Fatty acid hydroperoxide lyase (HPO lyase) was purified to apparently homogeneity state from immature fruits of green bell pepper (Capsicum annuum L.) by differential centrifugation, ion-exchange chromatography, hydroxylapatite chromatography and gel filtration. The enzymatic activity was separated into two fractions (HPO lyases I and II) during the chromatography on hydroxylapatite. Both the isoforms were deduced to be trimers of 55-kDa subunits and have similar enzymatic properties. Peptide maps revealed only slight differences between them. Furthermore, immunoblot analysis showed that an antibody raised against HPO lyase I reacted with HPO lyase II as strongly as with the original antigen. These results indicate that there is only limited heterogeneity in terms of amino acid sequence and/or post-translational modification. The activities of both HPO lyases were considerably inhibited by lipophilic antioxidants, such as nordihydroguaiaretic acid and α-tocopherol. The activities with 13-hydroperoxy-(9Z,11E,15Z)-octadecatrienoic acid as substrate were about 12 times higher than those with 13-hydroperoxy-(9Z, 11E)-octadecadienoic acid. By contrast, no reactivity was detectable against the geometrical isomer, 13-hydroperoxy-(9E,11E)-octadecadienoic acid or against the positional isomer, 9-hydroperoxy-(10E,12Z)-octadecadienoic acid. Tissue-print immunoblot analyses using antiserum against HPO lyase indicated that HPO lyase was most abundant in the outer parenchymal cells of the pericarp.
No takes yet. Share an insight, caveat, or question.
A 1995 study studied this question.