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Recognition of Adenine-like Rings by the Abrin—A Binding Site: A Flexible Docking Approach
Published in Devrim Balköse, Ana Cristina Faria Ribeiro, A. K. Haghi, Suresh C. Ameta, Tanmoy Chakraborty, Chemical Science and Engineering Technology, 2019
Ashima Bagaria, Mukesh Saran, Jagdish Parihar
The pterin-like compounds are poorly soluble. So like in Ricin, search was done for guanine-like compounds29for Abrin-a. The chemical name of the above two compounds are 2-amino-3,4-dihydroxy-4-oxo-7H-pyrrole [2,3-d]-pyrimidine (7DG) and 2-amino-3,4-dihydroxy-4-oxo-9H-pyrrole [2,3-d]-pyrimidine (9DG) and MOG, respectively. These three compounds were found to be stacked between Tyr74 and Tyr113, and the stability is attributed to strong hydrogen bonds and hydrophobic contacts. The SC index has a high value thereby showing affinity of 7DG and 9DG for binding at the active site of Abrin-a (Table 10.6). The SC index for MOG is less compared to 7DG and 9DG (Table 10.6). For these compounds, very few interactions are seen with the protein molecule. The guanine ring makes hydrogen bonds with Arg167, Glu164, and Val75. Figures 10.5–10.7 show the stereo-view of the binding modes of 7DG, 9DG, and MOG. From Table 10.3, it is clear that these ligands fulfill the criterion for Lipinski rule of five.
Uptake, translocation, and metabolism of sulfamethazine by Arabidopsis thaliana: distinguishing between phytometabolites and abiotic transformation products in the media
Published in International Journal of Phytoremediation, 2020
As structural analogs to p-aminobenzoic acid, sulfonamides act as competitive substrates for dihydropteroate synthase, thereby impairing folate synthesis and forming pterin-sulfonamide conjugates (Zhang et al.2012). Conjugation of sulfonamides with pterin has been observed in microorganisms (Achermann et al.2018), phytoplankton (Stravs et al.2017), and A. thaliana (Huynh and Reinhold 2019). Formation of pterin-SMT in A. thaliana plant tissues potentially reduced the plant folate pool size, as previously reported (Zhang et al.2012). Based on the detection of pterin-SMT only in planted reactors (Figure 2), formation of the pterin-SMT conjugate was attributed to phytometabolism.
The role of hydrogen bonds in the mesomorphic behaviour of supramolecular assemblies organized in dendritic architectures
Published in Liquid Crystals Reviews, 2019
Michael Arkas, I. Kitsou, A. Gkouma, M. Papageorgiou
An attempt to force dimerization in a similar biomimetic approach (Figure 27), by replacing pterin ring by a 3–10 carbon atoms spacer, produced a series of glutamic acid dendritic peptides functionalized by undecyl benzalo lipophilic segments [148]. Chiral hexagonal phases (p6 mm) were observed only for the decyl spacer whereas chiral columnar rectangular (p2gg, c2 mm) were obtained for shorter analogs. The stability of these mesophases was again directly correlated to the extent of the intra and intermolecular hydrogen bonds of the peptide groups.
Modelling of growth kinetics of isolated Pseudomonas sp. and optimisation of parameters for enhancement of xanthine oxidoreductase production by statistical design of experiments
Published in Journal of Environmental Science and Health, Part A, 2019
Xanthine oxidoreductase (XOR) is an iron-sulphur containing metalloflavoprotein that catalyses the hydroxylation of purine, pyrimidine, pterin, pteridine and aldehydes.[1] NAD+ dependent Xanthine dehydrogenase (XDH, D-form; EC1.1.1.204; xanthine-NAD oxidoreductase) is a precursor of xanthine oxidase (XOD, o-form; EC 1.1.3.22; xanthine: oxygen oxidoreductase) that may be formed either by conversion of proteolytic cleavage of –SH (thiol)Cys535 located in the long peptide chain between FAD centre and molybdoprterin domains or by oxidation of sulfhydryl residues of protein molecule.[2] Corte and Stirpe[3] reported XDH as a native form of XOD and both are responsible to control the rate limiting step of nucleic acid oxidation. XOR is gaining interest due to its use in food processing industries and medical diagnostics to monitor xanthine (XN) and hypoxanthine (HX) using enzyme-based analytical methods such as biosensor, spectrophotometric and immunologic analyses. Quantification of XN and HX is useful to detect freshness of fish/meat derivatives in food processing industries.[4] XOR has potential to treat many diseases, e.g., hyperuricemia, gout, xanthinuria and renal failure. Hence, large scale production of XOR is important for low cost monitoring of XN in biological samples. Commercial enzyme production is achieved by overproducing biomass of selective strains that synthesise desired enzyme at optimal fermentation parameters. Separation and purification of the enzyme from an organism involve few crucial steps such as screening of microorganism, enrichment in media, optimisation of fermentation conditions, disruption of the cells, removal of cell debris and nucleic acids, precipitation of proteins, ultrafiltration and chromatographic purification of the desired enzyme.