Antivitamin B12 Inhibition of the Human B12-Processing Enzyme CblC: Crystal Structure of an Inactive Ternary Complex with Glutathione as the Cosubstrate

B₁₂ antivitamins are important and robust tools for investigating the biological roles of vitamin B₁₂. Here, the potential antivitamin B₁₂ 2,4-difluorophenylethynylcobalamin (F2PhEtyCbl) was prepared, and its 3D structure was studied in solution and in the crystal. Chemically inert F2PhEtyCbl resisted thermolysis of its Co−C bond at 100 °C, was stable in bright daylight, and also remained intact upon prolonged storage in aqueous solution at room temperature. It binds to the human B₁₂-processing enzyme CblC with high affinity (K_D=130 nm ) in the presence of the cosubstrate glutathione (GSH). F2PhEtyCbl withstood tailoring by CblC, and it also stabilized the ternary complex with GSH. The crystal structure of this inactivated assembly provides first insight into the binding interactions between an antivitamin B₁₂ and CblC, as well as into the organization of GSH and a base-off cobalamin in the active site of this enzyme.     

Synthesis and Characterization of 2-Aminobenzothiazol and 1-Methylisatin Co-Сrystal

Crystallography Reports - A co-crystal of 2-aminobenzothiazol and 1-methylisatin (III) was synthesized and characterized by elemental analysis, Fourier-transform infrared spectroscopy, nuclear...     

Global dynamics of a Holling Type-III two prey–one predator discrete model with optimal harvest strategy

Nonlinear Dynamics - This paper deals with a discrete-time two prey–one predator system with Holling Type-III functional response, along with inter-specific competition between the prey and...     

Novel radioassay for anti-thyroperoxidase autoantibodies using protein A coupled magnetizable cellulose particles as an immunoadsorbent

Journal of Radioanalytical and Nuclear Chemistry - Autoantibodies against thyroid peroxidase (TPO); described initially as thyroid microsomal antigen, are found in most of the patients with...     

A metal-free iodine-mediated conversion of hydroxamates to esters

Abstract

A metal-, oxidant-, and additive-free conversion of hydroxamates to esters have been achieved using molecular iodine as the reagent using a novel but not-so-explored heron-type rearrangement. The reaction proceeds with almost equal facility with substrates having either electron-donating or electron-withdrawing substituent. Similarly, α,ß-unsaturated, and sterically hindered ortho-substituted hydroxamates also undergo the desired transformation smoothly.     

Heterometallic chalcogenido clusters containing lanthanides and main group metals: emissive precursors to ternary solid-state compounds

Heterometallic clusters containing lanthanides and the group 12 metals can be isolated as crystalline compounds in high yields. These products [(py)8Ln4M2Se6(SePh)4 (Ln = Er, Yb, Lu; M = Cd, Hg)] adopt a double cubane structure with the covalent M occupying an opposing pair of external metal sites. Both Er/M compounds are strongly emissive materials, with emission lifetimes of 1.41 ms (Er/Cd) and 0.71 ms (Er/Hg) and with the Er/Cd radiative quantum efficiency twice that of the Er/Hg compound. Thermal decomposition of the Er/Cd and Yb/Cd compounds at 650 degrees C give the ternary solid-state materials CdLn2Se4.     

Spark-induced agglomeration of aqueous polymeric suspensions

Discharging a high-energy spark underwater creates a shock wave that dissipates through an acoustic field. Colloidal acrylate polymers suspended in water containing dissolved calcium are agglomerated as a result. The degree of agglomeration increases with the number of sparks applied and with increasing calcium content. The calcium decreases the charge on the colloidal particles and thereby increases their propensity to be agglomerated by the acoustic wave. These observations are confirmed in full-scale trials in paper recycling mills where sparking improves the efficiency of centrifugal cleaners by increasing the particle size of the contaminants.     

Synthesis and stereoselective glycosylation of D- and L-glycero-beta-D-manno-heptopyranoses

[reaction: see text] A method for the direct stereocontrolled synthesis of D- and L-glycero-beta-D-manno-heptopyranosides such as those found in the repeating unit of the O-specific polysaccharide from the CNCTC 113/92 LPS (serotype 54) is described. The method relies on the presence of a 4,6-O-benzylidene acetal to effect stereocontrol at the anomeric center; the configuration at C6 (L- or D-glycero) is of minimal importance.     

"Uncorking" of liposomes by matrix metalloproteinase-9

A triggered release methodology of liposomal contents via the enzyme MMP-9 is described.