Prolyl-glycyl-proline Peptide

Proline-glycine-proline (PGP) is a tripeptide molecule and an established biomarker for chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF). PGP functions as a neutrophil chemoattractant and is derived from the proteolytic cleavage of collagen in the extracellular matrix by a multistep cascade. First, the matrix metalloproteases MMP-8 or MMP-9 cleave collagen to peptides 30-100 amino acids in length. Prolyl endopeptidase further cleaves the collagen fragments to PGP. PGP and the related peptide N-acetylated PGP act through chemokine receptors CXCR1 and CXCR2 on neutrophil cells. Patients with cystic fibrosis have been shown to have elevated levels of PGP peptides in sputum. PGP, but not N-acetylated PGP, has been demonstrated to be a substrate for the pro-inflammatory enzyme LTA4 hydrolase.