Human Amelogenin Degradation by MMP-20 in Tooth Enamel Development Studied by SDS PAGE, MALDI TOF MS and LC MS/MS.

摘要

Tooth enamel is the hardest tissue in the human body: it is built from closely packed, thin elongated hydroxyapatite (HAP) crystals. Biomineralization occurs within an extracellular protein matrix in developing tooth enamel. Initially, amelogenins (Amg) make up more than 90% of total protein in the matrix but in the process of enamel maturation, proteins are removed by proteolysis, mainly mediated by metalloproteinase 20 (MMP-20). Degradation of amelogenin can be altered by mineral binding affecting specificity and rate of proteolysis. Likewise, certain amelogenin mutations are associated with incomplete protein removal resulting in amelogenesis imperfecta. We have investigated the process of proteolysis, by MMP-20, of amelogenin bound to apatite and free in solution and studied the effects of a gene mutation on its degradation.