Affinity chromatography polymers with suitable substrates are synthesized to elucidate the function and structure of each component of Pseudomonas putida comphor, 11-deoxycortisol-and benz (alpha) pyrene- hydroxylases. Riboflavin, FMN and FAD are also immobilized on suitable polymers to study enzymes related to flavins. ESR work using nitric oxide and model hee prosthetic groups will clarify the presenceof a sulfur axial ligand of P-450's and the mechanism of P-420 reactivation to P-450.