We will attempt to apply photochemical techniques to three specific biological problems. The first deals with photolabeling, isolation and characterization of the regulatory molecule, whose function it is to modulate the synthesis of HMG CoA reductase, the regulatory step in cholesterol biosynthesis. The second problem involves the development of photolabile protecting groups for the preparation of monoallylic phosphate esters, the difficult to prepare substrates for terpene biosynthesis. Finally we will synthesize detergents suitable for detergent-protein complex formation such that the detergent can be decomposed to non-detergent products by a photo-cleavage reaction in order to recover the protein.