Methods: Acetic acid was selected to extract the enamel matrix proteins. The N terminal amino acid sequence of enamel matrix proteins were determined with SDS-PAGE electrophoretic and blot membrnce analysis.

• 方法：选择乙酸提取法获得釉基质蛋白，采用SDS－PAGE电泳和印迹膜测序法分析N末端氨基酸序列。