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STD NMR + k5 q/ y5 y2 y$ K. m3 w
STD NMR
( L. U+ h$ ?; A, w% {5 d experiments detect magnetization that is transferred from a receptor protein
+ k. \# ]# p1 R# T to a bound ligand. Only bound ligands show STD effects. The experiment may be
}; l6 n p0 t+ j$ u combined with virtually any other NMR experiment, and therefore is well suitable
/ `* e! ?; t) v( f* P to tackle even very complex problems. In particular, in combination with multidimensional
& B! H9 ~6 |" A9 N( k NMR a full characterization of a bound ligand out of a mixture is straightforward.
$ x/ `, b7 l* S' c. G+ ? STD NMR is extremely robust and gives maximal effects at protein to ligand ratios
: b' B1 L: F/ j) J greater than ca. 1:100. It follows that less than 1 nmol of protein is necessary # w7 p' [" Q) k; g0 W% s
for screening. With the availability of so called cryo probes it will be possible ' G9 A; l# z' ?' Q& q0 ?4 J4 Z4 X0 Q
to work with hundred pmol amounts of protein. The dissociation constant should
3 T0 s" j6 ^; g5 x; z be in the range between nM and mM. Therefore, STD NMR covers at least two orders
- n7 U4 i+ H2 h of magnitudes more for dissociation constants than trNOE experiments. From competitive ( W' i- ^" U; q! k
STD experiments dissociation constants may be derived.
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# r" Z- C/ C9 N a1 c% c" J. D Schematic
' n8 _/ o; ]5 K2 O4 Q display of the STD NMR effect. Saturation of the protein leads to a direct saturation + P" a7 [/ N4 Q, ~* E5 O6 v+ Q- ~
of those parts of ligand(s) in direct contact to the protein. By exchange between ) q5 i2 j9 T, o$ z a1 B' Y" s
bound and free state the saturation is transported to solution and detected . V$ V* ^5 A9 x/ C8 e# d
by subtracting a spectrum with saturation from a normal spectrum.
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STD NMR gives precise information about the binding epitope of the ligand. This
1 |( G; V+ ?& a/ `# v" {8 ~ is very important information for the design of a potent drug. The optimal drug 6 @# K) }9 M. z
is of optimal size and optimal shape. The size is deduced from STD NMR, and @1 ~9 v3 p* n8 h
the shape is delivered by trNOE experiments.
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发表于 2010-10-18 18:42:26
