Department of Horticulture, University of Illinois, Urbana, Illinois 61801.
Plant Physiol. 1979 Feb;63(2):227-31. doi: 10.1104/pp.63.2.227.
The intraplastidic localization of the endogenous metabolic pools from protoporphyrin to protochlorophyll was determined in Cucumis sativus. The endogenous protoporphyrin, Mg-protoporphyrin monoester + longer wavelength metalloporphyrins, protochlorophyllide and protochlorophyllide ester were membrane-bound. Protoporphyrin was synthesized in the stroma and subsequently became associated with the membranes. The membrane-associated protoporphyrin was then converted into Mg-protoporphyrin monoester + longer wavelength metalloporphyrins by membrane-bound enzymes. Although lysed plastids were capable of converting exogenous delta-aminolevulinic acid to protochlorophyllide, the net synthesis of protochlorophyllide from exogenous delta-aminolevulinic acid was lost upon segregating the lysed plastids into stromal and membrane fractions and then recombining the stromal and membrane fraction prior to incubation. The segregated membrane fraction was still capable of converting protoporphyrin into Mg-protoporphyrin monoester + longer wavelength metalloporphyrins in the presence or absence of the stromal fraction. These results indicated that although the reactions from protoporphyrin to Mg-protoporphyrin monoester and longer wavelength metalloporphyrins could survive a considerable degree of plastid disruption, the reactions from Mg-protoporphyrin monoester and longer wavelength metalloporphyrins to protochlorophyllide were more sensitive to structural disorganization.
在黄瓜中确定了内源代谢池从原卟啉到原叶绿素的质体内部定位。内源原卟啉、Mg-原卟啉单酯+长波金属卟啉、原叶绿素ide 和原叶绿素ide 酯是膜结合的。原卟啉在基质中合成，然后与膜结合。膜结合的原卟啉随后被膜结合酶转化为 Mg-原卟啉单酯+长波金属卟啉。尽管裂解的质体能够将外源 δ-氨基乙酰丙酸转化为原叶绿素ide，但将裂解的质体分离成基质和膜部分，然后在孵育前重组基质和膜部分后，外源 δ-氨基乙酰丙酸的原叶绿素ide 的净合成就丢失了。分离的膜部分仍然能够在存在或不存在基质部分的情况下将原卟啉转化为 Mg-原卟啉单酯+长波金属卟啉。这些结果表明，尽管从原卟啉到 Mg-原卟啉单酯和长波金属卟啉的反应可以在相当大程度的质体破坏下存活，但从 Mg-原卟啉单酯和长波金属卟啉到原叶绿素ide 的反应对结构去组织化更为敏感。
