Quaternary Structure of Polynucleotide Phosphorylase from Escherichia coli: Evidence of a Complex between Two Types of Polypeptide Chains
Article first published online: 28 JUN 2008
European Journal of Biochemistry
Volume 55, Issue 3, pages 573–582, July 1975
How to Cite
PORTIER, C. (1975), Quaternary Structure of Polynucleotide Phosphorylase from Escherichia coli: Evidence of a Complex between Two Types of Polypeptide Chains. European Journal of Biochemistry, 55: 573–582. doi: 10.1111/j.1432-1033.1975.tb02194.x
- Issue published online: 28 JUN 2008
- Article first published online: 28 JUN 2008
- (Received August 6, 1974/March 5, 1975)
A new form of polynucleotide phosphorylase containing α and β subunits was isolated (form B) by purification without preparative electrophoresis; this form was compared to the enzyme obtained by preparative electrophoresis purification (form A).
The Stokes radius of these two forms are very different: 6.4 nm for form A and 8.7–9.0 nm for form B; on the other hand the sedimentation coefficients are close: 8.9 S and 9.9 S respectively. Such a result suggests that form B is very asymmetric. The apparent molecular weights, calculated from the Stokes radii and from the sedimentation coefficients, are approximately 365000 for form B and 252000 for form A. The latter is homogeneous on polyacrylamide gel, whereas the former yields two components, one of which behaves similarly to form A. Finally, whereas form A is composed of only one type of subunit, α, form B contains two types of chains: α (Mr 86000 ± 5000) and β (Mr 48000 ± 2000) in stoichiometric proportions.
From these results we believe that one should assume for form B the existence of a complex between form A and β chains; the role of the latter still remains to be specified.