Millisecond Laue structures of an enzyme-product complex using photocaged substrate analogs

Nat Struct Biol. 1998 Oct;5(10):891-7. doi: 10.1038/2331.


The structure of a rate-limited product complex formed during a single initial round of turnover by isocitrate dehydrogenase has been determined. Photolytic liberation of either caged substrate or caged cofactor and Laue X-ray data collection were used to visualize the complex, which has a minimum half-life of approximately 10 milliseconds. The experiment was conducted with three different photoreactive compounds, each possessing a unique mechanism leading to the formation of the enzyme-substrate (ES) complex. Photoreaction efficiency and subsequent substrate affinities and binding rates in the crystal are critical parameters for these experiments. The structure suggests that CO2 dissociation is a rapid event that may help drive product formation, and that small conformational changes may contribute to slow product release.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Catalysis
  • Crystallography, X-Ray / methods*
  • Isocitrate Dehydrogenase / chemistry*
  • Isocitrates
  • Kinetics
  • Models, Chemical
  • Models, Molecular
  • NADP / analogs & derivatives
  • Photolysis


  • Isocitrates
  • P(2')-(1-(4,5-dimethoxy-2-nitrophenyl)ethyl) nicotinamide adenine dinucleotide phosphate
  • caged isocitrate
  • NADP
  • Isocitrate Dehydrogenase

Associated data

  • PDB/1B15