Light scattering and viscosity study of Poly-L-methionine

Abstract

Poly-L-methionine samples have been produced by polymerization of L- methionine-N-carboxyanhydride and their properties studied by light scattering and viscometry in organic solvents. In trifluoroacetic acid viscosity studies reveal a polyelectrolyte effect, hence the poly-L-methionine is charged. Furthermore, it is a random coil and fits the same Mark-Houwink equation as does poly-γ-benzyl-L-glutamate in dichloroacetic acid. Poly-L-methionine is a helical rod in ethylene dichloride + 2% dichloroacetic acid and shows the same viscometric behaviour as poly-y-benzyl-L-glutamate in dimethylformamide. Comparison of five different organic soluble polypeptides shows that there is an approximate correlation between the rigidity of the helix and its stability.