title: The proteolytic processing of amelogenin by enamel matrix metalloproteinase (MMP-20) is controlled by mineral ions.
abstract: BACKGROUND
  Enamel synthesis is a highly dynamic process characterized by simultaneity of matrix secretion, assembly and processing during apatite mineralization. MMP-20 is the first protease to hydrolyze amelogenin, resulting in specific cleavage products that self-assemble into nanostructures at specific mineral compositions and pH. In this investigation, enzyme kinetics of MMP-20 proteolysis of recombinant full-length human amelogenin (rH174) under different mineral compositions is elucidated.
  
  
  METHODS
  Recombinant amelogenin was cleaved by MMP-20 under various physicochemical conditions and the products were analyzed by SDS-PAGE and MALDI-TOF MS.
  
  
  RESULTS
  It was observed that mineral ions largely affect cleavage pattern, and enzyme kinetics of rH174 hydrolysis. Out of the five selected mineral ion compositions, MMP-20 was most efficient at high calcium concentration, whereas it was slowest at high phosphate, and at high calcium and phosphate concentrations. In most of the compositions, N- and C-termini were cleaved rapidly at several places but the central region of amelogenin was protected up to some extent in solutions with high calcium and phosphate contents.
  
  
  CONCLUSIONS
  These in vitro studies showed that the chemistry of the protein solutions can significantly alter the processing of amelogenin by MMP-20, which may have significant effects in vivo matrix assembly and subsequent calcium phosphate mineralization.
  
  
  CONCLUSIONS
  This study elaborates the possibilities of the processing of the organic matrix into mineralized tissue during enamel development.
authors.affiliation: Division of Biomaterials and Bioengineering, Department of Preventive and Restorative Dental Sciences, University of California, 707 Parnassus Avenue, San Francisco, CA 94143, USA.
authors.forename: Feroz
authors.initials: F
authors.lastname: Khan
authors.forename: Haichuan
authors.initials: H
authors.lastname: Liu
authors.forename: Aileen
authors.initials: A
authors.lastname: Reyes
authors.forename: H Ewa
authors.initials: HE
authors.lastname: Witkowska
authors.forename: Olga
authors.initials: O
authors.lastname: Martinez-Avila
authors.forename: Li
authors.initials: L
authors.lastname: Zhu
authors.forename: Wu
authors.initials: W
authors.lastname: Li
authors.forename: Stefan
authors.initials: S
authors.lastname: Habelitz
mesh_terms: D000566:Amelogenesis / Q000502:physiology; D053523:Amelogenin / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D001031:Apatites / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry*; D003743:Dental Enamel / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007700:Kinetics; D053519:Matrix Metalloproteinase 20 / Q000737:chemistry*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry*; D059748:Proteolysis; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012996:Solutions; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D053523:Amelogenin; D001031:Apatites; D010446:Peptide Fragments; D011994:Recombinant Proteins; D012996:Solutions; D053519:Matrix Metalloproteinase 20; D002118:Calcium