Photoreductive path of carbon fixation in green plant photosynthesis. Reaction pathway of six-carbon ribulose 1,5-bisphosphate carboxylation adduct intermediate

Fong, Francis K.; Butcher, Karen

doi:10.1016/0006-291x(87)91475-6

Cited by 4 publications

(1 citation statement)

References 25 publications

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“…They also found that CA1P degradation was sensitive to the uncoupler nigericin, but not to the same degree that light-induced changes in Rubisco carbamylation were, and concluded that CA1P and Rubisco activase regulation of Rubisco are functionally different. Fong and Butcher (1987) have suggested that enzyme-bound NADP may function together with CA1P as modulators of light-dependent Rubisco activity. Seemann et al (1985) demonstrated that alkaline phosphatase was capable of degrading CA1P bound to carbamylated Rubisco in vitro, thereby restoring enzyme activity.…”

Section: Biochemical Aspects Of Ca1p Degradationmentioning

confidence: 99%

Metabolism of 2-carboxyarabinitol 1-phosphate and regulation of ribulose-1,5-bisphosphate carboxylase activity

1990

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Metabolism of 2'-carboxy-D-arabinitol 1-phosphate (CA1P) is an important component in the light-dependent regulation of ribulose-1,5-bisphosphate carboxylase (Rubisco) activity and whole leaf photosynthetic CO2 assimilation in many species, and functions as one mechanism for regulating Rubisco activity when photosynthesis is light-limited. Species differ in their capacity to accumulate CA1P, ranging from those which can synthesize levels of this compound approaching or in excess of the Rubisco catalytic site concentration, to those which apparently lack the capacity for CA1P synthesis. CA1P is structurally related to the six carbon transition state intermediate of the carboxylation reaction and binds tightly to the carbamylated catalytic site of Rubisco, making that site unavailable for catalysis. Under steady-state, the concentration of CA1P in the leaf is highest at low photon flux density (PFD) or in the dark. Degradation of CA1P and recovery of Rubisco activity requires light and is stimulated by increasing PFD. The initial degradation reaction is catalyzed by an enzyme located in the chloroplast stroma, CA1P phosphatase, which yields carboxyarabinitol (CA) and inorganic phosphate as its products. The pathway of CA metabolism in the plant remains to be determined. Synthesis of CA1P occurs in the dark, and in Phaseolus vulgaris this process has been shown to be stimulated by low PFD. The pathway of CA1P synthesis and its relationship to the degradative pathway remains unknown at the present time. The discovery of the existence of this previously unknown carbon pathway in photosynthesis indicates that we still have much to learn concerning the regulation of Rubisco activity and photosynthesis.

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Section: Biochemical Aspects Of Ca1p Degradationmentioning

confidence: 99%