Effect of salts on the solubility of thermolysin: a remarkable increase in the solubility as well as the activity by the addition of salts without aggregation or dispersion of thermolysin.

Publisher Website
Google Scholar
Abstract
Thermolysin is remarkably activated in the presence of high concentrations (1–5 M) of neutral salts [Inouye, K. (1992) J. Biochem. 112, 335–340]. The activity is enhanced 13–15 times with 4 M NaCl at pH 7.0 and 25°C. In this study, the effect of neutral salts on the solubility of thermolysin has been examined. Although the solubility was only 1.0–1.2 mg/ ml in 40 mM Tris-HCl buffer, pH 7.5, in the temperature range between 0 and 60°C, it was increased greatly by the addition of salts. With NaCl, the solubility showed a bell-shaped behavior with increasing NaCl concentration, and the maximum solubility (10 mg/ml) was at 2.0–2.5 M NaCl. With LiCl and Nal, it increased progressively to 20–50 mg/ml with increasing salt concentration up to 5 M. The solubility observed in the presence of salts decreased with increasing temperature from 0 to 60°C, and also with the order of chaotropic anion effect. The molecular weight of thermolysin was estimated to be 33.0(±2.5) × 103 in the presence of 0–3 M NaCl, suggesting that thermolysin exists as a monomer in the presence or absence of 3 M NaCl. The possibility that aggregation and/or dispersion of thermolysin might be related to the remarkable activation by salt was ruled out.

This publication has 0 references indexed in Scilit: