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2018-01-01

Karmakar, A., Askar, A.M., Bernard, G.M., Terskikh, V.V., Ha, M., Patel, S., Shankar, K., Michaelis, V.K.

synthesis method by redirecting the thermodynamically driven compositions. Moreover, we illustrate the importance of complementary characterization methods, obtaining atomic-scale structural information from multinuclear, multifield, and multidimensional solid-state magnetic resonance spectroscopy, as well

as from quantum chemical calculations and long-range structural details using powder X-ray diffraction. The solvent-free mechanochemical synthesis approach is also compared to traditional solvent synthesis, revealing identical solid-solution behavior; however, the mechanochemical approach offers

superior control over the stoichiometry of the final mixed-halide composition, which is essential for device engineering.

2018-01-01

Askar, A.M., Karmakar, A., Bernard, G.M., Ha, M., Terskikh, V.V., Wiltshire, B.D., Patel, S., Fleet, J., Shankar, K., Michaelis, V.K.

critical to obtaining optimum solar cell performance. Here, we report a solvent-free mechanochemical synthesis (MCS) method to prepare FA-MHPs, starting with their parent compounds (FAPbX3; X = Cl, Br, I), achieving compositions not previously accessible through the solvent synthesis (SS) technique. By

and Br/I MHPs. Our results pave the way for advanced methods in atomic-level structural understanding while offering a one-pot synthetic approach to prepare MHPs with superior control of stoichiometry.

2019-01-31

Xiaochao Xue, Ruixiang Blake Zheng, Akihiko Koizumi, Ling Han, John S. Klassen, Todd L. Lowary

Mycobacteria, including the human pathogen Mycobacterium tuberculosis, produce a complex cell wall that is critical for their survival. The largest structural component of the cell wall, the mycolylarabinogalactanpeptidoglycan complex, has at its core a galactan domain composed of D

-galactofuranose residues. Mycobacterial galactan biosynthesis has been proposed to involve two glycosyltransferases, GlfT1 and GlfT2, which elongate polyprenol-pyrophosphate linked glycosyl acceptor substrates using UDP-galactofuranose as the donor substrate. We here report the first chemical synthesis of GlfT1

and demonstrate a straightforward route for the preparation of such compounds. The work also provides additional support for the process by which this important glycan is biosynthesized using, for the first time, close structural analogs to the natural substrates.

2018-01-16

Hunter, Carmanah D, Khanna, Neha, Richards, Michele R, Darestani, Reza Rezaei, Zou, Chunxia, Klassen, John S, Cairo, Christopher W.

Recognition of terminal sialic acids is central to many cellular processes, and structural modification of sialic acid can disrupt these interactions. A prominent, naturally occuring, modification of sialic acid is 9-O-acetylation (9-O-Ac). Study of this modification through generation and analysis

-acetylation, and C-5 group (Neu5Gc). Relative rates of substrate cleavage by hNEU were determined using fluorescence spectroscopy and electrospray ionization mass spectrometry. We report that 9-O-acetylation had a significant, and differential, impact on sialic acid hydrolysis by hNEU with general substrate

aglycone. The impact of these minor structural changes to sialic acid on hNEU activity was unexpected, and these results provide evidence of the substantial influence of 9-O-Ac modifications on hNEU enzyme substrate specificity. Furthermore, these findings may implicate hNEU in processes governed by 9-O

2020-01-01

Ha, M., Karmakar, A., Bernard, G.M., Basilio, E., Krishnamurthy, A., Askar, A.M., Shankar, K., Kroeker, S., Michaelis, V.K.

further related to the measured chemical shift anisotropy present when Sn deviates from octahedral symmetry. We also discuss the rapid degradation of pristine MASnI3 over 2 days studied using in situ119Sn NMR spectroscopy. Finally, we report on the 1H, 13C, 119Sn, and 207Pb NMR structural properties of a

2009

Abbott, D. W., Boraston, Alisdair B. , Vocadlo, David J., Macauley, Matthew S.

we describe mechanistic and structural studies of the catalytic domain (SpGH85) of Endo-D that provide compelling support for GH85 enzymes using a catalytic mechanism involving substrate-assisted catalysis. Furthermore, the structure of SpGH85 in complex with the mechanism-based competitive inhibitor

kinetic studies, suggests these enzymes may use an unusual proton shuttle to coordinate effective general acid and base catalysis to aid cleavage of the glycosidic bond. These results collectively provide a blueprint that may be used to facilitate protein engineering of these enzymes to improve their