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Gelatinase‐mediated proteolysis of pigment epithelium‐derived factor (PEDF) is pH dependent
Author(s) -
Amaral Juan,
Notari Luigi,
StetlerStevnson William,
Becerra S. Patricia
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a648-d
Subject(s) - pedf , proteolysis , chemistry , biochemistry , tris , phosphate , serpin , gelatinase a , matrix metalloproteinase , metalloproteinase , enzyme , gene , retinal
The antiangiogenic and neurotrophic factor PEDF is a member of the SERPIN superfamily of proteins. We have shown before that the majority of proteinases cleave PEDF (50‐kDa) at its homologous serpin reactive loop leaving an active limited product of 46‐kDa, and that gelatinases (MMP‐2 and MMP‐9) can degrade PEDF abolishing its biological activities. In this study we characterized the MMP‐2 mediated proteolysis of PEDF. While MMP‐2 in phosphate buffer degraded PEDF in a calcium‐depended manner, activated MMP‐2 in Tris buffer pH 7.5 plus calcium only cleaved PEDF to a 46‐kDa product. Controlled chymotryptic proteolysis of PEDF in Tris and phosphate buffer plus CaCl 2 resulted in a 46‐kDa limited product, implying no change in folded conformation of the PEDF protein under these buffer conditions. Because the pH of phosphate buffer decreased with CaCl 2 , the effect of pH on MMP‐2 activity was examined. MMP‐2 in Tris/MES buffers had optimum activity at pH 5.5–6, with maximum autodegradation of the MMP‐2 polypeptide at this pH range. These results demonstrate that MMP‐2 can autoactivate in a pH‐dependent fashion and suggest a pH‐sensitive MMP‐2‐mediated degradation of PEDF. This work was supported by the Intramural Research Program of NEI and NCI, NIH.