Partial purification and characterization of selected enzymes of bovine nitrogen metabolism : comparison of the Nguni and Hereford breeds

Abstract

Ruminant animals consuming low N-diet have been reported to have increased urea reabsorption with the Nguni being categorized as N-recycling ruminant. The enzymes associated with N-cycling are hypothesized to contribute to survival of the Nguni in harsh conditions. Enzymes responsible for such a function needed to be characterized in order to determine their effect in the functioning of the Nguni as opposed to Hereford breed. Crude enzymes from both breeds were separated from most or some contaminants by sephadex G-25, DEAE sephacel, and different affinity column chromatography. CPS and GDH were successfully purified and characterized by LC-MS/MS and further analysed by ProteinPilot™, blasted and matched >95% with those of Bos Taurus. Comparison of characterized enzymes and those which failed to ionise such as ARG, GS and GA was done using kinetics and graphs annotating specific activities. Partial purification and characterization was in part achieved.