Microscopic protonation constants in tobramycin. An NMR and pH study with the aid of partially N-acetylated derivatives.
Three tetra-N-acetyl derivatives and one tri-N-acetyl derivative of tobramycin (1) have been prepared by partial N-acetylation. Comparison of the pKa values, determined by NMR chemical shift titrations and pH titration of the derivatives, with those of unprotected 1 suggests that protonation equilibria at any particular amino group in 1 are not likely to be influenced by those at other sites. pH-Dependent conformational changes in 1 were assessed on the basis of 1H and 13C chemical shift changes in the derivatives.
Szilágyi
L
L
Department of Organic Chemistry, L. Kossuth University, Debrecen, Hungary.
Pusztahelyi
Z S
ZS
Jakab
S
S
Kovács
I
I
D000107:Acetylation; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008969:Molecular Sequence Data; D009904:Optical Rotation; D013329:Structure-Activity Relationship; D014031:Tobramycin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*
D007202:Indicators and Reagents; D014031:Tobramycin