, mouse, and bovine brains and testes. The partially purified enzyme was Ca2+-independent at neutral pH but Ca2+-dependent at alkaline pH. It predominantly hydrolyzed phosphatidic acid (PA) in the presence of Triton X-100 and phosphatidylethanolamine (PE) in its absence. When rat brain-derived endogenous phospholipids were used as a substrate, the enzyme released saturated fatty acids in marked preference to unsaturated ones. Consistent with this observation, the enzyme hydrolyzed sn-1 ester bonds in the substrates about 2,000 times more efficiently than sn-2 ones, thereby acting like PLA1. The enzyme also exhibited weak but significant sn-1 lysophospholipase activity. On the basis of its limited tissue distribution, substrate head group specificity and immunochemical properties, this enzyme appears to be identical to the recently cloned PA-preferring PLA1.
Uchiyama
S
S
Department of Health Chemistry, School of Pharmaceutical Sciences, Showa University, Shinagawa-ku, Tokyo, 142-8555, Japan.
Miyazaki
Y
Y
Amakasu
Y
Y
Kuwata
H
H
Nakatani
Y
Y
Atsumi
G
G
Murakami
M
M
Kudo
I
I
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D006493:Heparin; D006863:Hydrogen-Ion Concentration; D007120:Immunochemistry; D007700:Kinetics; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D010712:Phosphatidic Acids; D010741:Phospholipases A / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D054466:Phospholipases A1; D051381:Rats; D013045:Species Specificity; D013379:Substrate Specificity; D013737:Testis / Q000201:enzymology*; D014018:Tissue Distribution
D010712:Phosphatidic Acids; D006493:Heparin; D010741:Phospholipases A; D054466:Phospholipases A1