AMINE COMPOSITION INFLUENCES APPARENT ACTIVITY OF ENZYME IN CHARGED FILM MICROCAPSULES

It has been shown that, when captured in charged film microcapsules pr epared from spermine alginate, intact viruses retain infectivity, isol ated viral proteins retain immunogenicity, and trypsin retains enzymat ic activity. However, it was unclear whether the greater anionic stren gth of hemisulfate residues such as those in carrageenan might alter p rotein conformation and activity unfavourably in comparison with the l esser influence of alginate carboxylates. Further, the influence of th e structure of the amine used to prepare the capsules was largely unkn own. To examine these questions, trypsin, used as a model protein, was ; encased in microcapsules prepared from iota-carrageenan and oligoami nes drawn from either the homologous series spermine, spermidine, putr escine or ethylenediamine, diethylenetriamine, triethylenetetramine, t etraethylenepentamine. The gross structures of encapsulated and native trypsin were compared by denaturing electrophoresis and their enzymat ic activity by the method of Hummel. In all encapsulations SDS PAGE ga ve no evidence of alteration of protein structure. When encapsulated, the apparent activity of trypsin was reduced by about 60 to 75%, but w hen the capsules were lysed in hypertonic saline activity was restored . This apparent reduction in activity is attributed to the diffusional barrier imposed by the encapsulating membrane but it should be recogn ized that it may be the result of reversible denaturation.