Summary: Phosphoribulokinase (ATP:-ribulose-5-phosphate 1-phosphotransferase, EC was purified from the cyanobacterium . The enzyme had a molecular weight of 230000, as determined by gel filtration, and a pH optimum of 8·6. Divalent cations were essential for activity, maximal activity being supported by Mg, while Mn, Ca and Co were less effective. AMP, ADP, phosphoenolpyruvate, aspartate and malate inhibited enzyme activity completely at 1 m. No effects on phosphoribulokinase activity were observed with NAD, NADH, NADP or NADPH at up to 10 mm or with glyoxylate at up to 20 m. The enzyme was activated in semi-purified extracts by the addition of dithiothreitol and reduced glutathione. SDS-PAGE of SDS-dissociated enzyme revealed only one polypeptide band of molecular weight 40000. This suggests that phosphoribulokinase is a hexamer consisting of six subunits of identical size.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error