Two trinuclear copper [Cu I Cu I Cu I (L)] 1؉ complexes have been prepared with the multidentate ligands (L) 3,3 -(1,4-diazepane-1,4-diyl)bis(1-((2-(dimethylamino)ethyl)(methyl)amino)propan-2-ol) (7-Me) and (3,3 -(1,4-diazepane-1,4-diyl)bis(1-((2-(diethylamino) ethyl)(ethyl) amino)propan-2-ol) (7-Et) as models for the active site of the particulate methane monooxygenase (pMMO). The ligands were designed to form the proper spatial and electronic geometry to harness a ''singlet oxene,'' according to the mechanism previously suggested by our laboratory. Consistent with the design strategy, both [Cu I Cu I Cu I (L)] 1؉ reacted with dioxygen to form a putative bis( 3-oxo)Cu II Cu II Cu III species, capable of facile O-atom insertion across the central COC bond of benzil and 2,3-butanedione at ambient temperature and pressure. These complexes also catalyze facile O-atom transfer to the COH bond of CH 3CN to form glycolonitrile. These results, together with our recent biochemical studies on pMMO, provide support for our hypothesis that the hydroxylation site of pMMO contains a trinuclear copper cluster that mediates COH bond activation by a singlet oxene mechanism. density functional theory ͉ methane monooxygenase ͉ membrane-bound or particulate methane monooxygenase ͉ soluble methane monooxygenase ͉ mass spectroscopy T here presently is considerable interest in the development of efficient catalysts for the facile conversion of methane to methanol (1). Industrially, this is a difficult process. However, two methane monooxygenases (MMO) are known to mediate this process in methanotrophic bacteria: a membrane-bound MMO called particulate MMO (pMMO) and a water-soluble form referred to as soluble MMO (sMMO) (2). pMMO is a multicopper protein (3), and sMMO is a nonheme diiron protein (4, 5). Both systems exploit metal clusters to catalyze this difficult chemistry.The pMMO is found in all methanotrophs; in contrast, the sMMO has only been isolated from certain strains of methanotrophic bacteria. As an MMO, the oxidation of the COH bond often is described by the chemical equationSeveral possible mechanisms for the catalytic function of MMO have been considered. One involves a radical mechanism, wherein an activated ''oxygen'' species abstracts a hydrogen atom from the hydrocarbon substrate, followed by radical-rebound chemistry of the alkyl radical with the ''hot'' hydroxyl radical to form product. This mechanism has been implicated for the nonheme diiron cluster at the active site of sMMO (6-8). The other mechanism suggested by our laboratory invokes oxenoid or ''singlet oxene'' insertion across the COH bond (3). Evidence for a direct insertion mechanism has been provided by the turnover chemistry mediated by pMMO (9-12). Direct insertion of a singlet oxene across a COH bond should result in facile bond closure of the COO bond after formation of the OOH bond, and the process should proceed with full retention of configuration at the carbon center oxidized.Indeed, the hydroxylation of small straight-chain alkanes (C1-C5) me...

SpHox8 is the paralog group 8 Hox gene of Strongylocentrotus purpuratus. This identification follows from an analysis of the sequence of the complete open reading frame of a late-gastrula-stage cDNA clone; from direct linkage to adjacent Hox genes in a fosmid contig; and from blot hybridizations carried out on pulse field gel electrophoretic separations. SpHox8 is a single-copy gene, and there is only one Hox gene cluster per genome in S. purpuratus.