Multipoint Immobilization of Invertase on Agarose: Stability and Kinetic Properties

Enzyme immobilization is a specific method for restricting the enzyme freedom of movement. There are strategies for the proteins multipoint immobilization by amine-terminal residues, lysine residues and carboxylic groups. In the present work, a commercial invertase of Saccharomyces cerevisiae underwent multipoint immobilization on glyoxyl-agarose, amine-agarose and glutaraldehyde-agarose supports. Derivatives kinetic properties were determined and compared with the properties of the soluble enzyme. The copper influence on enzyme activity and its inhibition by fructose were also investigated. Amine-agarose exhibited activity closest to the soluble enzyme (93.3%). This same derivative maintained approximately 50% of initial activity when 800mM of fructose were added to the reaction medium. However, glutaraldehyde-agarose exhibited the best stability to temperature and pH and none of the derivatives lost inhibition by copper. Glyoxyl derivative exhibited the lowest Km (0.023mM) and amine derivative achieved the highest maximum velocity (1666.7 U/mg prot.).