Reversible immobilization of glycoamylase by a variety of Cu2+‐chelated membranes

Glycoamylase (AMG) is an γ‐amylase enzyme which catalyzes the breakdown of large α(1,4)‐linked malto‐oligosaccharides to glucose. It is an extracellular enzyme and is excreted to the culture medium. In this study, AMG was immobilized on a variety of metal affinity membranes, which were prepared by chelating Cu²⁺ ions onto poly(hydroxyethyl methacrylate) (PHEMA) using N‐methacryloyl‐(L )‐histidine methyl ester (MAH), N‐methacryloyl‐(L )‐cysteine methyl ester (MAC), and N‐methacryloyl‐(L )‐phenylalanine methyl ester (MAPA) as metal‐chelating comonomers for reversible immobilization of AMG. The PHEMAH, PHEMAC, PHEMAPA membranes were synthesized by UV‐initiated photo‐polymerization and Cu²⁺ ions were chelated on the membrane surfaces. Cu²⁺‐chelated membranes were characterized by swelling tests, SEM, contact angle measurements, elemental analysis, and FTIR. AMG immobilization on the Cu²⁺‐chelated membranes was performed by using aqueous solutions of different amounts of AMG at different pH values and Cu²⁺ loadings. Durability tests concerning desorption of AMG and reusability of the Cu²⁺‐chelated membranes yielded acceptable results. It was computationally determined that AMG possesses four likely Cu²⁺/Zn²⁺ binding sites, away from the catalytic site, to which the metal‐chelated membranes can be efficiently used. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012