Acrylamide gel electrophoresis of bacteriophage Qβ: Electrophoresis of the intact virions and of the viral proteins

Bacteriophage Qβ can be separated easily from several other RNA-containing bacteriophages by electrophoresis on large-pore acrylamide gels. The mobilities of these viruses depend both upon the acrylamide and cross-linker concentrations. Qβ has a complex electrophoretic pattern due to aggregation. An electrophoretic mutant of Qβ (called QβE1) has been isolated and partially characterized. The proteins of Qβ, QβE1, R17, and G17 have been characterized by acrylamide gel electrophoresis. Two continuous SDS-containing systems have been used: an SDS-urea-phosphate gel at pH 7.6 and an SDS-urea-phosphate gel at pH 11.9. On these, the coat proteins of Qβ and R17 and also their A proteins are separable because they differ in molecular weight. The molecular weight of the A protein of Qβ is 37,600 daltons. The coat protein of Qβ and its electrophoretic mutant QβE1 are also distinguishable though they differ by only a single charged amino acid. A low pH buffer system containing formic acid and urea but lacking SDS separates the coat proteins of Qβ, QβE1, and R17 readily