The binding of copper ions to daunomycin and adriamycin

Using visible absorption, CD, ¹H nmr, and epr spectroscopy, the Cu(II) binging properties of daunomycin, adriamycin, and N-trifluoroacetyl daunomycin in water and ethanol have been explored. The drugs form two water soluble complexes having Cu-drug stoichiometries of 1:1 and 1:2, and with apparent pK_as of formation of 5.6 and 6.5, respectively. At pH values above ～8, the drugs form insoluble polymeric complexes with Cu(II). Similar species are also observed in ethanol. The structure of the compounds have been interpreted in terms of binding of the deprotonated hydroxyquinone portion of the drug to the copper ion. No evidence for the binding of the amino group on daunosamine was found.     

Specific heavy metal labeling of the 3-'terminus of phosphorothioate modified yeast tRNAPhe.

Yeast tRNAPhe containing a phosphorothioate modified -CS-CS-A terminus binds two moles of chloroterpyridineplatinum(II). This result was determined by titrating the tRNA with [3H](terpy)PtCl] Cl, removing excess platinum by cation exchange chromatography, and determining the amount of bound platinum by radiocounting techniques. It has thus been established that adjacent phosphorothioate modified nucleotides can be labeled with an electron dense stain, a necessary requirement for electronmicroscopic sequencing of polynucleotides to become practical.     

Cryomicroscopy of isolated plant protoplasts

It has been nearly 100 years since Müller-Thurgau (26) employed cryomicroscopy to identify the cooling rate dependency of intracellular ice formation. Since that time cryomicroscopy has advanced from the “ice age” when Molisch (23) packed his microscope in ice to the “space age” of today when computer hardware developed for space satellite imagery is used for cryomicroscopic image analysis. Although interest in cryomicroscopy has been sporadic in the intervening period, current interest is at a high level—largely as a result of the refinement in the cryomicroscope design by Diller and Cravalho (9). The increased sophistication in cryostage design and precision of temperature control allow for quantitative studies of cell behavior during a freeze-thaw cycle. Not only does quantitative video image analysis facilitate this task, but it provides for increased resolution of cellular and subcellular responses during the freeze-thaw cycle. Most importantly, cryomicroscopy presents a researcher with a panorama of cellular behavior within which existing facts can be placed in perspective and from which future experiments can be more accurately focused.