Purin-6-yl 6-deoxy-1-thio-beta-D-glucopyranoside. Enzymology, chemistry, and cytotoxicity

Purin-6-yl 6-deoxy-1-thio-beta-D-glucopyranoside (4) is a substrate for almond beta-glucosidase and a weak competitive inhibitor of bovine liver beta-D-glucuronidase (Ki approximately 20mM). Both 4 and purine-protonated 4 undergo hydrolysis catalyzed by dilute acid in the pH range 0.17-2.59. These results are compared with those previously obtained with ammonium (purin-6-yl 1-thio-beta-D-glucopyranosid)uronate, (purin-6-yl 1-thio-beta-D-glucopyranosid)uronamide, purin-6-yl 1-thio-beta-D-glucopyranoside, and purin-6-yl 2-deoxy-1-thio-beta-D-glucopyranoside, and it is concluded that the data support an involvement of substituents at C-5 in producing productive Michaelis-complex conformers. The 6-deoxyglucoside is more active than the D-glucosiduronic acid in an L1210 mouse screen.     

6. MIGRATION NOTES,CHINSALI, NORTHERN RHODESIA

Jarvis, M. J. F. &; Currie, M. H. 1979. Breeding of captive Knysna and Purplecrested Louries. Ostrich 50:38-44.

Knysna Louries Tauraco corythaix and Purplecrested Louries T. porphyreolophus were studied in captivity to determine food requirements and feeding habits, clutch size, egg measurements, incubation periods, as well as the nestling period, anatomical and behavioural development of chicks, and aspects of parental behaviour.     

Site-specific mutagenesis induced by single O6-alkylguanines (O6-n-propyl, O6-n-butyl, O6-n-octyl) in vivo.

The mutagenic activity of a series of longer chain O6-n-alkylguanine residues (O6-n-propyl, O6-n-butyl, O6-n-octyl) has been analyzed using a plasmid molecule (pUC 9) in which single O6-alkylguanines were positioned in the unique Pstl recognition site by shot gun ligation (Nucleic Acids Res. 13, 3305-3316 (1985)) of overlapping synthetic oligonucleotides. After transfection of these vectors into E. coli cells having normal DNA repair systems, progeny plasmids were produced, of which 2.6%, 2.8% and 4.3% were mutated in their Pstl site when containing O6-n-propylguanine, O6-n-butylguanine, O6-n-octylguanine, respectively. DNA sequence analysis of mutant plasmid genomes revealed that O6-n-propylguanine and O6-n-butylguanine induced exclusively G-->A transitions located specifically at the preselected site. O6-n-octylguanine induced apart from G-->A transitions (70%) also targeted G-->T transversions (30%). These results indicate that the mutation frequency of longer chain O6-alkylguanines can be substantial in cells with normal repair systems and that the mutation pattern depends on the nature of the alkyl group.     

Photochemical dehydrogenation of 5, 6-dihydropyrimidines.

5, 6-Dihydropyrimidines can be oxidized photochemically to the original pyrimidines with light of lambda greater than 300 nm in the presence of transition metal salts which act as sensitizers. A hydrogen atom abstraction by hydroxyl radical is suggested as the reaction mechanism.