Identification and characterization of lipoxygenase isoforms in senescing carnation petals.

A membrane-associated lipoxygenase and a soluble lipoxygenase have been identified in carnation (Dianthus caryophyllus L. cv Rêve) petals. Treatments of microsomal membranes by nonionic or zwitterionic detergents indicated that lipoxygenase is tightly bound to the membranes. By phase separation in Triton X-114, microsomal lipoxygenase can be identified in part as an integral membrane protein. Soluble lipoxygenase had an optimum pH range of 4.9 to 5.8, whereas microsomal lipoxygenase exhibited maximum activity at pH 6.1. Both soluble and membrane-associated lipoxygenases produced carbonyl compounds and hydroperoxides simultaneously, in the presence of oxygen. The membranous enzyme was fully inhibited by 0.1 millimolar n-propyl gallate, nordihydroguaiaretic acid, or salicylhydroxamic acid, but the effect of the three inhibitors on the soluble enzyme was much lower. The soluble lipoxygenase is polymorphic and three isoforms greatly differing by their isoelectric points were identified. Lipoxygenase activity in flowers was maximal at the beginning of withering, both in the microsomal and the soluble fractions. Substantial variations in the ratio of the two forms of lipoxygenase were noted at different sampling dates. Our results allowed us to formulate the hypothesis of a strong association of one soluble form with defined membrane constituents.

[1]  J. Thompson,et al.  Characteristics of a membrane-associated lipoxygenase in tomato fruit. , 1990, Plant physiology.

[2]  T. A. Prince,et al.  Floral lipoxygenase: activity during senescence and inhibition by phenidone , 1990 .

[3]  J. Thompson,et al.  Evidence for early changes in membrane structure during post-harvest development of cut carnation (Dianthus caryophyllus L.) flowers. , 1990 .

[4]  T. Eling,et al.  Formation of free radical metabolites in the reaction between soybean lipoxygenase and its inhibitors. An ESR study. , 1989, Biochemistry.

[5]  C. Kemal,et al.  Reductive inactivation of soybean lipoxygenase 1 by catechols: a possible mechanism for regulation of lipoxygenase activity. , 1987, Biochemistry.

[6]  A. Paulin,et al.  Free radical production, catalase and superoxide dismutase activities and membrane integrity during senescence of petals of cut carnations (Dianthus caryophyllus) , 1987 .

[7]  J. Thompson,et al.  Membrane deterioration in senescing carnation flowers : coordinated effects of phospholipid degradation and the action of membranous lipoxygenase. , 1987, Plant physiology.

[8]  John E. Thompson,et al.  Lipoxygenase‐mediated production of superoxide anion in senescing plant tissue , 1984 .

[9]  P. Rustin,et al.  Interaction between Mitochondrial Cytochromes and Linoleic Acid Hydroperoxide: POSSIBLE CONFUSION WITH LIPOXYGENASE AND ALTERNATIVE PATHWAY. , 1982, Plant physiology.

[10]  C. Larsson,et al.  Integral and peripheral proteins of the spinach leaf plasma membrane , 1989 .

[11]  D. Kristie,et al.  Inhibition of lipoxygenase activity: A cautionary note , 1989 .

[12]  John R. L. Walker,et al.  The selective inhibition of catechol oxidases by salicylhydroxamic acid. , 1988 .

[13]  V. Neuhoff,et al.  Improved staining of proteins in polyacrylamide gels including isoelectric focusing gels with clear background at nanogram sensitivity using Coomassie Brilliant Blue G‐250 and R‐250 , 1988, Electrophoresis.

[14]  A. J. Mack,et al.  Lipoxygenase isozymes in higher plants: biochemical properties and physiological role. , 1987, Isozymes.

[15]  E. Dratz,et al.  A new role for phospholipase A2: protection of membranes from lipid peroxidation damage , 1987 .

[16]  B. P. Klein,et al.  Cooxidation reactions of lipoxygenase in plant systems , 1985 .

[17]  R. Legge,et al.  Involvement of hydroperoxides and an ACC-derived free radical in the formation of ethylene , 1983 .

[18]  K. Surrey,et al.  Spectrophotometric Method for Determination of Lipoxidase Activity. , 1964, Plant physiology.