METABOLISM OF BENZIMIDAZOLE IN WHEAT: II. FORMATION OF BENZIMIDAZOLE ADENINE DINUCLEOTIDE AND ITS PRODUCTS

A glycohydrolase (NAD nucleosidase) in the particulate fraction of wheat embryos catalyzes the splitting of the pyridinium N-ribosyl bond of NAD. The particles also catalyze the substitution of benzimidazole for the nicotinamide moiety of NAD. The products of the reaction, benzimidazole nucleoside and adenine nucleotide, probably arise by 5′-nucleotidase activity on benzimidazole adenine dinucleotide. An alternative mechanism has been proposed and the reaction is discussed in relation to the NAD-accelerated senescence of leaves of wheat and Elodea.

Cytotoxic Effect of Mycobacteria on Ehrlich Ascites Cells

Bekierkunst, Adam (Bryn Mawr College, Bryn Mawr, Pa.), and L. Joe Berry . Cytotoxic effect of mycobacteria on Ehrlich ascites cells. J. Bacteriol. 89: 205–211. 1965.— Mycobacterium tuberculosis , strains H 37 Rv, H 37 Ra, and BCG, release into a medium within 3 to 5 hr a substance that is toxic to Ehrlich ascites cells as evidenced by a diminished packed cell volume after 5 to 7 days of growth in the peritoneal cavity of mice. Cell-free extracts of the above strains of mycobacteria display the same type of cytotoxic effect, the strongest action being that of the virulent strain, H 37 Rv. The nicotinamide adenine dinucleotidase activity of surviving tumor cells was three to four times greater after treatment with the mycobacterial extracts than that of control cells. The cycotoxicity is probably due to cord factor, because 10 μg of this substance injected intraperitoneally into mice bearing Ehrlich ascites cells inhibited the growth of the cells to 50% of that of control cells. An increase in nicotinamide adenine dinucleotidase activity was found in surviving tumor cells after cord factor treatment.