Mimics of cytochrome

In the present work, the construction of a mimic of cytochrome P-450 is attempted by in situ synthesis of iron-phthallocyanines in the supercages of zeolite Y and in the channels of VPI-5. Its catalytic activity and selectivity is tested in the oxyfunctionalization of n-alkanes with tertiary butyl hydroperoxide. 

II. REPLACEMENT OF THE PROXIMAL HISTIDINE LIGAND IN Mb INTO CYSTEINE OR TYROSINE PROTEIN MIMICS OF CYTOCHROME... 

A FePc complex encaged in the zeolite Y supercages, in its turn, can be wrapped in a polydimethylsiloxane membrane, thus acting not only as a mechanistic but also as a formal mimic of Cytochrome P450 often found in cell membranes.[57] Such membranes, contacted on one side with substrate and on the other side with oxidant, catalyse oxygenation reactions in a membrane reactor in the absence of any solvent, the majority of the product amount being recovered from the more polar phase. 

Such metal-complexed nitrenes were also generated by the reaction of (tosyliminoio-do)benzene (106) with Mn(m)- or Fe(n)-tetraphenylporphyrin, 107, in a mimic of cytochrome P-450 but with a tosylimino group instead of an oxygen atom on the metals (108) [179]. It was able to functionalize cyclohexane solvent, by nitrogen insertion into a C-H bond to form 109. Furthermore, the metalloporphyrins also catalyzed an intramolecular nitrogen insertion converting 110 into 111 [180]. 

To create artificial enzymes that could bind substrates in water solution with defined geometry, we examined dimers of cyclodextrins. As mentioned above, we used such dimers in mimics of hydrolytic enzymes [119, 120]. Now we wished to use them for mimics of cytochrome P-450. 

The encapsulated MePc in Y zeolite can be considered as a formal mimic of cytochrome P450, the rigid zeolite environment becoming a substitute for the flexible amino-acid environment of the natural enzyme [17]. After embedding in a polydimcthylsiloxanc (PDMS) membrane, the MePcY is able to function in a membrane reactor, and mimic the performance of the natural cytochrome P450 in a cell membrane. 

The Mn =0 entity is a very powerful oxidant able to mediate two different types of oxidative reactions transfer of an oxygen atom on a substrate (mimic of cytochrome P450, Fig. 21A) or electron abstraction (mimic of peroxidase. Fig. 21B). It is formally written Mn =0 since it corresponds to a two-electron oxidation with respect to the initial Mn complex. However,... 

METALLOPORPHYRINS AS CHEMICAL MIMICS OF CYTOCHROME P450 SYSTEMS 301... 

Synthetic metalloporphyrins have received a lot of recent attention as mimics of numerous enzymes. In addition, 10 models have been developed for peroxidases and particularly, ligninases. Metalloporphyrins have also found utility as model systems for studies of the oxidative metabolism of drugs.A detailed study of the metabolism of lidocaine has been reported, as have preliminary studies on the use of metalloporphyrins as chemical mimics of cytochrome P450 systems (Scheme 29.24). ... 

Parton, R.F. Vankelecom, I.F.J. Casselman, M.J.A. Bezoukhanova, C.P. Uytterhoeven, J.B. Jacobs, P.A. An efficient mimic of cytochrome P-450 from a zeolite-encaged iron complex in a polymer membrane. Nature 1994, 370 (6490), 541 -544, and references therein. 

---