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STD NMR
) {. ]) t8 a k6 rSTD NMR
/ [7 V4 X) R6 a& R3 K# f/ u experiments detect magnetization that is transferred from a receptor protein ; H2 u/ r+ I$ U9 g
to a bound ligand. Only bound ligands show STD effects. The experiment may be
( x+ F" F$ r0 H6 L1 g, | combined with virtually any other NMR experiment, and therefore is well suitable
& e2 p2 y8 u7 N- D1 @2 }5 d! i/ G! z% K6 ` to tackle even very complex problems. In particular, in combination with multidimensional
4 g9 m) b2 L( V$ e& T NMR a full characterization of a bound ligand out of a mixture is straightforward. . J* A% T& Q5 l+ ^
STD NMR is extremely robust and gives maximal effects at protein to ligand ratios & j% t5 k( \( _5 z
greater than ca. 1:100. It follows that less than 1 nmol of protein is necessary ( F8 _' Q/ M5 h! G4 `
for screening. With the availability of so called cryo probes it will be possible 7 o& w& W1 | o% u
to work with hundred pmol amounts of protein. The dissociation constant should 1 t% O4 f, c( X3 {1 q; a
be in the range between nM and mM. Therefore, STD NMR covers at least two orders 3 ~9 f% V/ S' U' {
of magnitudes more for dissociation constants than trNOE experiments. From competitive
! m9 k' z4 [( x# g) f STD experiments dissociation constants may be derived.
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Schematic
+ V4 i! P, Y& K0 I7 r( j" _" e* M4 d display of the STD NMR effect. Saturation of the protein leads to a direct saturation
4 b% P- }# i! c) n" _3 S7 K' p% c* n of those parts of ligand(s) in direct contact to the protein. By exchange between
H2 D& F z# f! m& o9 W bound and free state the saturation is transported to solution and detected
) H& M( X! k/ S) r: } by subtracting a spectrum with saturation from a normal spectrum.
$ W' D% f% ^0 N3 {1 k- @7 R5 m7 \ STD NMR gives precise information about the binding epitope of the ligand. This 3 V% }4 E* y+ ~6 P' E+ s7 x
is very important information for the design of a potent drug. The optimal drug
: v7 o2 H# l0 E1 d+ L is of optimal size and optimal shape. The size is deduced from STD NMR, and # c7 R5 S E) j1 u3 n
the shape is delivered by trNOE experiments.
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发表于 2010-10-18 18:42:26
