(Strept)avidin as host for biotinylated coordination complexes: stability, chiral discrimination, and cooperativity.
Incorporation of a biotinylated ruthenium tris(bipyridine) [Ru(bpy)(2)(Biot-bpy)](2+) (1) in either avidin or streptavidin-(strept)avidin-can be conveniently followed by circular dichroism spectroscopy. To determine the stepwise association constants, cooperativity, and chiral discrimination properties, diastereopure (Lambda and Delta)-1 species were synthesized and incorporated in tetrameric (strept)avidin to afford (Delta-[Ru(bpy)(2)(Biot-bpy)](2+))(x)() subsetavidin, (Lambda-[Ru(bpy)(2)(Biot-bpy)](2+))(x)() subsetavidin, (Delta-[Ru(bpy)(2)(Biot-bpy)](2+))(x)() subsetstreptavidin, and (Lambda-[Ru(bpy)(2)(Biot-bpy)](2+))(x)() subsetstreptavidin (x = 1-4) For these four systems, the overall stability constants are log beta(4) = 28.6, 30.3, 36.2, and 36.4, respectively. Critical analysis of the CD titrations data suggests a strong cooperativity between the first and the second binding event (x = 1, 2) and a pronounced difference in affinity between avidin and streptavidin for the dicationic guest 1 as well as modest enantiodiscrimination properties with avidin as host.
Loosli
Andreas
A
Institute of Chemistry, University of Neuchâtel, Av. Bellevaux 51, CP 2, CH-2007 Neuchâtel, Switzerland.
Rusbandi
Untung Edy
UE
Gradinaru
Julieta
J
Bernauer
Klaus
K
Schlaepfer
Carl Wilhelm
CW
Meyer
Michel
M
Mazurek
Sylwester
S
Novic
Marjana
M
Ward
Thomas R
TR
D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000737:chemistry; D001360:Avidin / Q000737:chemistry; D001426:Bacterial Proteins / Q000138:chemical synthesis / Q000737:chemistry*; D001710:Biotin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D019921:Biotinylation; D056831:Coordination Complexes; D015394:Molecular Structure; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D019809:Streptavidin / Q000737:chemistry*; D013329:Structure-Activity Relationship; D017975:Ruthenium Compounds
D015082:2,2'-Dipyridyl; D001360:Avidin; D001426:Bacterial Proteins; D001710:Biotin; D056831:Coordination Complexes; D019809:Streptavidin; C066114:biotin-streptavidin complex; C547232:tris(2,2-bipyridine)-ruthenium(II); D017975:Ruthenium Compounds