TY - JOUR
T1 - Factors affecting the solubility of Bacillus halmapalus alpha-amylase
AU - Faber, Cornelius
AU - Hobley, Timothy John
AU - Mollerup, Jørgen
AU - Thomas, Owen R. T.
AU - Kaasgaard, S. G.
PY - 2008
Y1 - 2008
N2 - A detailed study of the solubility of recombinant Bacillus halmapalus alpha-amylase has been conducted. A semi-purified preparation from a bulk crystallisation was chos en that contained six isoforms with pI-values of between 5.5 and 6.1. The solubility was strongly affected by pH and could be reduced approximately 200-fold at pH 6 as compared to pH 10, leaving only 0.1 mg/mL in solution. Solubility could also be dramatically manipulated using salts. The choice of anions was found to be more important than of the cations, and the lowest solubility was found using sodium sulphate. For the anions, solubility followed the order expected from the Hofmeister series, however, a more complex behaviour was seen for the cations. With the exception of lithium, their efficiency to influence the solubility was reversed to what was expected. The polydispersity of the solution was reduced by salt addition and zeta potential measurements indicated a shift in pI caused by lithium. Possible explanations for the observations are discussed, extending our present understanding of how salts affect the solubility of proteins, one that to date is primarily based on experiments with lysozyme. (C) 2007 Elsevier B.V. All rights reserved.
AB - A detailed study of the solubility of recombinant Bacillus halmapalus alpha-amylase has been conducted. A semi-purified preparation from a bulk crystallisation was chos en that contained six isoforms with pI-values of between 5.5 and 6.1. The solubility was strongly affected by pH and could be reduced approximately 200-fold at pH 6 as compared to pH 10, leaving only 0.1 mg/mL in solution. Solubility could also be dramatically manipulated using salts. The choice of anions was found to be more important than of the cations, and the lowest solubility was found using sodium sulphate. For the anions, solubility followed the order expected from the Hofmeister series, however, a more complex behaviour was seen for the cations. With the exception of lithium, their efficiency to influence the solubility was reversed to what was expected. The polydispersity of the solution was reduced by salt addition and zeta potential measurements indicated a shift in pI caused by lithium. Possible explanations for the observations are discussed, extending our present understanding of how salts affect the solubility of proteins, one that to date is primarily based on experiments with lysozyme. (C) 2007 Elsevier B.V. All rights reserved.
U2 - 10.1016/j.cep.2007.02.015
DO - 10.1016/j.cep.2007.02.015
M3 - Journal article
VL - 47
SP - 1007
EP - 1017
JO - Chemical Engineering and Processing
JF - Chemical Engineering and Processing
SN - 0255-2701
IS - 6
ER -