Improving Enzyme Activity and Stability Using Polymer Grafting

Improving Enzyme Activity and Stability Using Polymer Grafting

Alvin Sherman Library

Enzymes are ideal chemical catalysts because of their selectivity and specificity. However, the use of enzymes in synthesizing new products is limited by their activity loss due to protein denaturation in a reaction mixture. The purpose of this study is to stabilize model enzymes by attaching them to polymers. Asparaginase, glucose-6-phosphate dehydrogenase and b-galactosidase are chosen for this study. These enzymes are selected because of their important functions in cancer treatment, measuring glucose levels in clinical samples, or making lactose-free dairy products. The free amine groups of N-terminus and lysine residues were chemically modified to attach these enzymes to the polymers carrying primary amine groups. The activity measurements of the free enzyme vs the grafted enzyme was carried out spectrophotometrically and using the mass spectrometry technique. The glucose-6-phosphate dehydrogenase produces reduced NADPH in the presence of glucose-6-phosphate that can be readily measured at 340 nm. The b-galactosidase enzyme converts ONPG into a yellow product that absorbs light strongly at 420 nm. The Asparaginase enzyme changes asparagine into aspartic acid and the reaction activity can be measured using mass spectrometry.