Molecular recognition by natural macrocycles. I. d-tubocurarine as a host molecule for organic anions.
The binding of 8-anilino-1-naphthalenesulfonate and 15 anions of substituted benzoic, aliphatic dicarboxylic, and N-acetyl-alpha-amino acids to a macrocyclic alkaloid d-tubocurarine in aqueous solution has been studied by fluorometry, conductometry, and 1H NMR. The binding constants vary from ca. 50 to 3300 M-1 depending on the guest structure, charge and hydrophobicity. The results of fluorescence and NMR studies show that the host-guest complexation of the anions of aromatic acids involves the formation of a salt bridge between the quaternary nitrogen of the alkaloid and the anionic group of the guest as well as hydrophobic/Van der Waals interactions between the guest and host aromatic moieties. The binding of dianions of aliphatic dicarboxylic acids most probably is purely electrostatic. In general, d-tubocurarine possesses binding ability comparable to that of synthetic cyclophanes. It binds enantiospecifically anions of N-acetyl-alpha-amino acids and discriminates between positional isomers of anions of hydroxy and carboxy substituted benzoic acids.
Alcántar
C G
CG
Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Cuernavaca, México.
Eliseev
A V
AV
Yatsimirsky
A K
AK
D000838:Anions / Q000737:chemistry / Q000378:metabolism*; D001554:Benzene / Q000737:chemistry / Q000378:metabolism; D003217:Conductometry; D005470:Fluorometry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014403:Tubocurarine / Q000737:chemistry* / Q000378:metabolism*
D000838:Anions; D001554:Benzene; D014403:Tubocurarine