K. Lemone Yielding

Direct in vitro photoaffinity labeling of DNA with daunorubicin, adriamycin, and rubidazone.

Irradiation by daylight fluorescent lamps, of a physical complex of duplex DNA with either daunorubicin, adriamycin, or rubidazone produced covalent adducts to DNA. The photoincorporated drug could not be extracted by phenol extraction which removed 99% of the non-photolyzed drug from its physical complex with DNA. The photoadduct was also stable to dialysis, Mg2+ addition, column chromatography, and thermal denaturation and alkali treatment of the DNA. The photoinduced adduct was proportional to the amount of incident irradiation, and the amount of DNA present, and as much as 30--45% of the drug which was physically associated could be photoincorporated. The drugs were not incorporated extensively into single-stranded DNA which lacks the ability to bind these antitumor agents by intercalation. Although the photochemical mechanisms of photoaffinity labeling DNA with these antineoplastic agents are unknown, this approach may prove to be useful for trageting their cellular sites of actions.

Spectral evidence for an intermediate in the glutamate dehydrogenase catalyzed reduction of NAD+ by glutamate☆

Abstract The progress curves for glutamate dehydrogenase catalyzed reduction of NAD during approach to steady state were divided into fast and slow components. The reaction product during the initial fast phase showed a substantial blue shift with respect to the slow phase or steady state, indicating the formation of a transient enzyme-bound intermediate.