title: Transesterification of phosphatidylcholine in sn-1 position through direct use of lipase-producing Rhizopus oryzae cells as whole-cell biocatalyst.
abstract: The enzymatic process presents an advantage of producing specified phospholipids that rarely exist in nature. In this study, we investigated the regiospecific modification of phosphatidylcholine (PC) in the sn-1 position using immobilized Rhizopus oryzae. In a reaction mixture containing egg yolk PC and exogenous lauric acid (LA) in n-hexane, lipase-producing R. oryzae cells immobilized within biomass support particles (BSPs) showed a much higher transesterification activity than lipase powders. To improve the product yield, several parameters including substrate ratio and reaction time were investigated, resulting in the incorporation of 44.2% LA into the product PC after a 48-h reaction. The analysis of the molecular structure showed that a large proportion of exogenous LA (>90%) was incorporated in the sn-1 position of the enzymatically modified PC. Moreover, the BSP-immobilized R. oryzae maintained its activity for more than 12 batch cycles. The presented results, therefore, suggest the applicability of BSP-immobilized R. oryzae as a whole-cell biocatalyst for the regiospecific modification of phospholipids.
authors.affiliation: Bio-energy Corporation, Research and Development Laboratory, 2-9-7 Minaminanamatsu, Amagasaki, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Hama
authors.forename: Kazunori
authors.initials: K
authors.lastname: Miura
authors.forename: Ayumi
authors.initials: A
authors.lastname: Yoshida
authors.forename: Hideo
authors.initials: H
authors.lastname: Noda
authors.forename: Hideki
authors.initials: H
authors.lastname: Fukuda
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
mesh_terms: D001711:Biotransformation; D018914:Cells, Immobilized / Q000378:metabolism; D004951:Esterification; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D008049:Lipase / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D010713:Phosphatidylcholines / Q000737:chemistry* / Q000378:metabolism*; D012233:Rhizopus / Q000201:enzymology* / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D010713:Phosphatidylcholines; D008049:Lipase