Abstract LB-01: EMERGENCY TRACHEOSTOMY CASE DUE TO TRACHEAL STENOSIS ON CHILDREN AGE 12 YEARS 9 MONTHS

X-ray Crystal Structures of the Influenza M2 Proton Channel Drug-Resistant V27A Mutant Bound to a Spiro-Adamantyl Amine Inhibitor Reveal the Mechanism of Adamantane Resistance

“…In these NMR structures, the TM helix ends and the turn / disordered region begins at either residue Leu46 (2KWX, 2RLF, 2KIH) 62,67,68 or residue Phe48 (2L0J, 2N70). 69,70 The conformation of the channel's C-terminus that we observe in the X-ray crystal structure here differs from solution and solid state NMR structures. Solution NMR studies have shown that the conformation of the juxta-membrane domain connecting the TM and cytosolic helices is sensitive to solubilizing environments.…”

High-Sensitivity Detection of Nanometer 1H–19F Distances for Protein Structure Determination by 1H-Detected Fast MAS NMR

“…To determine the three-dimensional fold and oligomeric structure of proteins and macromolecular assemblies, distances in the 1-2 nm range are crucial 2 . When 13 C- 13 C and 13 C- 15 N distances are measured, as in most NMR structural determination studies 1 , the distance restraints are typically limited to ~7 Å or less due to the low gyromagnetic ratios of 13 C and 15 N spins. Longer distance restraints of ~10 Å can be measured when dipolar couplings between different nuclear spins with higher gyromagnetic ratios such as 19 F and 31 P [3][4][5] are recoupled under MAS using the rotational-echo double-resonance (REDOR) technique 6 .…”

“…The choice of 1 H- 19 F heteronuclear distance measurement circumvents the difficulties in measuring homonuclear 1 H-1 H distances, where the dense 1 H network in biomolecules causes dipolar truncation 7 and relayed transfer [8][9] . Proton dilution by perdeuteration followed by back H/D exchange 10 still leaves uncertainties in 1 H-1 H distance measurements due to residual relayed polarization transfer, while ultrafast MAS of ~100 kHz for protonated samples [11][12][13][14][15] requires 3D and 4D correlation experiments for 1 H chemical shift assignment [16][17][18] . The 1 H- 19 F distance approach demonstrated here circumvents these difficulties, and complements the recently introduced homonuclear 19 F- 19 F distance measurements [19][20][21] .…”

“…The difference spectrum (ΔS) between the two shows the amide protons that are close to the 19 F spin. We demonstrate this technique using 13 C, 15 N, 2 H-labeled GB1 that contains a single fluorinated residue, 5-19 F-Trp43 (5F-W43 CDN-GB1). The protein was fully back-exchanged in H 2 O to obtain amide protons.…”

“…Similar to all 1 Hdetected fast MAS experiments, the key requirement for multiplexed 1 H- 19 F distance measurement is sufficient resolution of the 1 H and 15 N chemical shifts in the 2D spectra. This 1 H- 19 F distance technique is complementary to the recently introduced 13 C- 13 C resolved 13 C- 19 F distance experiment 22 , and yields more distance restraints than 19 F- 19 F 2D experiments [20][21] . Aromatic residues in proteins, particularly the sparse tryptophan (Trp) residues, can be fluorinated during protein expression without perturbing the structure [31][32] .…”