OPTICAL PROPERTIES OF BIOLOGICAL MACROMOLECULES

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The object of this project is to increase and extend the usefulness of circular dichroism to the study of macromolecular structure. During the coming year, efforts will be centered on the following areas: (a) polypeptide CD; (b) heme proteins; (c) dyes and nucleotides binding to dehydrogenases and kinases; and (d) actinomycin-DNA interactions. Further calculations on nonplanar peptides will be performed, as will studies of the twisted beta-sheets which are ubiquitous in proteins. For the latter, two models have recently been proposed, which will be used to provide idealized geometries. Real geometries taken from high resolution X-ray structures will also be considered. Experimental studies on the CD of myoglobin and monomeric hemoglobins reconstituted with modified porphyrins will be continued. Affinity chromatography with immobilized apomyoglobin will be used to try to resolve enantiomers of vanadyl porphyrins. Oriented films of cytochrome oxidase will continue to be studied with emphasis on obtaining improved quality in the films and extension to infrared studies. Studies of Ca ion 2-dependent ATPase in sarcoplasmic reticulum will also be initiated. The CD of tetraiodofluorescein and bromphenol blue bound to a series of kinases and dehydrogenases will be investigated. Ethenoadenine analogs of ATP and ADP will be utilized as well. Theoretical calculations on actinomycin-DNA interactions will be initiated. The CD of free actinomycin will first be treated theoretically. If these calculations are successful, studies of actinomycin complexes with dCpG and with DNA, following the model of Sobell and Jain, will be undertaken.