植物过氧化物酶对原卟啉IX的硫醇依赖性降解

Thiol-dependent degradation of protoporphyrin IX by plant peroxidases.

作者信息

Dayan F E, Rimando A M, Duke S O, Jacobs N J

机构信息

USDA/ARS Natural Products Utilization Research Unit, University, MS 38677, USA.

出版信息

FEBS Lett. 1999 Feb 12;444(2-3):227-30. doi: 10.1016/s0014-5793(99)00065-4.

DOI:10.1016/s0014-5793(99)00065-4

PMID:10050764

Abstract

Protoporphyrin IX (PP) is the last porphyrin intermediate in common between heme and chlorophyll biosynthesis. This pigment normally does not accumulate in plants because its highly photodynamic nature makes it toxic. While the steps leading to heme and chlorophylls are well characterized, relatively little is known of the metabolic fate of excess PP in plants. We have discovered that plant peroxidases can rapidly degrade this pigment in the presence of thiol-containing substrates such as glutathione and cysteine. This thiol-dependent degradation of PP by horseradish peroxidase consumes oxygen and is inhibited by ascorbic acid.

摘要

原卟啉IX（PP）是血红素和叶绿素生物合成过程中共同的最后一种卟啉中间体。这种色素通常不会在植物中积累，因为其高度的光动力性质使其具有毒性。虽然通向血红素和叶绿素的步骤已得到充分表征，但对于植物中过量PP的代谢命运却知之甚少。我们发现，在含有谷胱甘肽和半胱氨酸等含硫醇底物的存在下，植物过氧化物酶可以迅速降解这种色素。辣根过氧化物酶对PP的这种硫醇依赖性降解消耗氧气，并受到抗坏血酸的抑制。