[35S]GTP gamma S binding studies of amphiphilic drugs-activated Gi proteins: a caveat

Bioorg Med Chem Lett. 2009 Apr 15;19(8):2224-9. doi: 10.1016/j.bmcl.2009.02.097. Epub 2009 Feb 28.

Abstract

This paper documents a serious problem met during the testing of Gi protein-activating properties of a new series of synthetic compounds by measuring the induced binding of [(35)S]GTPgammaS to different subtypes of Gi protein. The problem arose from the strong affinity between [(35)S]GTPgammaS and the tested compounds, that are characterized by several (2-4) positive charges and high lipophilicity. Apparently, such affinity yields insoluble, labelled complexes that, also in the absence of Gi protein, are retained on the filters and give rise to false positive results.

Publication types

  • Comparative Study

MeSH terms

  • Drug Evaluation, Preclinical / adverse effects
  • GTP-Binding Protein alpha Subunits, Gi-Go / chemistry
  • GTP-Binding Protein alpha Subunits, Gi-Go / metabolism*
  • Guanosine 5'-O-(3-Thiotriphosphate) / chemistry
  • Guanosine 5'-O-(3-Thiotriphosphate) / metabolism*
  • Hydrophobic and Hydrophilic Interactions
  • Protein Binding / drug effects
  • Protein Binding / physiology
  • Solubility
  • Sulfur Radioisotopes / metabolism
  • Surface Tension / drug effects
  • Surface-Active Agents / chemistry
  • Surface-Active Agents / metabolism*
  • Surface-Active Agents / pharmacology*

Substances

  • Sulfur Radioisotopes
  • Surface-Active Agents
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • GTP-Binding Protein alpha Subunits, Gi-Go