[Quaternary structure of Escherichia coli polynucleotide phosphorylase: chemical characterization of form A].

We had previously shown the existence of two classes of polynucleotide phosphorylases : Form A which is made of alpha chains and carries the catalytic sites ; and form B which is constituted of alpha chains and of beta chains. We performed some chemical analyses of form A (N-terminal sequence, amino acid composition, peptide mapping) which suggest that the alpha chains are all identical and moreover that they have no relationship with the beta chains. The latter do not therefore derive from a partial proteolytic degradation of the alpha chains and can therefore be considered as true subunits of the enzyme.

[Analysis of a small quatity of polypeptides by two-dimensional electrophoresis: application to characterization of proteins].

A new two-dimensional electrophoresis is described. The first electrophoresis is performed in a 10 p. cent gel (1 X 110 mm) in the presence of 7 M urea; the migration in the second dimension proceeds on a 20 p.