The relative molecular mass of collagen is large. There are 3 swimming bands in the electrophoresis image. The 2 swimming bands that appear near 100kD are the α1 chain and the α2 chain of the collagen molecule, respectively. The 1 swimming band that appears near 200kD is the β chain of the collagen molecule. That is, the relative molecular mass of each polypeptide chain of collagen can reach 100kD, and the relative molecular mass of one collagen molecule is 300kD. The determination methods of polypeptide molecular weight are commonly used SDS-PAGE, gel chromatography and mass spectrometry. Some people use gel filtration chromatography to determine the molecular weight distribution of collagen hydrolysate in dechromized leather scraps at about 16.1kD. The molecular weight distribution of flounder skin collagen oligopeptides determined by time-of-flight mass spectrometry mainly concentrated in 0.6-1.8kD. The molecular weight of the collagen polypeptide hydrolyzed by animal protease is 2-7kD, which is wider than that of the collagen polypeptide hydrolyzed by plant protease.
