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Dipeptidyl peptidase IV activity in commercial solutions of human serum albumin.


Anal Biochem. 2013 Jun 13;


Authors: Bar-Or D, Slone DS, Mains CW, Rael LT


Abstract

Due to the heterogeneous nature of commercial human serum albumin (cHSA), other components, such as the protease dipeptidyl peptidase IV (DPP-IV), possibly contribute to the therapeutic effect of cHSA. Here, we provide evidence for the first time that DPP-IV activity contributes to the formation of aspartate-alanine diketopiperazine (DA-DKP), a known immunomodulatory molecule from the N-terminus of human albumin. cHSA was assayed for DPP-IV activity using a specific DPP-IV substrate and inhibitor. DPP-IV activity was assayed at 37°C and 60°C since cHSA solutions are pasteurized at 60°C. DPP-IV activity in cHSA was compared to other sources of albumin such as a recombinant albumin (rHSA). Also, the production of DA-DKP was measured by ESI(-)/LCMS. Significant levels of DPP-IV activity were present in cHSA. This activity was abolished using a specific DPP-IV inhibitor. 70-80% DPP-IV activity remained at 60°C compared to the 37°C incubate. No DPP-IV activity was present in rHSA suggesting that DPP-IV activity is only present in HSA produced using the Cohn fractionation process. The formation of DA-DKP at 60°C was observed with the DPP-IV inhibitor significantly decreasing this formation. DPP-IV activity in cHSA results in the production of DA-DKP which could account for some of the clinical effects of cHSA.

PMID: 23770236 [PubMed - as supplied by publisher]