Overexpression, purification, and some properties of the AdoCbl-dependent ethanolamine ammonia-lyase from Salmonella typhimurium.

Recombinant ethanolamine ammonia-lyase from S. typhimurium has been overexpressed and purified in large quantities by a simple procedure. The molecular weight of the native enzyme is about 480 kDa, and it contains two active sites/molecule as shown by kinetic studies and by titration with CNCbl. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis confirms earlier cloning studies indicating that it is composed of two kinds of subunits, one of MW 31 kDa and the other of MW 50 kDa. These subunits, inactive by themselves, combine to produce an active enzyme whose composition is most likely alpha 6 beta 6. The Km for AdoCbl is 0.5 microM, and the turnover number is 55 s-1 per active site at 22 degrees C.