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The dimer contact area of sorghum NADP‐malate dehydrogenase: role of aspartate 101 in dimer stability and catalytic activity
Author(s) -
Schepens Isabelle,
Decottignies Paulette,
Ruelland Eric,
Johansson Kenth,
Miginiac-Maslow Myroslawa
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01405-8
Subject(s) - dimer , asparagine , protein subunit , enzyme , chemistry , malate dehydrogenase , biochemistry , thioredoxin , stereochemistry , gene , organic chemistry
During thioredoxin‐mediated activation of chloroplastic NADP‐malate dehydrogenase, a homodimeric enzyme, the interaction between subunits is known to be loosened but maintained. A modeling of the 3D structure of the protein identified Asp‐101 as being potentially involved in the association between subunits through an electrostatic interaction. Indeed, upon site‐directed substitution of Asp‐101 by an asparagine, the mutated enzyme behaved mainly as a monomer. The mutation strongly affected the catalytical efficiency of the enzyme. The now available 3D structure of the enzyme shows that Asp‐101 is protruding at the dimer interface, interacting with Arg‐268 of the neighbouring subunit.