Asim K. Bera

TL;DR: The key finding of the study is a conserved site of a water molecule near oxyanion hole of the enzyme active site, which is found in all the modeled complexes and in most crystal structures of papain family either native or complexed.

TL;DR: Results of the investigation by computer-assisted molecular modeling structurally demonstrate why model-2 would be more applicable to the static x-ray structure of the complex at physiological pH than model-1, and can be used for metabolic screening of NSAIDs.

Abstract: The crystal structure of a unidecahydrated co-complex between two Inosine 5′-monophosphate (IMP) and one L-glutamine has been determined at atomic resolution by X-ray crystallographic methods. The crystal belongs to the monoclinic space group P21 with cell dimensions a = 8.690(2), b = 21.900(3), c = 12.370(1) A, and β = 110.59(3)°. This structure reveals the recognition mechanism of glutamine to the nucleotide through direct and water-mediated hydrogen bonds. The phosphate oxygen (O23) seems to prefer the nonspecific interaction with the functional sites of glutamine (NA· · ·O23 = 2.672, OH· · ·O23 = 3.063, OE· · ·O23 = 3.104 A), whereas the bases prefer specific (N23· · ·O = 2.874 A) bindings. But here no specific interaction has been observed at N17 and N27, which were observed in serine—IMP complex. However, the solvent mediated N17· · ·OW3· · ·N27 hydrogen bonds for stabilization of the stacked purine bases have been observed as in other aminoacid-nucleotide cocrystals. The striking habit of glutamine to occupy the nearly same region of the nucleotide cocrystal as was found in the serine—IMP complex through substantial replacement of free and bound water molecules, shows certainly the cooperative hydrogen bonding economy of water molecules.

TL;DR: The crystal structure of an octadecahydrated complex between two inosine 5′-monophosphate (IMP) has been determined at atomic resolution, which reveals the hydrogen bonding and the coordination cooperativity of water molecules to nucleotide recognition as discussed by the authors.

TL;DR: An attempt has been made to clarify the understanding of the occurrence, organisation and possible interaction of the diverse lipids present in the mycobacterial cell wall and their possible structure and function.