Glycerol Carbonate: A Novel Biosolvent with Strong Ionizing and Dissociating Powers

Guangnan Ou,Jianhui Lei,Biyan He,Xuejing Li

doi:10.1100/2012/697161

Abstract

The activity of biocatalysts in nonaqueous solvents is related to the interaction of organic solvents with cells or enzymes. The behavior of proteins is strongly dependent on the protonation state of their ionizable groups, which ionization constants are greatly affected by the solvent. Due to the weak ionizing and dissociating powers of common organic solvents, the charge of the protein will change significantly when the protein is transferred from water to common organic solvents, resulting in protein denaturation. In this work, glycerol carbonate (GC) was synthesized, which ionizing and dissociating abilities were very close to those of water. Transesterification activities of Candida antarctica lipase B (CALB) in GC were comparable to those in water and remained constant during 4-week storage. Bacillus subtilis and Saccharomyecs cerevisiae were cultured in liquid media containing GC with test tubes. In the medium containing low GC concentration, Bacillus subtilis and Saccharomyecs cerevisiae grew well as in a medium containing no organic solvent, but, in the medium containing high GC concentration, the growth of Bacillus subtilis and Saccharomyecs cerevisiae was suppressed. The results suggested that GC is a potential biosolvent, which has great significance to biocatalysis in nonaqueous solvents.

Highlights

The activity of biocatalysts in nonaqueous solvents is related to the interaction of the solvents with cells or enzymes [1,2,3,4]
The results showed that glycerol carbonate (GC) is a good ionizing and dissociating solvent and transesterification activities of Candida antarctica lipase B (CALB) and Candida rugosa lipase (CRL) in GC are similar to those in water
To obtain more information on the reasons for the improvement of enzyme efficiency in GC, we investigated long-term storage stability of CALB in GC and the structurestability relationships of CALB by mass spectrometry

Summary

Introduction

The activity of biocatalysts in nonaqueous solvents is related to the interaction of the solvents with cells or enzymes [1,2,3,4]. In order to take full advantage of the effects of different solvents on enzyme function in designing reaction systems, an understanding of the molecular interactions between solvent and protein is essential. Higher values mean that solvent has higher ability to ionize neutral molecules and to stabilize the formed ions. Two important solvent properties, that is, dielectric constant and donor-acceptor properties, significantly influence both ionization and dissociation processes. We synthesized glycerol carbonate (GC) for the development of soluble enzymatic systems and investigated the effects of various reaction parameters on activity and stability of soluble enzymes. GC has higher ability to ionize neutral ionizable groups of an enzyme and to stabilize the formed ions. The knowledge gained in nonaqueous enzymatic catalysis was applied to the cultivation of microorganisms in nonaqueous media

Materials and Methods

Results and Discussion

Conclusions