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STD NMR . i# t* d8 `. M: a3 }) d
STD NMR
! S( U/ @7 k8 v experiments detect magnetization that is transferred from a receptor protein
+ W/ I! p q0 t+ r to a bound ligand. Only bound ligands show STD effects. The experiment may be
4 u& H; x" ^; m! ]$ ~ combined with virtually any other NMR experiment, and therefore is well suitable $ ~% u2 v+ Y5 \
to tackle even very complex problems. In particular, in combination with multidimensional
1 M" V' v9 S1 j1 y6 {) C/ N NMR a full characterization of a bound ligand out of a mixture is straightforward.
+ _, W7 k0 z4 ? STD NMR is extremely robust and gives maximal effects at protein to ligand ratios
$ I! @, M& J( r9 S greater than ca. 1:100. It follows that less than 1 nmol of protein is necessary * y8 {' t! {5 ]7 z4 o( I/ R4 Y0 b
for screening. With the availability of so called cryo probes it will be possible
+ {! t9 k) ^* g to work with hundred pmol amounts of protein. The dissociation constant should
& j6 y" q" E- _# Z: A, F be in the range between nM and mM. Therefore, STD NMR covers at least two orders 8 @ H6 s. n! T; y5 p5 j* }
of magnitudes more for dissociation constants than trNOE experiments. From competitive - F- t$ M/ g/ S
STD experiments dissociation constants may be derived.
3 d- V4 c8 U% n. ]2 o
1 X: u8 A2 _2 h/ y
/ k3 @2 N( H9 k1 d Schematic : v3 e3 \1 ?2 h
display of the STD NMR effect. Saturation of the protein leads to a direct saturation 7 Y( P5 d; P% ?
of those parts of ligand(s) in direct contact to the protein. By exchange between
/ f6 \; a! Z: r bound and free state the saturation is transported to solution and detected ( O% L m* T' m- r
by subtracting a spectrum with saturation from a normal spectrum.
4 r$ @7 u( r5 d }: N- W( {7 X( z# H; `
STD NMR gives precise information about the binding epitope of the ligand. This ; b) k4 Q8 d! i+ C+ H
is very important information for the design of a potent drug. The optimal drug ' p9 b' F: r- H0 v1 s- n( M
is of optimal size and optimal shape. The size is deduced from STD NMR, and
F# r$ y P& l9 n8 N the shape is delivered by trNOE experiments.
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发表于 2010-10-18 18:42:26
