Towards Antibody-Mediated Metallo-Porphyrin Chemistry
An attempt was made to mimic cytochrome P-450-like activity using antibodies elicited against metallo-porphyrins. Monoclonal antibodies raised against a water-soluble Sn(1V) porphyrin complex (1) exhibited Specificity for a variety of monomeric metalloporphyrins, as well as for the b-0x0-Fe(III) porphyrin dimer 2. Some antibodies were found to be more selective for the monomer 1 than for the dimer 2, suggesting an "edge-on" recognition of the planar porphyrin molecule. The catalytic activity of the antibody-metalloporphyrin complexes was investigated using the epoxidation of styrene by iodosobenzene as a model reaction. Three biphasic media were studied for this reaction: reverse micelles, microemulsions, and solid catalyst in organic solvent. The most promising results were obtained with solid catalyst (obtained via lyophilization of equimolar amounts of Mn(TCP)Cl and specific antibody) in dry CHzClz at room temperature, as indicated by the high turnover numbers of the catalyst. A difference in the relative activity of the various monoclonal antibodies (MABs) was noted. The anti-1 antibodies displayed ca. 30-60% higher activity compared to a nonrelevant MAB.