细菌叶绿素
机制(生物学)
化学
光化学
叶绿素
自然(考古学)
生物物理学
环境化学
光合作用
生物化学
生物
有机化学
哲学
古生物学
认识论
作者
Stanley B. Brown,Kevin M. Smith,G. M. F. Bisset,Robert F. Troxler
标识
DOI:10.1016/s0021-9258(19)70607-3
摘要
The photooxidation of methyl pheophorbides, derived from bacteriochlorophyll c, yields ring-opened acetylbilitrienes which are structurally related to mammalian bile pigments. The mechanism of this photooxidation, and that of certain mesomethyl-substituted model compounds, has been studied using 18O labeling with molecular oxygen. In all cases, the methine bridge carbon atoms were retained in the ring-opened photoproducts and both oxygen atoms incorporated into the acetylbilitriene photoproducts were derived from a single oxygen molecule. In this respect, ring opening of bacteriochlorophyll c derivatives and mesomethyl-substituted model compounds differs from the nonphotochemical (enzymatic) ring opening of heme which involves elimination of the methine bridge carbon atom as carbon monoxide and insertion of two oxygen atoms, each from a different molecule of molecular oxygen. The process of photooxidation of bacteriochlorophyll c and mesomethyl-substituted model compounds studied may have implications for the mechanism of natural degradation of chlorophyll a and b during leaf senescence and grain ripening.
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