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STD NMR
6 |4 W/ H2 e! L( a; r+ ^' U. dSTD NMR
2 h) F7 V' T8 O- Y7 c experiments detect magnetization that is transferred from a receptor protein
" v+ Z8 u2 t* _1 D' {& ^, k& X to a bound ligand. Only bound ligands show STD effects. The experiment may be
, s1 V, I* R; Y6 |2 h combined with virtually any other NMR experiment, and therefore is well suitable
- \) ?" [0 G) j$ M" y7 w to tackle even very complex problems. In particular, in combination with multidimensional
Y! v1 s2 e; A+ f: v: d3 S NMR a full characterization of a bound ligand out of a mixture is straightforward.
! M1 u2 S6 O) m+ a2 N* u; i5 d) N STD NMR is extremely robust and gives maximal effects at protein to ligand ratios
2 ^) G; V, k7 ^# \ greater than ca. 1:100. It follows that less than 1 nmol of protein is necessary
7 C! N" M0 N1 Z0 J$ q8 F: q for screening. With the availability of so called cryo probes it will be possible
1 \9 R) c4 F$ ^1 [# ? K: e to work with hundred pmol amounts of protein. The dissociation constant should 6 K; r+ A: `4 x( M
be in the range between nM and mM. Therefore, STD NMR covers at least two orders ! x4 Y8 e- `9 j4 G8 G
of magnitudes more for dissociation constants than trNOE experiments. From competitive 7 [+ C: D; y1 [; k& j) }
STD experiments dissociation constants may be derived. |7 {6 `" c2 i0 S8 E
! r& r( X4 Z3 x i8 S& T# S
8 b* ~ y+ a/ `0 X! Z
Schematic
2 P" W0 y6 W* O8 s5 O6 h$ b display of the STD NMR effect. Saturation of the protein leads to a direct saturation ) o+ z: F7 r J: r$ b0 N e
of those parts of ligand(s) in direct contact to the protein. By exchange between ; Z7 ?1 m8 W1 D% u
bound and free state the saturation is transported to solution and detected
6 Z- H* r4 s+ G) h by subtracting a spectrum with saturation from a normal spectrum.
9 V& x& q- o* D/ H5 b' y
STD NMR gives precise information about the binding epitope of the ligand. This : b. |! Y4 y3 p% j7 {
is very important information for the design of a potent drug. The optimal drug 2 z- \# ]) X% d
is of optimal size and optimal shape. The size is deduced from STD NMR, and $ k+ {4 k( [. G" o( ~3 @7 }
the shape is delivered by trNOE experiments.
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发表于 2010-10-18 18:42:26
