1 Diagram (simplified) of
the reactions of photorespiration, involving chloroplast, peroxisome and mitochondrion.
The process begins with the wasteful oxidative reaction of rubisco in the chloroplast
stroma, producing glycolate, which enters peroxisomes by a special porin protein
channel in their membrane. Its conversion to glyoxylate releases hydrogen peroxide
(broken down by catalase). Transamination to glycine, subsequent conversions
in mitochondria, and return to peroxisomes and thence to chloroplasts allows
some of the original carbon to conserved by its re-entry into the photosynthetic
carbon reduction cycle.
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