Aminopeptidase function of dinuclear zinc(II) complexes with chiral dinucleating ligands: Stereo selectivity by chiral substrate recognition

The aminopeptidase functions of newly obtained chiral dinuclear zinc(II) complexes [Zn-2(R-bppmp)(MeCO2)(2)]BPh4 (1R) and [Zn-2(S-bppmp)(MeCO2)(2)]BPh4 (1S) were estimated using l-leucine p-nitroanilide as a substrate [H(R/S-bppmp): 2,6-bis[{(R/S)-1-phenylethyl-2-pyridylmethyl}aminomethyl]-4-methylphenol]. Both complexes showed aminopeptidase activity, and a second-order rate equation was obtained as v = k [complex] [substrate]. The rate constants k were 3.3(7) x 10(-2) for 1R, and 7.6(5) x 10(-2) dm(3) mol(-1) s(-1) for 1S in a mixture of 40% DMF and 60% aqueous solution at pH 8.0, and the activity for 1S was 2.3 times greater than that for 1R. Molecular mechanics calculation indicated that IS is very suitable for substrate incorporation. (c) 2005 Elsevier B.V. All rights reserved.