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Effects of some factors on protein synthesis in isolated chloroplast

Abstract

The protein synthesis by isolated chloroplasts was light-driven and the saturation light intensity was 450 #mu#mol m~(-2) s~(-1). The rate of protein synthesis was at its maximum in the initial 5 min of illumination and then declined gradually. K~(+) stimulated protein synthesis in isolated chloroplasts, but the stimulation decreased when the concentration of K~(+) was above 30-40 mmol/L. Mg~(2+) stimulated slightly protein synthesis up to a concentration of 1 mmol/L, then the stimulation decreased and obvious inhibition occurred when its concentration was higher than 1.5 mmol/L. The amino acids stimulated effectively protein synthesis in isolated chloroplasts, but stimulation decreased when the concentration of amino acids was above 200 #mu#mol/L. Protein synthesis in isolated chloroplasts was inhibited by DCMU, an inhibitor of noncyclic photophosphorylation, by as much as 41% of the control, indicating the magnitude of the role of noncyclic photophosphorylation in providing ATP for protein synthesis. SDS-PAGE and fluorography showed that the major stromal protein synthesized by isolated chloroplasts was the large subunit of Rubisco, the 32 kD protein in thylakoid membrane was also labeled distinctly.

Key words: Intact chloroplast;Illumination;Protein synthesis

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Citing This Article：

. Effects of some factors on protein synthesis in isolated chloroplast. Acta Physiol Sin 1998; 50 (1): (in Chinese with English abstract).