Bivalent cations stabilize yeast alcohol dehydrogenase I.
The thermostability of yeast alcohol dehydrogenase (ADH) I is strongly dependent on the presence of NaCl, a salt that is almost neutral on the Hofmeister scale, which suggests that solvent-accessible electrostatic repulsion might play a role in the inactivation of the enzyme. Moreover, CaCl2 and MgCl2 are able to stabilize the enzyme at millimolar concentrations. Ca2+ stabilizes yeast ADH I by preventing the dissociation of the reduced form of the enzyme and by preventing the unfolding of the oxidized form of the enzyme. An analysis of several chimaeric ADHs suggests that Ca2+ is fixed by the Asp-236 and Glu-101 side chains in yeast ADH I, but that Ca2+ can be displaced by replacing Met-168 by an Arg residue, as suggested by a three-dimensional model of the enzyme structure. These results indicate that electrostatic repulsion can cause protein unfolding and/or dissociation. It is proposed that yeast ADH I binds Mg2+ in vivo.
De Bolle
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X
Laboratoire de Biologie Moléculaire Structurale, Unité de Recherche en Biologie Moléculaire, Facultés Universitaires Notre-Dame de la Paix, Rue de Bruxelles 61, B-5000 Namur, Belgium.
Vinals
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C
Fastrez
J
J
Feytmans
E
E
D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D000596:Amino Acids / Q000032:analysis; D002122:Calcium Chloride / Q000494:pharmacology; D002413:Cations, Divalent / Q000494:pharmacology*; D004795:Enzyme Stability; D006358:Hot Temperature; D007700:Kinetics; D015636:Magnesium Chloride / Q000494:pharmacology; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae; D012965:Sodium Chloride / Q000494:pharmacology
D000596:Amino Acids; D002413:Cations, Divalent; D015636:Magnesium Chloride; D012965:Sodium Chloride; D000426:Alcohol Dehydrogenase; D002122:Calcium Chloride