Effect of addition of water-soluble cationic polymers on thermal stability and activity of glucose dehydrogenase

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).…”

Promotion Effect by ε-Poly-l-lysine on the Enzymatic Reaction of Glucose Oxidase with Ferricyanide Ion as an Oxidant

“…The following is an example that demonstrates the cationic polymer's promotion of an enzyme reaction through the electrostatic interaction. Teramoto et al have reported 8,9 that polyethyleneimine, etc. promote an oxidation reaction of glucose by glucose dehydrogenase with anionic solutes of NAD + and NADP + , considered that the promotion effect can be attributed to an increment of NAD + or NADP + in the vicinity of the enzyme.…”

“…promote an oxidation reaction of glucose by glucose dehydrogenase with anionic solutes of NAD + and NADP + , considered that the promotion effect can be attributed to an increment of NAD + or NADP + in the vicinity of the enzyme. Other causes for the promotion effect by cationic polymers have also been presented, such as a pH shift around the enzyme 8,9 and enzyme structural changes. 10 ε-Poly-L-lysine (ε-PL) has an apparent pKa of 7.6, 11 and the pI of GOD is reported to be around 4.2, 1 so that, in a neutral or acidic solution, ε-PL exists as a cationic polymer and GOD as an anionic colloid.…”

Polyethyleneimine–protein interactions and implications on protein stability

“…Moreover, PEI was reported to be a highly efficient vector for delivering oligonucleotides and plasmids both in vitro and in vivo [9], and since then several efforts have been made to understand and enhance PEI-mediated transfection [10]. It has also been shown to have a stabilizing effect on several enzymes in solution [11][12][13][14] as well as in biosensors [15]. In our earlier studies on the effect of PEI on protein stability, we have demonstrated that PEI 2000 (MW 2000 Da), at a concentration as low as 0.10% (w/v), was highly effective in preventing oxidative damage of porcine muscle lactate dehydrogenase (LDH, EC 1.1.1.27; isoelectric point 8.2) [16].…”