RETENTION OF TRYPSIN ACTIVITY IN SPERMINE ALGINATE MICROCAPSULES

We have previously shown virus particles encapsulated in aqueous sperm ine alginate constructs retain immunogenicity and infectivity both in vitro and in vivo. However, because virions are complex structures wit h multiple reinforcing components, it was uncertain if isolated single proteins would retain functional integrity when similarly encapsulate d. To examine this question trypsin, used as a model protein, was blen ded with aqueous sodium alginate and the blend was dispersed as fine d roplets in aqueous spermine hydrochloride to generate self-assembling, trypsin-containing microcapsules. Trypsin was assayed spectrophotomet rically for retention of enzymatic activity using N-alpha-p-tosyl-L-ar ginine methyl ester as substrate. Neither of the encapsulating reagent s alone inhibited enzyme activity. Enzyme that escaped capture was ass ayed directly in the manufacturing supernatant. Tn mass balance studie s we found that about 20-30% of activity was retained in intact capsul es with the remainder resident in the aqueous manufacturing supernatan t and washes. However, we found that the capsule wall appeared to inhi bit enzyme activity by retarding substrate diffusion into and product diffusion out from the capsules, as evidenced by an increase in activi ty on lysis. Thus, it is clear that a single protein, as represented b y trypsin, can retain functional integrity when encapsulated in this a ll aqueous system.