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PMC:7594251 / 52619-56266 JSONTXT 7 Projects

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Id Subject Object Predicate Lexical cue
T361 0-6 Sentence denotes 3.1.4.
T362 7-57 Sentence denotes Transferred NOE (tr-NOE) in Ligand Based Screening
T363 58-156 Sentence denotes The application of the transferred NOE (Tr-NOE) effect was first demonstrated by Bothner-By [282].
T364 157-318 Sentence denotes The Tr-NOE is the nuclear Overhauser effect between ligand spins, which are in chemical exchange between the bound and unbound form with the protein or receptor.
T365 319-407 Sentence denotes Ligands, which are a mixture of target molecules, are small in size (below 500–1000 Da).
T366 408-588 Sentence denotes Since they are usually low molecular weight molecules, they exhibit much shorter correlation times when compared to the receptor and have slow NOE build-ups with no spin diffusion.
T367 589-655 Sentence denotes This is the reason they show small positive NOEs in the free form.
T368 656-808 Sentence denotes When binding to a protein receptor, the situation changes, where the ligand acquires large correlation times in the bound state with rapid NOE build-up.
T369 809-902 Sentence denotes Then they show spin diffusion and a strong negative NOE, which is termed the transferred NOE.
T370 903-1073 Sentence denotes Signals arising from the protein are usually not observed for large proteins as they are generally kept low in concentration, with ligands in a high excess concentration.
T371 1074-1165 Sentence denotes In addition, most of the time protein signals are suppressed by their very short T2 period.
T372 1166-1534 Sentence denotes It is worthwhile to mention that ligands that are in fast exchange between the bound and the free form (dissociation constants ranging from μM to mM) get enough bound time to transfer the negative NOE from the protein complex to the population of the free molecules, yet usually retain the chemical shift of the free molecule along with the relaxation characteristics.
T373 1535-1719 Sentence denotes In order to observe tr-NOEs, the following condition have to be fulfilled:(3) |Nb∂b|≫|Nf∂f| where N and ∂ represent the number of molecules and the cross-relaxation rate, respectively.
T374 1720-1790 Sentence denotes The subscript b and f represent the bound and free form, respectively.
T375 1791-1892 Sentence denotes Therefore, to observe the tr-NOEs, a high excess concentration of ligands over protein is maintained.
T376 1893-2171 Sentence denotes On the other hand, if the ligand concentration is kept too high, the excess free ligand in solution will exhibit positive NOE, which can result in a significant reduction of the tr-NOESY enhancements due to negative NOE developed by the very small concentration of bound ligand.
T377 2172-2329 Sentence denotes Hence, the preparation of the sample becomes tricky and an optimum ratio between 10–30 to 1 is maintained while considering the dissociation constant values.
T378 2330-2444 Sentence denotes The binding of a ligand to a receptor protein can easily be identified by observing the sign and size of the NOEs.
T379 2445-2612 Sentence denotes There are some distinct experimental features for the discrimination between tr-NOEs from the bound state and NOEs of the ligand in free states like the build-up rate.
T380 2613-2708 Sentence denotes For tr-NOEs, this is in the range of 50 to 100 ms, whereas for small ligands it is much longer.
T381 2709-2837 Sentence denotes There have been various instances of experimental implementations to quickly determine the binding activity of ligand libraries.
T382 2838-3001 Sentence denotes One example was to find the ligand molecule among a library of 10 similar structure polysaccharides that is bioactive in binding with recombinant E-selectin [283].
T383 3002-3087 Sentence denotes This is a protein present in an IgG chimera with a molecular weight of about 220 kDa.
T384 3088-3137 Sentence denotes In this case, two 2D NOESY spectra were recorded.
T385 3138-3390 Sentence denotes The NOESY spectra for the ligand library was measured at several temperatures and it was found that most of the 10 compounds exhibited the weak positive NOEs at 310 K, which was then chosen to differentiate between trNOEs showing large negative values.
T386 3391-3543 Sentence denotes The trNOESY spectra of the ligand library in the presence of protein was recorded at different ratios, such as 5:1, 8:1, 12:1, 15:1, and 20:1, at 310 K.
T387 3544-3647 Sentence denotes In all the ratios, trNOEs were observed; however, the ratio of 15:1 represented the best-case scenario.