Highly negative homotropic allosteric binding of viologens in a double-cavity porphyrin.
The synthesis of a double-cavity porphyrin with interesting allosteric binding properties toward viologens (N,N'-disubstituted 4,4'-bipyridines) is described. The porphyrin host forms very strong 1:2 complexes with viologens, displaying a negative allosteric behavior. The first viologen guest binds exceptionally tight (K > 107 M-1), and the second guest binds much more weakly (DeltaDeltaG = 9-15 kJ mol-1). The allosteric effect, one of the highest reported so far, originates in structural changes upon binding the first ligand, closely following the sequential (or induced-fit) theory of allosteric interactions by Koshland, Némethy, and Filmer (the KNF-model).
Thordarson
Pall
P
Department of Organic Chemistry, NSRIM, University of Nijmegen, Toernooiveld 1, 6525 ED, Nijmegen, The Netherlands.
Bijsterveld
Edward J A
EJ
Elemans
Johannes A A W
JA
Kasák
Peter
P
Nolte
Roeland J M
RJ
Rowan
Alan E
AE
D040761:Biomimetic Materials / Q000737:chemistry; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011166:Porphyrins / Q000138:chemical synthesis / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D014755:Viologens / Q000737:chemistry*
D011166:Porphyrins; D014755:Viologens