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Abstract

This study reports on the purification and characterization of a cationic enzyme with chymotryptic activity from camel pancreas. The enzyme was purified 52-fold in a 48% yield by a three-step chromatographic procedure consisting of anion-exchange, cation-exchange and affinity chromatographies. The purified enzyme was homogeneous on gel isoelectric focusing and on SDS gel electrophoresis. Its isoelectric point was estimated to be 7.3 and its molecular mass was found to be 23,600 Da. The enzyme was identified as a cationic chymotrypsin according to its physiochemical properties, substrate specificity and susceptibility to inhibition. It was active towards esters of aromatic amino acids but much less active towards a leucine ester. In all cases, the k(cat) values of the camel enzyme were less than the corresponding values of bovine chymotrypsin A. It also showed a lower level of kininase activity. Camel chymotrypsin was more susceptible than its bovine equivalent to inhibition by soybean trypsin inhibitor and aprotinin. It showed the same pH optimum as bovine chymotrypsin A for its esterolytic activity, but was more dependent on CaCl2 for long-term stability.

Rapid Fabrication of Biocomposites by Encapsulating Enzymes into Zn-MOF-74 via a Mild Water-Based Approach

“…Furthermore, the crystal morphology was transformed from dispersed spindle-like (Zn-MOF-74 and CAT@Zn-MOF-74, Figure b and Figures S1 and S2) to flower-like crystals (CHT@Zn-MOF-74, Figure S23), in which small spherical spindle crystals were aggregated without changing the crystallinity. This phenomenon can be attributed to the easy deprotonation of the organic linker H 4 DOBDC because of its incubation with CHT (isoelectric point (pI) ∼ 7.3) during synthesis, which resulted in the acceleration of nucleation formations and subsequent quick generation of small crystallite aggregates . While in CAT@Zn-MOF-74, the pI of CAT ∼ 5.4 caused difficulty in the dehydrogenation of the linker H 4 DOBDC, which decreased the nucleation rate.…”