Abstract
1. 1. An isoenzyme of pea lipoxygenase (linoleate:oxygen oxidoreductase, EC 1.13.1.13) has been purified to essential homogeneity by precipitation with (NH 4) 2SO 4, gel filtration, and ion-exchange chromatography on CM-Sephadex and DEAE-cellulose. The isoenzyme (optimum pH 6.3) bleaches carotene and chlorophyll a in the presence of linoleic acid and O 2. 2. 2. The molecular weight of 78 000 is determined by gel filtration. The amino acid composition was analyzed, and it was shown that the enzyme contains four residues of free sulfhydryl groups and no cystine per molecule. 3. 3. Isoelectric fractionation of the enzyme resulted in two proteins with lipoxygenase and carotene bleaching acitivity; pI values 6.00–6.15. The proteins do not differ in the amino acid composition and in the positional specificity of linoleic acid hydroperoxidation. The raio of the 9- to the 13-hydroperoxy acid was 58:42. 4. 4. The catalytic constant for 1 mole of this pea lipoxygenase (temp.23 °C; pH 6.3): 4600 moles · min −1 linoleic acid and about 1200 moles · min −1 carotene. The rate of chlorophyll degradation is very much lower than the carotene bleaching velocity.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
