CHLOROPHYLL CATABOLISM .6. MECHANISM OF PHOTOOXYGENATION OF THE CD(II) COMPLEX OF PYROPHEOPHORBIDE-A METHYL-ESTER

被引：6

作者：

CURTY, C ^{[1
]}

ENGEL, N ^{[1
]}

ITURRASPE, J ^{[1
]}

GOSSAUER, A ^{[1
]}

机构：

[1] UNIV FRIBOURG, INST ORGAN CHEM, CH-1700 FRIBOURG, SWITZERLAND

来源：

PHOTOCHEMISTRY AND PHOTOBIOLOGY | 1995年 / 61卷 / 06期

关键词：

D O I：

10.1111/j.1751-1097.1995.tb09869.x

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

Photooxygenation of (pyropheophorbidato a methyl ester)cadmium (II) was studied using O-18,18(2) labeling of the molecular oxygen required for cleavage of the macrocycle. After reductive demetallation of the primary oxidation product (4,5-dioxo-4,5-secopyrspheophorbidato a methyl ester)cadmium (II), the isotope content of formylbilinone 4a was analyzed by repeated-scan fast atom bombardment mass spectrometry. Comparison of the spectroscopic data of the labeled pigment 4a with the statistical probabilities of O-18 isotope incorporation calculated for four possible reaction mechanisms clearly proves that photooxidative ring cleavage occurred by the one-molecule mechanism, i.e, the terminal oxygen atoms of 4a were derived from one oxygen molecule. Furthermore, a study of the exchange of the O-18-labeled atoms revealed that no exchange occurs within the pH 4.5-9.5 range. In stronger alkaline or acidic solutions, only the oxygen atom of the formyl group is exchanged, Hydrolysis of the methyl ester group of 4a was achieved, without loss of the O-18 label on the formyl group, at pH 7.2 in the presence of pig liver esterase.

引用

页码：552 / 556

页数：5

共 13 条

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