Richard C. Hom

Guanidine group specific ADP-ribosyltransferase in murine cells

We have identified a guanidine group specific ADP-ribosyltransferase activity, capable of transferring an ADP-ribose group from NAD to a low molecular weight guanidine compound [p-(nitrobenzylidine)amino]guanidine and proteins such as histone and poly-L-arginine, in a variety of murine cell lines. The enzyme activity appears to be associated with an integral membrane protein of apparent molecular weight 30-33 kDa. Incubation of the viable cells in isotonic phosphate buffered saline with [32P]NAD results in the incorporation of label into cellular proteins. Dimethyl sulfoxide treatment of the cells downregulates the transferase activity as well as the ADP-ribosylation of cell proteins with extracellular NAD.

Time‐domain measurements of pressure‐induced frequency shifts in methyl chloride and ethylene oxide

Pressure‐induced rotational frequency shifts at microwave frequencies have been measured in the time domain. The computerized technique involves using the Stark effect to move molecules into resonance with an incident microwave field. The heterodyned emission decay signals can then be fitted for the frequency and relaxation time. Measurements are reported for the three J = 0–1 hyperfine transitons of CH3 35Cl and three ethylene oxide transitions 211–202, 321–330, and 431–422.