Enhancement of enzyme activity and stability by poly(γ-glutamic acid)

Abstract

The effects of poly(γ-glutamic acid) (PGA), a water-soluble poly(amino acid), on the enzyme activity and stability have been investigated. The activity of carbonic anhydrase (CA) was distinctly improved in the presence of 0.30-2.0 γPGA at pH 7. PGA was also effective to enhance the activity of lipase and α-amylase. γPGA efficiently suppressed denaturation of the enzyme by the thermal treatment and repeated freeze-thaw process. The interaction of γPGA and CA was investigated by using fluorescence probe-labeled protein. The Michaelis-Menten kinetics on the CA-catalyzed hydrolysis of p-nitrophenyl acetate in the absence or presence of γPGA were performed, which demonstrated that the enhancement of the CA activity by PGA is ascribed to the increase of the catalytic constant k(cat). © 2010 The Society of Polymer Science, Japan (SPSJ) All rights reserved.