A spectroscopic study of the binding of N-7-substituted cap analogues to human protein synthesis initiation factor 4E |
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Authors: | S E Carberry E Darzynkiewicz J Stepinski S M Tahara R E Rhoads D J Goss |
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Affiliation: | Department of Chemistry, Hunter College, City University of New York, New York 10021. |
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Abstract: | The binding of N-7-substituted cap analogues to eIF-4E from human erythrocytes is described. Data presented here indicate that there is a correlation between the tightness of binding of these cap analogues to eIF-4E and their potency as inhibitors of protein synthesis. This result indicates that the inhibitory activity of the cap analogues is strictly a function of the affinity of the analogue for eIF-4E under equilibrium conditions. The pH dependence of binding of the cap analogues to eIF-4E indicates that the enolate form of the cap is preferred, as originally postulated by Rhoads et al. [(1983) Biochemistry 22, 6084-6088]. Data indicate that there are differences in the mode of binding of alkyl-substituted and aryl-substituted cap analogues to eIF-4E arising from favorable interactions of the phenyl ring with the guanosine moiety. These differences may explain the enhanced recognition of the aryl-substituted cap analogues by eIF-4E. |
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