4.1.3.39 2-ketobutanoate - 3288 4.1.3.39 2-ketopentanoate - 3158 4.1.3.39 4-methyl-2-oxopentanoate - 722 4.1.3.39 glyoxylate - 101 4.1.3.39 pyruvate - 31 4.1.3.39 Zn2+ strong inhibition 14