Diprotin A is a tripeptide inhibitor of dipeptidyl peptidase 4 (DPP-4; IC50 = 1.1 μg/ml).1 It inhibits degradation of glucagon-like peptide 1 in culture with insulin-secreting BRIN-BD11 rat pancreatic β-cells when used at a concentration of 25 μM.2 Diprotin A (5 mg/ml) pre-incubation enhances chemotaxis of murine embryonic stem cells towards stromal cell-derived factor-1 (SDF-1/CXCL12) in vitro.3 Pre-incubation of CD34+ human umbilical cord blood cells with diprotin A (5 mM) prior to injection increases engraftment in NOD/SCID recipient mice.4
1.Umezawa, H., Aoyagi, T., Ogawa, K., et al.Diprotins A and B, inhibitors of dipeptidyl aminopeptidase IV, produced by bacteria.J. Antibiot. (Tokyo)37(4)422-425(1984) 2.Green, B.D., Liu, H.K., McCluskey, J.T., et al.Function of a long-term, GLP-1-treated, insulin-secreting cell line is improved by preventing DPP IV-mediated degradation of GLP-1Diabetes Obes. Metab.7(5)563-569(2005) 3.Guo, Y., Hangoc, G., Bian, H., et al.SDF-1/CXCL12 enhances survival and chemotaxis of murine embryonic stem cells and production of primitive and definitive hematopoietic progenitor cellsStem Cells23(9)1324-1332(2005) 4.Campbell, T.B., Hangoc, G., Liu, Y., et al.Inhibition of CD26 in human cord blood CD34+ cells enhances their engraftment of nonobese diabetic/severe combined immunodeficiency miceStem Cells Dev.16(3)347-354(2007)