Structure of Starch Binding Domains of Halophilic Alpha-Amylase at Low pH

Author(s): Rui Yamaguchi, Matsujiro Ishibashi, Hiroko Tokunaga, Tsutomu Arakawa, Masao Tokunaga.

Journal Name: Protein & Peptide Letters

Volume 20 , Issue 7 , 2013

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The solubility and structural properties of halophilic proteins are ascribed to their abundant acidic residues, resulting in large net negative charges at neutral pH. This study examined the effects of low pH, i.e., reduction of net negative charges on the structural properties of starch binding domain (SBD) of halophilic Kocuria varians α-amylase. Titration to pH 2.1 caused loss of 233 nm peak characteristic of aromatic interactions present in the native SBD at neutral pH and resulted in the spectrum with a 216 nm valley characteristic of β-sheet. The low pH β-sheet structure was stable against heat treatment. The addition of NaCl and trifluoroethanol resulted in decrease and increase of the 216 nm signal, without altering the spectral shape. These structural properties were significantly different from those of the native protein.

Keywords: Halophilic, starch binding domain, low pH, circular dichroism, melting.

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Article Details

Year: 2013
Page: [755 - 760]
Pages: 6
DOI: 10.2174/0929866511320070004
Price: $58

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