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Role of invariant water molecules and water-mediated ionic interactions in D-xylose isomerase from Streptomyces rubiginosus |
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| Authors: | V Dhanasekaran Shankar Prasad Kanaujia K Sekar |
| Institution: | 1. Centre of Advanced Study in Crystallography and Biophysics , University of Madras , Guindy Campus, Chennai , 600 025 , India;2. Supercomputer Education and Research Centre , Indian Institute of Science , Bangalore , 560 012 , India |
| Abstract: | The enzyme, D-xylose isomerase (D-xylose keto-isomerase; EC 5.3.1.5) is a soluble enzyme that catalyzes the conversion of the aldo-sugar D-xylose to the keto-sugar D-xylulose. A total of 27 subunits of D-xylose isomerase from Streptomyces rubiginosus were analyzed in order to identify the invariant water molecules and their water-mediated ionic interactions. A total of 70 water molecules were found to be invariant. The structural and/or functional roles of these water molecules have been discussed. These invariant water molecules and their ionic interactions may be involved in maintaining the structural stability of the enzyme D-xylose isomerase. Fifty-eight of the 70 invariant water molecules (83%) have at least one interaction with the main chain polar atom. |
| Keywords: | invariant water molecules ion pairs protein stability water-mediated ionic interactions D-xylose isomerase Streptomyces rubiginosus |