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Protein & Peptide Letters

Editor-in-Chief

ISSN (Print): 0929-8665
ISSN (Online): 1875-5305

Effect of Metal Ions and EGTA on the Optical Properties of Concanavalin A at Alkaline pH

Author(s): Mohammad Tashfeen Ashraf and Rizwan Hasan Khan

Volume 12, Issue 2, 2005

Page: [203 - 206] Pages: 4

DOI: 10.2174/0929866053005827

Price: $65

Abstract

In our earlier communications, we reported the effect of salts and alcohols on a-chymotrypsinogen [1] and the existence of stable intermediates at low pH in bromelain [2] and glucose oxidase [3]. In the present study, the role of metal ions and EGTA on the conformation of concanavalin A at alkaline pH was studied by near- and far-UV circular dichroism, fluorescence emission spectroscopy and binding of a hydrophobic dye, 1-anilino-8-naphthalene sulfonate (ANS). Far-UV CD spectra showed the transition from an ordered secondary structure at pH 7 with a trough at 223 nm to a relatively unordered state at pH 12. Near-UV CD spectra showed the loss of signal at 290 nm, thereby indicating the disruption of native three dimensional structure. Maximum ANS binding occurred at pH 12 suggesting the presence of an intermediate or molten globule-like state at alkaline pH.

Keywords: concanavalin a, alkaline ph, metal ions, egta, molten globule


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