Z-FORM DNA EXIST IN THE BACTERIOPHAGE-LAM BDA

The site of the transition regions between the B- and Z-forms of the D NA duplex (B-Z junction) may serve as marker of the existence of Z-DNA in situ. The structure of (dC-dG)(10) insert in the bacteriophage lam bda gt10 has been studied in situ by modification of B-Z junction with O-beta-diethylaminoethylhydroxylamine (OHA). The latter is an analogu e of hydroxylamine possessing specificity with respect to unpaired cyt idine. This modification inhibited the process of restriction at BamHI site adjacent to the Z-insert. Judging by the extent of the inhibitio n about 5% of all inserts has been converted in Z-form. The certain ro le of Z-form at process of the packaging DNA into bacteriophage's caps id suggest.