title: Prolonged retention of cross-linked trypsin in calcium alginate microspheres.
abstract: Trypsin microencapsulated in a calcium alginate matrix was lost quickly through diffusion when the microspheres were placed in an aqueous medium. This problem was overcome by first reacting trypsin with glutaraldehyde to form cross-linkages and then incorporating the enzyme in the alginate microspheres. The performance of the cross-linked trypsin remained 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-arginine were preferentially hydrolysed by the enzyme indicating that cross-linking did not adversely affect the conformation of the active site. There was a suppression in enzymatic activity when the microspheres were placed in reaction media with an increasing concentration of organic solvent such as ethanol, acetonitrile or isopropanol. However, when returned to a totally aqueous environment, the enzyme resumed its initial tryptic capability. Such a microencapsulated form of cross-linked enzyme may find application in enzyme replacement therapy, optical resolution of racemic compounds as well as organic synthesis in an aqueous-organic environment.
authors.affiliation: Department of Pharmacy, Faculty of Science, National University of Singapore.
authors.forename: W K
authors.initials: WK
authors.lastname: Chui
authors.forename: L S
authors.initials: LS
authors.lastname: Wan
mesh_terms: D000464:Alginates / Q000737:chemistry*; D001586:Benzoylarginine Nitroanilide / Q000737:chemistry; D002863:Chromogenic Compounds / Q000737:chemistry; D003432:Cross-Linking Reagents; D005976:Glutaral / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008863:Microspheres; D013237:Stereoisomerism; D013696:Temperature; D014357:Trypsin / Q000737:chemistry*
chemical_list: D000464:Alginates; D002863:Chromogenic Compounds; D003432:Cross-Linking Reagents; D001586:Benzoylarginine Nitroanilide; D014357:Trypsin; D005976:Glutaral