Binding of Salicylate in the Adenosine‐Binding Pocket of Dehydrogenases

Abstract

Binding of salicylate derivatives to liver alcohol dehydrogenase has been studied by crystallographic and spectrofluorometric methods. We have found that salicylate binds in the hydrophobic adenosine‐binding pocket which has been shown to be structurally similar in all investigated dehydrogenases. The binding of salicylate in this pocket strongly resembles adenosine binding in spite of their very different structures. The position of the phenyl ring partly overlaps the position of adenine; the hydroxyl group of salicylate forms a hydrogen bond to one of the carboxyl oxygen atoms of Asp‐223. This residue has been shown to be invariant in several dehydrogenases. It forms a hydrogen bond to one of the hydroxyls of the adenosine ribose which is important for NAD‐binding. We have also shown that 8‐anilino‐1‐naphthalene sulfonate competes with salicylate for this binding site. A simple fluorometric method based on this competition is proposed for rapid screening of salicylate binding to other enzymes, such as kinases which have coenzyme binding domains similar to those found in dehydrogenases.