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Model for Inactivation of α‐Amylase in the Presence of Salts: Theoretical and Experimental Studies
Author(s) -
Lecker Douglas N.,
Khan Arshad
Publication year - 1998
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp980024y
Subject(s) - chemistry , dissociation (chemistry) , salt (chemistry) , ion , ammonium , enzyme , aqueous solution , potassium , inorganic chemistry , sodium , sodium citrate , amylase , biochemistry , organic chemistry , medicine , pathology
According to a previous report, only the smaller anions, like chlorides, that readily fit into the anion binding site of α‐amylase can cause an increased stability (relative to enzymes in aqueous solution), and the anions that are too large to fit into the binding site should have no effect on the enzyme. Even though the results on large benzoate ions are consistent with the above postulate, much larger citrate ions from sodium and potassium citrate show stabilization at moderate salt concentrations and follow an expected trend of low stability only at large salt concentrations. The citrate ions from ammonium citrate exhibit very little to almost no stabilization. In addition, low to moderate concentrations of NaCl that provide a large stability to the enzyme show almost no stability in the presence of EDTA. We put forward an inactivation model that involves a reversible dissociation of the anion bound to the protein, followed by a reversible inactivation step of calcium ion dissociation and an irreversible denaturation step of apoenzyme.