title: Rapid degradation of cucumber cotyledon lipoxygenase.
abstract: The lipoxygenase activity from cucumber cotyledons grown with their embryonic axis was separated into two fractions having M(r)s of 90,000 and 96,000, respectively, by hydrophobic chromatography. However, from de-embryonated cucumber cotyledons, only one form of lipoxygenase having a M(r) of 90,000 was purified. The three lipoxygenases could not be distinguished from each other either immunologically or by their enzymatic properties. Furthermore, peptide maps of the 90,000 and 96,000-lipoxygenases were identical. In a crude homogenate of cucumber cotyledons, the 96,000-lipoxygenase was rapidly degraded to the 90,000-form. Thus, it was inferred that the 90,000-lipoxygenase was probably the 96,000-form which had lost a peptide fragment of 6,000. It is suggested that there is a specific proteolytic activity for the degradation of 96,000-lipoxygenase. Estimation of changes in the proteolytic activity during seedling growth suggests that the activity at least partly contributes to the rapid in vivo degradation of cucumber cotyledon lipoxygenase.
authors.affiliation: Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Matsui
authors.forename: M
authors.initials: M
authors.lastname: Irie
authors.forename: T
authors.initials: T
authors.lastname: Kajiwara
authors.forename: T
authors.initials: T
authors.lastname: Kakuno
authors.forename: A
authors.initials: A
authors.lastname: Hatanaka
mesh_terms: D000595:Amino Acid Sequence; D008084:Lipoxygenase / Q000378:metabolism*; D008969:Molecular Sequence Data; D010944:Plants / Q000201:enzymology*; D012639:Seeds / Q000201:enzymology
chemical_list: D008084:Lipoxygenase