Stereospecific ketonization of 2-hydroxymuconate by 4-oxalocrotonate tautomerase and 5-(carboxymethyl)-2-hydroxymuconate isomerase

The stereospecificity of 4-oxalocrotonate tautomerase from Pseudomonas putida mt-2 and 5-(carboxymethyl)-2-hydroxymuconate isomerase from Escherichia coli C was determined. The product, 2-oxo-3-(E)-hexenedioate was trapped and processed to (2-2H1)glutaric acid by chemical degradative procedures. It was found that both enzymes ketonize 2-hydroxymuconate stereospecifically to (S)-2-oxo-3-(E)-(5-2H1)hexenedioate.