CO2 evolution in peroxisomes isolated from spinach leaves at various ages
1988
Lee, S.H. | Park, K.Y. (Yonsei Univ., Seoul (Korea R.). Dept. of Biology) | Lee, I.C. (Taejon Univ., Taejon (Korea R.). Dept. of Biology) | Yamada, Yoshio (Kuyshu Univ., Fukuoka (Japan). Laboratory of Plant Nutrition)
The rates of photorespiration and total CO2 fixation depending on leaf ages of spinach (Spinacia oleracea L.) were investigated. Metabolic rates of glycolate and glyoxylate in isolated peroxisomes were also measured. The rate of photorespiration and total CO2 fixation ability increased with the maturing of leaf, but decreased with senescence. Activities of enzymes involved in the peroxisomal photorespiratory pathway such as catalase, glycolate oxidase, NADH-glyoxylate reductase and glutamate-glyoxylate transaminase were highest in the mature leaf, but also decreased with aging of leaf. Glutamate-glyoxylate transaminase activity significantly decreased with senescence, especially. The metabolic rate of glycolate was observed to be lower than that of glyoxylate in isolated peroxisomes. Glycolate seemed to be metabolized mainly to glycine however, it also oxidized to CO2 when glycolate was supplied as a substrate for glycine synthesis instead of glyoxylate. The conversion rates of glycolate and glyoxylate into CO2 increased with the senescence of leaves
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