This project surveys biochemical practice and sets the record straight regarding which parts of protein classification are pluralist. Assuming an approach that attempts to draw metaphysical conclusions by analyzing how multifaceted practices of science work, I tie the results of my survey of protein classification practices to the debate over natural kinds. I address which classificatory practice is likely to pick out a natural kind. I defend the thesis that dynamics is a fundamental description of proteins as kinds. This view is widely held in biochemistry but is absent from philosophical literature on biochemical kinds.