Low molecular weight peptides of black sea cucumber (Holothuria atra) down-regulate MMP-1 in human dermal fibroblasts

Matrikines are signalling peptides that can stimulate collagen synthesis naturally in skin cells to promote wound healing and tissue repair. In this study, we collected Holothuria atra from Halmahera, Indonesia, to explore its small-sized peptide content as collagen stimulators. The sea cucumber body wall was digested by alcalase in 50 mmol/L phosphate buffer (pH 7 with E/S ratio of 5 % at 45 degrees C for 6 h), followed by fractionation using ultrafiltration membranes with 3, 5 and 10 kDa cut-offs. Fraction <3 kDa increased the collagen production in human dermal fibroblast cell lines by 200 % compared to control at 200 mu g/mL. The same fraction inhibited matrix-metalloproteinase I (MMP-1) by 70 % at 50 mu g/mL but only slightly modulated pro-TGF-beta 1. Repetitive chromatography of fraction <3 kDa yielded three tripeptides. The sequence of the isolated tripeptides was predicted using the Expasy PeptideCutter application to obtain GVV, PGT and GAQ. Tripeptide PGT was predicted as the most active collagen-stimulator compared to the other tested tripeptides using HPEPDOCK via MMP-1 inhibition. Interaction analysis of the PGT-MMP1 complex using LigPlot(+) revealed the presence of five hydrogen bonds between PGT and Leu181, Ala182, Glu 219, and Zn at the S1 active site of the protein receptor.