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1. Conformational disorder in the crystal structure of methyl 2-acetamido-2-deoxy-β- D -glucopyranosyl-(1→4)–2-acetamido-2-deoxy-β- D -glucopyranoside (methyl β-chitobioside) methanol monosolvate

   https://doi.org/10.1107/S2053229624005199  

   Shit, Pradip ; Tetrault, Timothy ; Zhang, Wenhui ; Yoon, Mi-Kyung ; Oliver, Allen G ; Serianni, Anthony S ( July 2024 , Acta Crystallographica Section C Structural Chemistry)

   Methyl 2-acetamido-2-deoxy-β-D-glucopyranosyl-(1→4)-2-acetamido-2-deoxy-β-D-glucopyranoside (methyl β-chitobioside), (IV), crystallizes from aqueous methanol at room temperature to give a structure (C₁₇H₃₀N₂O₂₂·CH₃OH) containing conformational disorder in the exocyclic hydroxymethyl group of one of its βGlcNAc residues. As observed in other X-ray structures of disaccharides containing β-(1→4)O-glycosidic linkages, inter-residue hydrogen bonding between O3H of the βGlcNAc bearing the OCH₃aglycone and O5 of the adjacent βGlcNAc is observed based on the 2.79 Å internuclear distance between the O atoms. The structure of (IV) was compared to that determined previously for 2-acetamido-2-deoxy-β-D-glucopyranosyl-(1→4)-2-acetamido-2-deoxy-β-D-glucopyranose (β-chitobiose), (III). TheO-glycosidic linkage torsion angles,phi(ϕ) andpsi(ψ), in (III) and (IV) differ by 6–8°. TheN-acetyl side chain conformation in (III) and (IV) shows some context dependence, with the C1—C2—N—C_cartorsion angle 10–15° smaller for the βGlcNAc residue involved in the internalO-glycosidic linkage. In (IV), conformational disorder is observed in the exocyclic hydroxymethyl (–CH₂OH) group in the βGlcNAc residue bearing the OCH₃aglycone, and a fitting of the electron density indicates an approximate 50:50 distribution of thegauche–gauche(gg) andgauche–trans(gt) conformers in the lattice. Similar behavior is not observed in (III), presumably due to the different packing structure in the vicinity of the –CH₂OH substituent that affects its ability to hydrogen bond to proximal donors/acceptors. Unlike (IV), a re-examination of the previously reported electron density of (III) revealed conformational disorder in theN-acetyl side chain attached to the reducing-end βGlcNAc residue caused by rotation about the C2—N bond.

    

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2. Phenanthroline-Catalyzed Stereoselective Formation of α-1,2- cis 2-Deoxy-2-Fluoro Glycosides

   https://doi.org/10.1021/acscatal.0c04381  

   DeMent, Paul M. ; Liu, Chenlu ; Wakpal, Joseph ; Schaugaard, Richard N. ; Schlegel, H. Bernhard ; Nguyen, Hien M. ( February 2021 , ACS Catalysis)

   null (Ed.)
3. Organometallic Nucleosides: Synthesis and Biological Evaluation of Substituted Dicobalt Hexacarbonyl 2′-Deoxy-5-oxopropynyluridines

   https://doi.org/10.1002/open.201700168  

   Kaczmarek, Renata ; Korczyński, Dariusz ; Królewska-Golińska, Karolina ; Wheeler, Kraig A. ; Chavez, Ferman A. ; Mikus, Agnieszka ; Dembinski, Roman ( March 2018 , ChemistryOpen)
4. Myosin dynamics during relaxation in mouse soleus muscle and modulation by 2′‐deoxy‐ATP

   https://doi.org/10.1113/JP280402  

   Ma, Weikang ; Childers, Matthew ; Murray, Jason ; Moussavi‐Harami, Farid ; Gong, Henry ; Weiss, Robert ; Daggett, Valerie ; Irving, Thomas ; Regnier, Michael ( September 2020 , The Journal of Physiology)

   Skeletal muscle relaxation has been primarily studied by assessing the kinetics of force decay. Little is known about the resultant dynamics of structural changes in myosin heads during relaxation.

   The naturally occurring nucleotide 2‐deoxy‐ATP (dATP) is a myosin activator that enhances cross‐bridge binding and kinetics.

   X‐ray diffraction data indicate that with elevated dATP, myosin heads were extended closer to actin in relaxed muscle and myosin heads return to an ordered, resting state after contraction more quickly.

   Molecular dynamics simulations of post‐powerstroke myosin suggest that dATP induces structural changes in myosin heads that increase the surface area of the actin‐binding regions promoting myosin interaction with actin, which could explain the observed delays in the onset of relaxation.

   This study of the dATP‐induced changes in myosin may be instructive for determining the structural changes desired for other potential myosin‐targeted molecular compounds to treat muscle diseases.

   Here we used time‐resolved small‐angle X‐ray diffraction coupled with force measurements to study the structural changes in FVB mouse skeletal muscle sarcomeres during relaxation after tetanus contraction. To estimate the rate of myosin deactivation, we followed the rate of the intensity recovery of the first‐order myosin layer line (MLL1) and restoration of the resting spacing of the third and sixth order of meridional reflection (S_M3and S_M6) following tetanic contraction. A transgenic mouse model with elevated skeletal muscle 2‐deoxy‐ATP (dATP) was used to study how myosin activators may affect soleus muscle relaxation. X‐ray diffraction evidence indicates that with elevated dATP, myosin heads were extended closer to actin in resting muscle. Following contraction, there is a slight but significant delay in the decay of force relative to WT muscle while the return of myosin heads to an ordered resting state was initially slower, then became more rapid than in WT muscle. Molecular dynamics simulations of post‐powerstroke myosin suggest that dATP induces structural changes in myosin that increase the surface area of the actin‐binding regions, promoting myosin interaction with actin. With dATP, myosin heads may remain in an activated state near the thin filaments following relaxation, accounting for the delay in force decay and the initial delay in recovery of resting head configuration, and this could facilitate subsequent contractions.

    

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5. An Improved Approach to the Direct Construction of 2-Deoxy-β-Linked Sugars: Applications to Oligosaccharide Synthesis

   https://doi.org/10.1002/chem.201800736  

   Lloyd, Dina ; Bennett, Clay S. ( May 2018 , Chemistry - A European Journal)