Developing new insights into the natural source, structure, chemistry and catalytic properties of the substances associated with the energy fixing cycle of plants is a key element in understanding and harnessing the biosynthesis of organic compounds. This project proposes to carry out broad-based studies on the chemistry, synthesis and biosynthesis of porphyrins, chlorophylls, and other photosynthetic pigments. Several lines of investigation will be followed, these involving 1) studies of the biosynthesis of certain chlorophylls from green bacteria, using organic synthesis of radiochemically labeled precursors and feeding to a cell homogenate; 2) studies of the biological origins of certain unusual side-chains in these chlorophylls with respect to photosynthesis; 3) syntheses and characterization of novel products (such as chlorins, isobacteriochlorins, pyrrocorphins, hexahydroporphyrins, octahydroporphyrins) obtained by controlled site-selective reduction or photoreduction of porphyrins; 4) studies aimed at the organic synthesis of chlorophyll-a and its important divinyl analogue; 5) syntheses and characterization of the RCI- chlorophyll proposed to be in photosynthetic reaction centers; 6) studies of the biosynthesis of bacteriochlorophyll-a, using compounds synthesized in project and spectroscopic characterization, of the products of chlorophyll breakdown in senescent leaves and in fruit ripening; and finally, 8) studies of the biosynthesis of phycocyanobilin, an algal photosynthetic pigment, using syntheses of likely precursor molecules. All eight projects rely heavily upon synthetic organic chemistry and spectroscopic identity of products using physical techniques.
