Developmental induction, purification, and further characterization of 12:0-ACP thioesterase from immature cotyledons of Umbellularia californica.
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.
Davies
H M
HM
Calgene Inc., Davis, California 95616.
Anderson
L
L
Fan
C
C
Hawkins
D J
DJ
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
D000213:Acyl Carrier Protein; D064429:Fatty Acid Synthases; D013869:Thiolester Hydrolases; C022738:thioesterase II