Human CYP3A is the most abundant P450 isozyme present in the human liver and small intestine, and metabolizes around 50% of medical drugs on the market. The human CYP3A subfamily comprises four members (CYP3A4, CYP3A5, CYP3A7, CYP3A43) encoded on human chromosome 7. However, transgenic mouse lines carrying the entire human CYP3A cluster have not been constructed because of limitations in conventional cloning techniques. Here, we show that the introduction of a human artificial chromosome (HAC) containing the entire genomic human CYP3A locus recapitulates tissue- and stage-specific expression of human CYP3A genes and xenobiotic metabolism in mice. About 700 kb of the entire CYP3A genomic segment was cloned into a HAC (CYP3A-HAC), and trans-chromosomic (Tc) mice carrying a single copy of germline-transmittable CYP3A-HAC were generated via a chromosome-engineering technique. The tissue- and stage-specific expression profiles of CYP3A genes were consistent with those seen in humans. We further generated mice carrying the CYP3A-HAC in the background homozygous for targeted deletion of most endogenous Cyp3a genes. In this mouse strain with 'fully humanized' CYP3A genes, the kinetics of triazolam metabolism, CYP3A-mediated mechanism-based inactivation effects and formation of fetal-specific metabolites of dehydroepiandrosterone observed in humans were well reproduced. Thus, these mice are likely to be valuable in evaluating novel drugs metabolized by CYP3A enzymes and in studying the regulation of human CYP3A gene expression. Furthermore, this system can also be used for generating Tc mice carrying other human metabolic genes.

We studied the kinetics of the Diels-Alder reaction of Li(+)-encapsulated [60]fullerene with 1,3-cyclohexadiene and characterized the obtained product, [Li(+)@C60(C6H8)](PF6(-)). Compared with empty C60, Li(+)@C60 reacted 2400-fold faster at 303 K, a rate enhancement that corresponds to lowering the activation energy by 24.2 kJ mol(-1). The enhanced Diels-Alder reaction rate was well explained by DFT calculation at the M06-2X/6-31G(d) level of theory considering the reactant complex with dispersion corrections. The calculated activation energies for empty C60 and Li(+)@C60 (65.2 and 43.6 kJ mol(-1), respectively) agreed fairly well with the experimentally obtained values (67.4 and 44.0 kJ mol(-1), respectively). According to the calculation, the lowering of the transition state energy by Li(+) encapsulation was associated with stabilization of the reactant complex (by 14.1 kJ mol(-1)) and the [4 + 2] product (by 5.9 kJ mol(-1)) through favorable frontier molecular orbital interactions. The encapsulated Li(+) ion catalyzed the Diels-Alder reaction by lowering the LUMO of Li(+)@C60. This is the first detailed report on the kinetics of a Diels-Alder reaction catalyzed by an encapsulated Lewis acid catalyst rather than one coordinated to a heteroatom in the dienophile.

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Much higher reactivity of [Li(+)@C60]PF6(-) for Diels-Alder cycloaddition toward cyclopentadiene (CpH), in comparison with that of empty C60, was observed. The synthetic method, electrochemical and light absorption properties, and X-ray crystal structure of the product [Li(+)@C60(CpH)]PF6(-) are discussed.

Abstract-In this paper, we discuss a target-enclosing problem for a group of multiple nonholonomic agents in a plane. The proposed strategies guarantee that multiple agents' coordination finally results in a circular formation enclosing the targetobject which moves in the plane. Firstly, virtual agents for the feedback linearization of the real nonholonomic agents are introduced. Secondly, we propose the target-enclosing control laws based on the consensus algorithm to the virtual agents. Algebraic graph theory and consensus algorithm are employed to prove convergence and stability of the enclosing problem. Finally, experiments are provided to demonstrate the effectiveness of the proposed control laws.