title: Substrate binding of gelatinase B induces its enzymatic activity in the presence of intact propeptide.
abstract: Expression of gelatinase B (matrix metalloprotease 9) in human placenta is developmentally regulated, presumably to fulfill a proteolytic function. Here we demonstrate that gelatinolytic activity in situ, in tissue sections of term placenta, is co-localized with gelatinase B. Judging by molecular mass, however, all the enzyme extracted from this tissue was found in a proform. To address this apparent incongruity, we examined the activity of gelatinase B bound to either gelatin- or type IV collagen-coated surfaces. Surprisingly, we found that upon binding, the purified proenzyme acquired activity against both the fluorogenic peptide (7-methoxycoumarin-4-yl)-acetic acid (MCA)-Pro-Leu-Gly-Leu-3-(2,4-dinitrophenyl)-l-2,3-diaminopropionyl-Ala-Arg-NH(2) and gelatin substrates, whereas its propeptide remained intact. These results suggest that although activation of all known matrix metalloproteases in vitro is accomplished by proteolytic processing of the propeptide, other mechanisms, such as binding to a ligand or to a substrate, may lead to a disengagement of the propeptide from the active center of the enzyme, causing its activation.
authors.affiliation: Department of Medicine, Division of Dermatology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Bannikov
authors.forename: Tatiana V
authors.initials: TV
authors.lastname: Karelina
authors.forename: Ivan E
authors.initials: IE
authors.lastname: Collier
authors.forename: Barry L
authors.initials: BL
authors.lastname: Marmer
authors.forename: Gregory I
authors.initials: GI
authors.lastname: Goldberg
mesh_terms: D001665:Binding Sites; D019281:Dimerization; D004792:Enzyme Precursors / Q000378:metabolism*; D005260:Female; D006801:Humans; D007700:Kinetics; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D019278:Matrix Metalloproteinase 3 / Q000494:pharmacology; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D013379:Substrate Specificity; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000494:pharmacology
chemical_list: D004792:Enzyme Precursors; D061965:Matrix Metalloproteinase Inhibitors; D019715:Tissue Inhibitor of Metalloproteinase-1; D019278:Matrix Metalloproteinase 3; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9