Picomolar inhibitors as transition-state probes of 5′-methylthioadenosine nucleosidases

Jemy A. Gutierrez, Minkui Luo, Vipender Singh, Lei Li, Rosemary L. Brown, Gillain E. Norris, Gary B. Evans, Richard H. Furneaux, Peter C. Tyler, Gavin F. Painter, Dirk H. Lenz, Vern L. Schramm

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


Transition states can be predicted from an enzyme's affinity to related transition-state analogues. 5′-Methylthioadenosine nucleosidases (MTANs) are involved in bacterial quorum sensing pathways and thus are targets for antibacterial drug design. The transition-state characteristics of six MTANs are compared by analyzing dissociation constants (Kd) with a small array of representative transition-state analogues. These inhibitors mimic early or late dissociative transition states with Kd values in the picomolar range. Our results indicate that the Kd ratio for mimics of early and late transition states are useful in distinguishing between these states. By this criterion, the transition states of Neisseria meningitides and Helicobacter pylori MTANs are early dissociative, whereas Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae, and Klebsiella pneumoniae MTANs have late dissociative characters. This conclusion is confirmed independently by the characteristic [1′-3H] and [1′-14C] kinetic isotope effects (KIEs) of these enzymes. Large [1′-3H] and unity [1′-14C] KIEs are observed for late dissociative transition states, whereas early dissociative states showed close-to-unity [1′-3H] and significant [1′-14C] KIEs. Kd values of various MTANs for individual transition-state analogues provide tentative information about transition-state structures due to varying catalytic efficiencies of enzymes. Comparing Kd ratios for mimics of early and late transition states removes limitations inherent to the enzyme and provides a better predictive tool in discriminating between possible transition-state structures.

Original languageEnglish (US)
Pages (from-to)725-734
Number of pages10
JournalACS Chemical Biology
Issue number11
StatePublished - Nov 2007

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine


Dive into the research topics of 'Picomolar inhibitors as transition-state probes of 5′-methylthioadenosine nucleosidases'. Together they form a unique fingerprint.

Cite this