PROLONGED RETENTION OF CROSS-LINKED TRYPSIN IN CALCIUM ALGINATE MICROSPHERES

Trypsin microencapsulated in a calcium alginate matrix was lost quickl y through diffusion when the microspheres were placed in an aqueous me dium. This problem was overcome by first reacting trypsin with glutara ldehyde to form cross-linkages and then incorporating the enzyme in th e alginate microspheres. The performance of the cross-linked trypsin r emained optimal at pH 8 while it was found to be more heat-stable and remained highly active even at 80 degrees C. Esters and amides of L-ar ginine were preferentially hydrolysed by the enzyme indicating that cr oss-linking did not adversely affect the conformation of the active si te. There was a suppression in enzymatic activity when the microsphere s were placed in reaction media with an increasing concentration of or ganic solvent such as ethanol, acetonitrile or isopropanol. However, w hen returned to a totally aqueous environment, the enzyme resumed its initial tryptic capability. Such a microencapsulated form of cross-lin ked enzyme may find application in enzyme replacement therapy, optical resolution of racemic compounds as well as organic synthesis in an aq ueous-organic environment.