Rasoul Sharifi, Saleh Soleimani, Nazila Amini, Ahmad Panahazari, Samira Sharifi, Seyed Mohammad Atyabi, Meharan Miroliaei,
Volume 4, Issue 14 (4-2014)
Aim and Background: Enzyme action at high salt concentrations is of practical relevance in a number of application areas. Both activity and stability of the horse liver alcohol dehydrogenase correlate well with the Hofmeister series in terms of the salt's kosmotropic/chaotropic properties, which are assessed by the Jones–Dole viscosity B coefficients (B+ for cations and B− for anions). In this study thermal stability and activity of the enzyme were invetigated.
Materials and Methods: In this study, the effects of high concentrations (1- 4 M) of NaCl, NaNO3, Na2SO4 NaClO4, NaAc and concentrations (1-3 M) of KCl, NH4Cl, CsCl on the activity and stability of the horse liver alcohol dehydrogenase enzyme (HLADH) were investigated.
Results: It was found that both enzyme activity and stability of the enzyme are related to the (B−− B+) values of the salts. In the presence of salt whose anions and cations have similar kosmotropic/chaotropic properties (NaAc and NaCl), catalytic activity of enzyme showed the best conditions. kosmotropic/chaotropic properties of both cation and anion affect the catalytic activity of the enzyme by impact on the active site and catalytic mechanism and surface pH. Anions compared with cations had a more predominant role in the stability of the enzyme. Acetate anion may induce greater thermal stability (half-life increased from 300 to 560 min at 60 °C).
Conclusion: The present work has demonstrated explicitly the impact of inorganic salts and ions on both the activity and stability of horse liver alcohol dehydrogenase. The stability study of alcohol dehydrogenase offers another example of more kosmotropic anions and chaotropic cations favoring higher enzyme stability.
