Ribosyl Geometry in the Transition State of Streptococcus pneumoniae Methylthioadenosine Nucleosidase from the 3′- 2 H Kinetic Isotope Effect

ArticleinJournal of the American Chemical Society 130(35):11617-9 · October 2008with7 Reads
Impact Factor: 12.11 · DOI: 10.1021/ja804578m · Source: PubMed

    Abstract

    Synthesis of [3'-(2)H)-labeled 5'-methylthioadenosine (MTA) derivatives permitted measurement of the [3'-(2)H) KIE of the reaction catalyzed by Streptococcus pneumoniae methylthioadenosine nucleosidase (spMTAN). The key [3'-(2)H) KIE revealed the partial 3'-OH polarization and H3'-endo -> exo ribosyl configuration at the spMTAN transition state. A new understanding of the transition state stabilization of spMTAN-catalyzed hydrolysis is uncovered in structural features at the spMTAN transition state.