Specific fragmentation of DNA heteroduplex molecules of two bacteriophage   mutants with endonucleaseSI from Aspergillus oryzae

Abstract

Heteroduplex DNA molecules of two bacteriophage mutants (lambda b2 and lambda i434ct68) were obtained by the method of molecular hybridization. These heteroduplexes possessed two types of loops formed as a result of: a) deletion in one of the DNA strands; and b) substitution of a DNA fragment for nonhomological one. The digestion of heteroduplexes with single-stranded specific nuclease SI from Aspergillus oryzae produced two fragments at 37 degrees C and three ones at 55 degrees C. The separation of fragments and determination of their molecular weight were carried out by means of electrophoresis in agarose. The molecular weights both measured and preliminarily calculated proved to be close. One of the fragments was identificated by its biological activity in CaCl2-dependent infectious system with helperphage.

DNA Cloning and the Analysis of Plasmid Structure and Function

“…Fragments of cloned DNA recovered from this type of construction are likely either to be missing some of the'terminal sequences of the original cloned fragment or to contain some of the cloning vector DNA. In the case of P9ly dA-dT joined DNA fragments it may be possible to selectively digest the junction DNA by treatment with single strand-specific endonuclease under mildly denaturing conditions (Hofstetter et al, 1976;Ksenzenko et al, 1976) .…”