24-12

R. BRIONES-MARTíNEZ¹, O. Menéndez, A. R. López, and M. I. CORTéS-VáZQUEZ. (1) Biotecnología/Enzimología, Centro de Desarrollo de Productos Bióticos, COFAA, Instituto Politécnico Nacional, Km 8 Carr. Yautepec-Jojutla, Yautepec, Morelos, 62730, Mexico

JUSTIFICATION: Chom (Maya name for Bromelia karatas) is a plant from the south-east of México. Our research group reported in previous work the isolation of a new proteinase from chom fruit´s juice. The enzyme, karatasin, is a cysteinic proteinase formed by eight multiple molecular forms, with a wide spectra of isolelectric points (from 3.4-10.4). As other Bromeliaceae proteases, like bromelain, karatasin could have a potential as a biocatalyst in food proteins modification. Until now this proteinase has been obtained only from the fruit juice. But now we are interested in evaluating the enzyme content remaining in the peel part in order to increase the yield of enzyme.

OBJECTIVE: Our objective was to evaluate comparatively the yield and activity of karatasin isolated from fruit juice and from its wastes (peel part).

METHODS: Chom fruits were collected in our experimental plantation at Campeche, México. We obtained three karatasin extracts: one, the juice obtained by fruits expressing, and two more, the pulp and the peel parts extracted with NaCl 0.25, 0.50 and 0.80 M. The protein and activity was assayed by Bradford and caseinolytic methods, respectively.

RESULTS:

Yield (g/500 ml) of karatasin from the juice was 0.55, with a proteolytic activity of 136.7 mg Tir/mg protein. After trying a series of NaCl molarities, the highest yield of karatasin from peel parts (wastes) was 0.306 at NaCl 0.25 M (activity of 299 mg Tir/mg protein). The NaCl extraction of pulp part showed the highest yield (0.674) at NaCl 0.50 M (activity of 271 mg Tir/mg protein).

SIGNIFICANCE: These results show that NaCl extraction of B. karatas fruit peel, can be used to increase the yield and activity of karatasin, a new proteinase with potential for use in food applications, obtained from the fruit and its wastes.