Probability Description of Ligand--Receptor Interactions. Evaluation of Reliability of Events with Small and Supersmall Doses. I. Kinetics of Ligand--Receptor Interactions

K. G. Gurevich^* and S. D. Varfolomeev

Department of Chemical Enzymology, School of Chemistry, Lomonosov Moscow State University, Moscow, 119899 Russia; fax: (095) 939-5417; E-mail: GKG@bio.chem.msu.ru

^* To whom correspondence should be addressed.

Received January 19, 1999; Revision received March 23, 1999

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We have developed mathematical methods for describing ligand--receptor interactions (LRI) using Markov chains. Under some conditions, the mean value of ligand--receptor complexes obtained using Markov chains coincides with that obtained from the law of mass action. Using the calculated ratio of standard deviation to mean number of ligand--receptor complexes, we show that with small concentrations of ligand--receptor complexes LRI must be described using probability methods. Using data from the literature, we show that LRI description using the mass-action law under these conditions can cause significant errors in interpretation of experimental data.

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KEY WORDS: ligand--receptor interaction, Markov chains, small and supersmall doses

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