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Updated: May 24, 2026

Nuclear Magnetic Resonance Spectroscopy for the Identification of Multiple Phosphorylations of Intrinsically Disordered Proteins
Published on: December 27, 2016
1H NMR spectroscopic identification of protonable sites in cryptolepines with C-11 substituents containing two amino
João Lavrado1, Alexandra Paulo, Elena Bichenkova
1iMed-UL, Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1649-003, Lisbon, Portugal.
Abstract:
Knowledge of protonable sites and acid dissociation constants of cryptolepine derivatives having C-11 substituents containing two amino functionalities is of great importance to the understanding of the mechanism of their antimalarial action, which may contribute to their further development as drug candidates. In this work, we applied (1)H NMR titration to investigate the acid-base characteristics of these polyprotic compounds in the pH range 3-13. We identified three acid-base equilibria with most acid dissociation constants (pK(a)*) being greater than 10.5, which prevented us from using the potentiometric method. Overall, (1)H NMR titration was sensitive and suitable for the determination of pK(a) values for these drug leads.
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