Identification and Structural Analysis of Ricin Inhibitors.

Abstract

Ricin is a potent cytotoxin which has been used by governments and terrorists as a poison. The three-dimensional structure of this toxic molecule was solved by X-ray crystallography, including an atomic description of its active site. The goal of this project was to use computer searches and other molecular modeling techniques to identify an inhibitor or ricin A chain (RTA). The program CHEM-X was used to predict that pteroic acid (PTA) would bind to RTA. This was shown to be the case by kinetic assays, where PTA protected ribosomes against the action of RTA, and by X-ray crystallography. The affinity of PTA is weak, with a Ki estimated at 600 Micrometers. The pterin group of PTA was observed to make many polar interactions with RTA within the specificity site of the enzyme, and to bind more strongly than the natural substrate adenine. Further work will be required to increase the binding affinity of this class of inhibitors, and to improve their solubility if efficacious antidotes are to be designed from this lead.

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Document Details

Document Type
Technical Report
Publication Date
Dec 01, 1996
Accession Number
ADA322174

Entities

People

  • Jon D. Robertus

Organizations

  • University of Texas at Austin

Tags

Communities of Interest

  • Biomedical

DTIC Thesaurus Topics

  • Biological Pigments
  • Chemical Compounds
  • Chemical Synthesis
  • Chemistry
  • Computer Programs
  • Computers
  • Crystallography
  • Inhibitors
  • Materials
  • Molecules
  • Nucleosides
  • Organelles
  • Structural Analysis
  • Terrorists
  • Three Dimensional
  • X Rays
  • X-Ray Crystallography

Fields of Study

  • Chemistry

Readers

  • Molecular and Cellular Biochemistry
  • Positioning, Navigation, and Timing (PNT) Technology.