Resonance Raman investigation of an enzyme-inhibitor complex.

The resonance Raman spectrum has been recorded for two different binary complexes formed between 2-carboxy-2'-hydroxy-5'-sulfoformazylbenzene (zincon) and liver alcohol dehydrogenase. The shifts in the zincon spectrum upon complexation with enzyme in one complex are similar to those in model compounds containing azo or formazyl linkages upon complexation of these with zinc. The results are interpreted in terms of complexation of zincon to a zinc atom at the enzyme active site. Since zincon is a coenzyme competitive inhibitor, it is probably bound at or near the coenzyme binding site; the results of this study, therefore, are useful in understanding the chemistry of zinc at the enzyme active site.