Article ID Journal Published Year Pages File Type
10532646 Analytical Biochemistry 2013 5 Pages PDF
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 and 60 °C because cHSA solutions are pasteurized at 60 °C. DPP-IV activity in cHSA was compared with other sources of albumin such as a recombinant albumin (rHSA). In addition, the production of DA-DKP was measured by negative electrospray ionization/liquid chromatography mass spectrometry (ESI−/LCMS). Significant levels of DPP-IV activity were present in cHSA. This activity was abolished using a specific DPP-IV inhibitor. Fully 70 to 80% DPP-IV activity remained at 60 °C compared with the 37 °C incubate. No DPP-IV activity was present in rHSA, suggesting that DPP-IV activity is present only 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.
Related Topics
Physical Sciences and Engineering Chemistry Analytical Chemistry
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