Overexpression in Escherichia coli and characterization of the chloroplastfructose-1,6-bisphosphatase from wheat

An important Calvin cycle enzyme, chloroplast fructose-1,6-bisphosphatase ( FBPase) from wheat, has been cloned and expressed up to 15% of the total ce ll protein using a pPLc expression vector in Escherichia coli by replacing the codons in the 5'-terminal encoding sequence with optimal and AT-rich on es, The overexpressed wheat FBPase is soluble, fully active, and heat stabl e, It can be purified by chromatography in turn on DEAE-Sepharose and Sepha cryl S-200, and around 15 mg of purified enzymes (>96%) is obtained from 1 liter of cultured bacteria. Its special activity is 8.8 u/mg, K-cat is 22.9 /S, K-m is 121 mu M, and V-max is 128 mu mol/min.mg, The recombinant FBPase can be activated by DTT, Na+, or low concentrations of Li+, Ca2+, Zn2+, Qu HCl, and urea, while it can be inhibited by K+ Or NH4+. (C) 2000 Academic P ress.