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Ligand Induced Folding of the First Identified CBM69 Starch Binding Domain AmyP-SBD

[ Vol. 25 , Issue. 4 ]

Author(s):

Wei Zhang, Jigang Yu, Xuecheng Zhang*, Hui Peng*, Xinxin Li, Jiahai Zhang, Hongbin Sun and Xiaoming Tu   Pages 362 - 367 ( 6 )

Abstract:


AmyP is an α-amylase which shows preferential degradation to soluble starch. In this substrate preference its Starch Binding Domain (SBD), which was recently assigned to a new Carbohydrate Binding Module (CBM) family 69, plays an important role. In the present study, the SBD of AmyP (AmyP-SBD) was recombinantly expressed, purified, and structurally characterized. Using Circular Dichroism (CD), intrinsic fluorescence, and nuclear magnetic resonance (NMR) spectroscopy, the structures of AmyP-SBD in the absence and presence of substrate analogue β-cyclodextrin were measured. The results intriguingly showed that free form AmyP-SBD is partially unfolded, like a compact molten globule, and could be induced by the ligand to fold into a relatively rigid state. Further structure determination for folded AmyP-SBD revealed a topology distinctive from those of SBDs from other CBM families. Our data indicate AmyP-SBD is a structurally novel SBD, and this may be helpful for understanding the properties of AmyP-SBD and CBM69 and elucidation of functioning mechanism of AmyP.

Keywords:

Starch binding domain, molten globule, ligand induced folding, carbohydrate binding module family 69, AmyP, nuclear magnetic resonance.

Affiliation:

School of Life Sciences, Anhui University, Hefei, Anhui 230601, School of Life Sciences, Anhui University, Hefei, Anhui 230601, School of Life Sciences, Anhui University, Hefei, Anhui 230601, School of Life Sciences, Anhui University, Hefei, Anhui 230601, School of Life Sciences, Anhui University, Hefei, Anhui 230601, Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Academy of Sciences of China, Hefei 230031, Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026

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