title: Production of 1,2-didocosahexaenoyl phosphatidylcholine by bonito muscle lysophosphatidylcholine/transacylase.
abstract: 1,2-Didocosahexaenoyl phosphatidylcholine (PC), which has highly unsaturated fatty acid at both sn-1 and sn-2 positions of glycerol, is a characteristic molecular species of bonito muscle. To examine the involvement of a de novo route in its synthesis, the molecular species of phosphatidic acid (PA) were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using a 1,3-bis[bis(pyridin-2-ylmethyl)amino]propan-2-olato dizinc(II) complex, a novel phosphate-capture molecule. However, 1,2-didocosahexaenoyl species could not be detected. Next, 1,2-didocosahexaenoyl PC synthesis by the cytosolic lysophosphatidylcholine (LPC)/transacylase was examined using endogenous LPC from bonito muscle, in which the 2-docosahexaenoyl species is abundant. The LPC/transacylase synthesized 1,2-didocosahexaenoyl PC as the most abundant molecular species. For further characterization, the LPC/transacylase was purified to homogeneity from the 100,000 x g supernatant of bonito muscle. The isolated LPC/transacylase is a labile glycoprotein with molecular mass of 52 kDa including a 5-kDa sugar moiety. The LPC/transacylase showed a PC synthesis (transacylase activity) below and above the critical micelle concentration of substrate LPC, and fatty acid release (lysophospholipase activity) was always smaller than the transacylase activity, even with a monomeric substrate. These results suggest that the LPC/transacylase is responsible for the synthesis of 1,2-didocosahexaenoyl PC.
authors.affiliation: Department of Applied Biological Science, Fukuyama University, Fukuyama 729-0292, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Hirano
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Matsui
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Tanaka
authors.forename: Fumito
authors.initials: F
authors.lastname: Matsuura
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Satouchi
authors.forename: Tohru
authors.initials: T
authors.lastname: Koike
mesh_terms: D000217:Acyltransferases / Q000737:chemistry*; D000818:Animals; D002845:Chromatography; D002851:Chromatography, High Pressure Liquid; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005227:Fatty Acids / Q000737:chemistry; D005399:Fishes; D008055:Lipids / Q000737:chemistry; D008244:Lysophosphatidylcholines / Q000737:chemistry*; D008245:Lysophospholipase / Q000737:chemistry*; D008823:Micelles; D008956:Models, Chemical; D009097:Multienzyme Complexes / Q000737:chemistry*; D009132:Muscles / Q000201:enzymology* / Q000378:metabolism; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase / Q000494:pharmacology; D010712:Phosphatidic Acids / Q000737:chemistry / Q000494:pharmacology; D010713:Phosphatidylcholines / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013997:Time Factors; D015032:Zinc / Q000737:chemistry
chemical_list: D005227:Fatty Acids; D008055:Lipids; D008244:Lysophosphatidylcholines; D008823:Micelles; D009097:Multienzyme Complexes; D010712:Phosphatidic Acids; D010713:Phosphatidylcholines; C417741:didocosahexaenoylphosphatidylcholine; D000217:Acyltransferases; D008245:Lysophospholipase; C021782:lysophospholipase-transacylase; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D015032:Zinc