Biophysics and Physicobiology
Online ISSN : 2189-4779
ISSN-L : 2189-4779
Regular Article
Effects of substrate conformational strain on binding kinetics of catalytic antibodies
Masayuki OdaTakeshi TsumurayaIkuo Fujii
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JOURNAL FREE ACCESS

2016 Volume 13 Pages 135-138

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Abstract

We analyzed the correlation between the conformational strain and the binding kinetics in antigen-antibody interactions. The catalytic antibodies 6D9, 9C10, and 7C8 catalyze the hydrolysis of a nonbioactive chloramphenicol monoester derivative to generate a bioactive chloramphenicol. The crystal structure of 6D9 complexed with a transition-state analog (TSA) suggests that 6D9 binds the substrate to change the conformation of the ester moiety to a thermodynamically unstable twisted conformation, enabling the substrate to reach the transition state during catalysis. The present binding kinetic analysis showed that the association rate for 6D9 binding to the substrate was much lower than that to TSA, whereas those for 9C10 and 7C8 binding were similar to those to TSA. Considering that 7C8 binds to the substrate with little conformational change in the substrate, the slow association rate observed in 6D9 could be attributed to the conformational strain in the substrate.

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© 2016 THE BIOPHYSICAL SOCIETY OF JAPAN
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