Reminiscence of phospholipase B in Penicillium notatum.
Since the phospholipase B (PLB) was reported as a deacylase of both lecithin and lysolecithin yielding fatty acids and glycerophosphocholine (GPC), there was a question as to whether it is a single enzyme or a mixture of a phospholipase A2 (PLA2) and a lysophospholipase (LPL). We purified the PLB in Penicillium notatum and showed that it catalyzed deacylation of sn-1 and sn-2 fatty acids of 1,2-diacylphospholipids and also sn-1 or sn-2 fatty acids of 1- or 2-monoacylphospholipids (lysophospholipids). Further, it also has a monoacyllipase activity. The purified PLB is a glycoprotein with m.w. of 91,300. The sugar moiety is M9 only and the protein moiety consists of 603 amino acids. PLB, different from PLA2, shows other enzymatic activities, such as transacylase, lipase and acylesterase. PLB activity is influenced by various substances, e.g. detergents, deoxycholate, diethylether, Fe(3+), and endogenous protease. Therefore, PLB might have broader roles than PLA2 in vivo. The database shows an extensive sequence similarity between P. notatum PLB and fungal PLB, cPLA2 and patatin, suggesting a homologous relationship. The catalytic triad of cPLA2, Ser, Asp and Arg, is also present in P. notatum PLB. Other related PLBs, PLB/Lipases are discussed.
Kansai Medical University.
Kunihiko
K
Saito
D000595:Amino Acid Sequence; D000818:Animals; D002241:Carbohydrates / Q000737:chemistry; D020134:Catalytic Domain; D002417:Cattle; D005227:Fatty Acids / Q000737:chemistry; D006023:Glycoproteins / Q000378:metabolism; D006868:Hydrolysis; D007413:Intestinal Mucosa / Q000201:enzymology; D054709:Lecithins / Q000737:chemistry; D008245:Lysophospholipase / Q000378:metabolism*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010179:Pancreas / Q000201:enzymology; D010408:Penicillium chrysogenum / Q000201:enzymology*; D054467:Phospholipases A2 / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000201:enzymology; D013379:Substrate Specificity
D002241:Carbohydrates; D005227:Fatty Acids; D006023:Glycoproteins; D054709:Lecithins; D054467:Phospholipases A2; D008245:Lysophospholipase