Effect of addition of polyethyleneimine on thermal stability and activity of glucose dehydrogenase

Abstract

Abstrzct. When polyethyleneimine (PEI), a water-soluble cationic polymer, was added to solutions of glucose dehydrogenase (GDH) from Bacillus megaterium IWG3 at a molar ratio of PEI to GDH greater than 10, the thermal stability of GDH markedly increased. By addition of PEI, the rate of GDH-catalysed oxidation of flo-glucose increased in a low concentration range of NAD + and NADP + and the Michaelis constants and inhibition constants for both NAD + and NADP + decreased. These results suggested that negatively charged GDH interacts with cationic water-soluble polymers to form conjugates by electrostatic attraction, and also that negatively charged coenzymes are "adsorbed" by the polymers, resulting in enrichment of the coenzymes in the vicinity of GDH. Addition of PEI was also found to be effective for preventing the denaturation of GDH by acrylamide.

Role of a Novel Excipient Poly(Ethylene Glycol)-b-Poly(L-Histidine) in Retention of Physical Stability of Insulin in Aqueous Solutions

“…Polyelectrolyte-enzyme interactions aim at decreasing the denaturation process of a native enzyme, protecting the enzyme from external stresses while at the same time protecting the catalytic activity of the active center. Several investigations have reported that a variety of water-soluble polymers stabilize the enzymatic activities of glucose dehydrogenase, alcohol dehydrogenase, b-galactosidase, and trypsin (32)(33)(34)(35). It has been suggested that electrostatic interactions between the enzymes and the polymers play a dominant role in stabilization of enzyme activities and nonenzymatic proteins (36,37).…”

Photoresist-based integration of enzyme functionality into MEMS

“…Enzyme immobilization was achieved by a 30 min room temperature incubation of small PR samples with 20 ll solution of LOx in phosphate buffered saline (PBS, pH = 7.4) with 25 wt.% poly(ethyleneimine) (PEI) for stabilization of the enzyme on the PR surface (Teramoto et al 1992;Lin et al 1996). The concentration of LOx in PEI/PBS was varied between 0 mg/ml (no LOx) and 10 mg/ml, respectively.…”

Functional Contact Lenses for Remote Health Monitoring in Developing Countries

“…Immobilization of the enzyme on the bare PET surface was achieved by a 30 min room temperature incubation of the sensors with 40 μl 100 U/ml LOx (from Aerococcus viridians, MP Biomedicals, USA) dissolved in PBS with 25 wt.% poly(ethylene)imine for stabilization of the enzyme [24,25].…”