NISCAIR Online Periodicals Repository

Research Journals >
Indian Journal of Biochemistry and Biophysics (IJBB) >
IJBB Vol.45 [2008] >
IJBB Vol.45(6) [December 2008] >

Title: Effect of Na+ ions on pH-dependent conformational changes in brush border sucrase-isomaltase in mice intestine
Authors: Gupta, Shiffalli
Mahmood, Safrun
Khan, Rizwan Hasan
Mahmood, Akhtar
Keywords: Brush border sucrase
Mice intestine
Alkali metal ions
pH-dependent effects
UV-CD spectral analysis
Fluorescence spectral studies
Issue Date: Dec-2008
Publisher: CSIR
Abstract: Intestinal brush border sucrase-isomaltase (sucrose D-glucosidase E.C., E.C. exhibits pH-dependent stimulatory or inhibitory effects in response to Na⁺ ions. However, whether the enzyme undergoes conformational modulations as a function of pH and in the presence of alkali metal ions is not known. In this paper, we investigated the structural and functional relationship of purified murine sucrase in response to pH and Na⁺ ions using UV-CD fluorescence and spectroscopic studies. Kinetic studies revealed that at pH 5.0, the enzyme activation by Na⁺ ions was V-type, which changed to K-type at pH 7.2, whereas at alkaline pH (8.5), Na⁺ ions inhibited the enzyme activity and inhibition was uncompetitive in nature, affecting both the Km and Vmax components. Far UV-CD spectra of protein at pH 7.2 in the absence and presence of Na⁺ were almost overlapping, suggesting that secondary structure of protein was not affected upon addition of the salt. However, near UV-CD spectra indicated marked alterations in the tertiary structure of protein in presence of 50 mM Na⁺ ions. Increase in pH from 7.2 to 8.5 resulted in a marked rise in fluorescence intensity and red shift in λmax due to tryptophan residues in the enzyme molecule. These findings suggested that alterations in enzyme activity as a function of pH and Na⁺ ions was associated with ionization of key amino acid residues together with structural modifications in the enzyme conformation around neutral or alkaline pH.
Page(s): 399-403
ISSN: 0301-1208
Source:IJBB Vol.45(6) [December 2008]

Files in This Item:

File Description SizeFormat
IJBB 45(6) 399-403.pdf228.02 kBAdobe PDFView/Open
 Current Page Visits: 783 
Recommend this item


Online Submission of Articles |  NISCAIR Website |  National Knowledge Resources Consortium |  Contact us |  Feedback

Disclaimer: NISCAIR assumes no responsibility for the statements and opinions advanced by contributors. The editorial staff in its work of examining papers received for publication is helped, in an honorary capacity, by many distinguished engineers and scientists.

CC License Except where otherwise noted, the Articles on this site are licensed under Creative Commons License: CC Attribution-Noncommercial-No Derivative Works 2.5 India

Copyright © 2015 The Council of Scientific and Industrial Research, New Delhi. All rights reserved.

Powered by DSpace Copyright © 2002-2007 MIT and Hewlett-Packard | Compliant to OAI-PMH V 2.0

Home Page Total Visits: 171343 since 01-Sep-2015  Last updated on 30-Jun-2016Webmaster: