A synthetic host-guest system achieves avidin-biotin affinity by overcoming enthalpy-entropy compensation.
The molecular host cucurbit[7]uril forms an extremely stable inclusion complex with the dicationic ferrocene derivative bis(trimethylammoniomethyl)ferrocene in aqueous solution. The equilibrium association constant for this host-guest pair is 3 x 10(15) M(-1) (K(d) = 3 x 10(-16) M), equivalent to that exhibited by the avidin-biotin pair. Although purely synthetic systems with larger association constants have been reported, the present one is unique because it does not rely on polyvalency. Instead, it achieves its extreme affinity by overcoming the compensatory enthalpy-entropy relationship usually observed in supramolecular complexes. Its disproportionately low entropic cost is traced to extensive host desolvation and to the rigidity of both the host and the guest.
Rekharsky
Mikhail V
MV
ICORP Entropy Control Project (JST) and Department of Applied Chemistry, Osaka University, Yamada-oka, Suita 565-0871, Japan.
Mori
Tadashi
T
Yang
Cheng
C
Ko
Young Ho
YH
Selvapalam
N
N
Kim
Hyunuk
H
Sobransingh
David
D
Kaifer
Angel E
AE
Liu
Simin
S
Isaacs
Lyle
L
Chen
Wei
W
Moghaddam
Sarvin
S
Gilson
Michael K
MK
Kim
Kimoon
K
Inoue
Yoshihisa
Y
D001360:Avidin / Q000737:chemistry*; D001710:Biotin / Q000737:chemistry*; D019921:Biotinylation; D001952:Bridged-Ring Compounds / Q000737:chemistry*; D002151:Calorimetry / Q000379:methods; D002621:Chemistry / Q000379:methods*; D018360:Crystallography, X-Ray / Q000379:methods; D019277:Entropy; D006860:Hydrogen Bonding; D007093:Imidazoles / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D019809:Streptavidin; D013816:Thermodynamics; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
D001360:Avidin; D001710:Biotin; D001952:Bridged-Ring Compounds; D007093:Imidazoles; D019809:Streptavidin; C456276:cucurbit(7)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils