The opposite effect of K+ and Na+ on the hydrolysis of linear and cyclic dipeptides |
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Authors: | Thomas D. Campbell Clara A. Hart Rio Febrian Mark L. Cheneler Paul J. Bracher |
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Affiliation: | Department of Chemistry, Saint Louis University, St. Louis, MO 63103, USA |
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Abstract: | Potassium and sodium are generally considered inert ‘spectator’ ions for organic reactions. Here, we report rate constants for the acid-promoted hydrolysis of the seven dipeptides of glycine (G) and alanine (A) and an unexpected pattern in how these rates differ in the presence of K+ and Na+. The linear dipeptides hydrolyze 12–18% percent slower in the presence of KCl versus an equal concentration of NaCl, while the cyclic dipeptides hydrolyze 5–13% faster in the presence of KCl (all P-values?0.025). We believe this is the first report of a general organic reaction—here, amide hydrolysis—for which some substrates react faster in the presence of K+ and others in Na+. The results offer a potential reason for life’s mysterious universal selection of intracellular potassium over sodium. |
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Keywords: | Peptides Potassium Prebiotic chemistry Origin of life |
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