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B Testa

Publications and source records attributed to B Testa.

At least 91 records · Page 5Linked to original sources
PubMed1978

An ab initio study of electronic factors in metabolic hydroxylation of aliphatic carbon atoms.

The monooxygenase-mediated hydroxylations of aliphatic carbon atoms are known to be regioselective for positions alpha to heteroatoms or to pi systems (aromatic rings, carbon-carbon double bonds, carbonyl groups). Ab initio calculations (STO-3G and in some cases 4-31G) were performed on model molecules, indicating that the Mulliken overlap populations (taken as indices of electron bond densities) of Calpha-H bonds being regioselectively hydroxylated are larger than Cbeta-H and Cgamma-H overlap populations. These results support the hypothesis that metabolic C-hydroxylations occur by insertion of an activated oxygen species of electrophilic nature, probably oxene.

Carbon↗
PubMed1976

A reappraisal of the stereoselective metabolism of nicotine to nicotine-1'-N-oxide.

1. The cis and trans 1'-N-oxide metabolites of (2'R)-(+)-nicotine have the absolute configuration (1'S; 2'R) and (1'R; 2'R), respectively, and not the reverse as previously published. 2. Reinterpretation of metabolic data in the light of this reassignment reveals that N-oxidation of nicotine leads preferentially to the (1'R)-N-oxide, with little dependence on the configuration of the 2'-centre. 3. It is proposed that (2'S)-(-)-nicotine and (2'R)-(+)-nicotine bind to the same enzymic site by two distinct modes of binding; each of these modes involves the more basic centre (in this case the pyrrolidine ring) as the governing binding moiety.

Animals↗