Cold-Induced Volvariella volvacea Cor3 Gene Encodes an S-Adenosyl-L-homocysteine Hydrolase

The full-length cDNA sequence of Volvariella volvacea Cor3 gene was digested with EcoRI restriction enzyme,ligated to the expression vector pPROK-1,and the recombinant plasmid was transformed into Escherichia coli JM109.The encoded protein was over-expressed in the transformed bacteria by addition of 0.5 mmol/L IPTG to the culture medium and cell-free extracts were prepared by sonication.DEAE-cellulose ion-exchange,Sephacryl S-200 gel filtration and QAE-Sepharose negative ion exchange chromatography yielded a single protein band on SDS-PAGE with a molecular mass of 43 kDa and an isoelectric point of 6.1.The purified protein was identified as S-adenosyl-L-homocysteine hydrolase with a synthetic activity(measured by HPLC) of 4.5 μmol/min/mg protein,and a hydrolytic activity(measured by titration of the product homocysteine with 5,5'-dithiobis(2-nitrobenzoic acid) of 0.7 μmol/min/mg.