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B-factor Analysis and Conformational Rearrangement of Aldose Reductase

[ Vol. 11 , Issue. 3 ]

Author(s):

Ganesaratnam K. Balendiran, J. Rajendran Pandian, Evin Drake, Anubhav Vinayak, Malkhey Verma and Duilio Cascio   Pages 151 - 160 ( 10 )

Abstract:


The NADPH-dependent reduction of glucose reaction that is catalyzed by Aldose Reductase (AR) follows a sequential ordered kinetic mechanism in which the co-factor NADPH binds to the enzyme prior to the aldehyde substrate. The kinetic/structural experiments have found a conformational change involving a hinge-like movement of a surface loop (residues 213-224) which is anticipated to take place upon the binding of the diphosphate moiety of NADPH. The reorientation of this loop, expected to permit the release of NADP+, represents the rate-limiting step of the catalytic mechanism. This study reveals: 1) The Translation/Libration/Screw (TLS) analysis of absolute B-factors of apo AR crystal structures indicates that the 212-224 loop might move as a rigid group. 2) Residues that make the flexible loop slide in the AR binary and ternary complexes. 3) The normalized B-factors separate this segment into three differnt clusters with fewer residues.

Keywords:

Aldo-keto reductase, B-factor, clustering, crystal structure, statistical analysis, structural dynamics, TLS.

Affiliation:

Department of Chemistry, WBSH 6017, Youngstown State University, One University Plaza, Youngstown, OH 44555, USA.

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