title: Developmental induction, purification, and further characterization of 12:0-ACP thioesterase from immature cotyledons of Umbellularia californica.
abstract: The fatty acyl content of developing cotyledons of Umbellularia californica (California Bay) changes from a long-chain composition to a predominance of 10:0 and 12:0 in just 4-5 days at the beginning of an approximately 100-day period of medium-chain deposition. This striking change occurs at the earliest appearance of 12:0-acyl-carrier protein (ACP) thioesterase activity. The coincidence of these rapid events is consistent with the hypothesis that the enzyme plays a major role in medium-chain biosynthesis. The 12:0-ACP thioesterase has been substantially purified; enzyme activity consistently comigrates in chromatographic and electrophoretic systems with a protein or pair of proteins having an apparent molecular weight of approximately 34 kDa. A native molecular weight of approximately 42 kDa has been estimated by gel filtration chromatography, suggesting that the enzyme is a monomer. Affinity chromatography on immobilized ACP is a critical step in the purification procedure, and resolves the 12:0-ACP and 18:1-ACP thioesterases sufficiently to confirm that the medium-chain enzyme has negligible action on 18:1-ACP.
authors.affiliation: Calgene Inc., Davis, California 95616.
authors.forename: H M
authors.initials: HM
authors.lastname: Davies
authors.forename: L
authors.initials: L
authors.lastname: Anderson
authors.forename: C
authors.initials: C
authors.lastname: Fan
authors.forename: D J
authors.initials: DJ
authors.lastname: Hawkins
mesh_terms: D000213:Acyl Carrier Protein; D002846:Chromatography, Affinity; D004790:Enzyme Induction; D064429:Fatty Acid Synthases / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D008970:Molecular Weight; D012639:Seeds / Q000201:enzymology* / Q000254:growth & development; D013379:Substrate Specificity; D013869:Thiolester Hydrolases / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D000213:Acyl Carrier Protein; D064429:Fatty Acid Synthases; D013869:Thiolester Hydrolases; C022738:thioesterase II