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Dual substrate recognition of aminotransferases
Author(s) -
Hirotsu Ken,
Goto Masaru,
Okamoto Akihiro,
Miyahara Ikuko
Publication year - 2005
Publication title -
the chemical record
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.61
H-Index - 78
eISSN - 1528-0691
pISSN - 1527-8999
DOI - 10.1002/tcr.20042
Subject(s) - transamination , amino acid , side chain , glutamine , chemistry , stereochemistry , substrate (aquarium) , pyridoxal phosphate , aromatic amino acids , alanine , hydrogen bond , biochemistry , molecule , enzyme , organic chemistry , cofactor , biology , ecology , polymer
Pyridoxal 5′‐phosphate‐dependent aminotransferases reversibly catalyzes the transamination reaction in which the α‐amino group of amino acid 1 is transferred to the 2‐oxo acid of amino acid 2 (usually 2‐oxoglutarate) to produce the 2‐oxo acid of amino acid 1 and amino acid 2 (glutamate). An aminotransferase must thus be able to recognize and bind two kinds of amino acids (amino acids 1 and 2), the side chains of which are different in shape and properties, from among many other small molecules. The dual substrate recognition mechanism has been discovered based on three‐dimensional structures of aromatic amino acids, histidinol phosphate, glutamine : phenylpyruvate, acetylornithine, and branched‐chain amino acid aminotransferases. There are two representative strategies for dual substrate recognition. An aromatic amino acid aminotransferase prepares charged and neutral pockets for acidic and aromatic side chains, respectively, at the same place by a large‐scale rearrangement of the hydrogen‐bond network caused by the induced fit. In a branched‐chain aminotransferase, the same hydrophobic cavity implanted with hydrophilic sites accommodates both hydrophobic and acidic side chains without side‐chain rearrangements of the active‐site residues, which is reminiscent of the lock and key mechanism. Dual substrate recognition in other aminotransferases is attained by combining the two representative methods. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 160–172; 2005: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.20042