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Lysine epsilon-aminotransferases: kinetic constants, substrate specificities, and the variation in active site residues

Title
Lysine epsilon-aminotransferases: kinetic constants, substrate specificities, and the variation in active site residues
Authors
Seo, Joo-HyunKim, Eun-MiChae, AhramKim, Byung-Gee
Ewha Authors
서주현
SCOPUS Author ID
서주현scopusscopus
Issue Date
2016
Journal Title
ENZYME AND MICROBIAL TECHNOLOGY
ISSN
0141-0229JCR Link1879-0909JCR Link
Citation
vol. 84, pp. 11 - 16
Keywords
Lysine epsilon-aminotransferaseSubstrate specificityEnzyme characterizationKinetic constantsSequence analysisStructural analysis
Publisher
ELSEVIER SCIENCE INC
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
L-Lysine epsilon-aminotransferase (lysAT) is an important enzyme in tailoring the terminal amino group of L-lysine or L-ornithine and can be directed to the synthesis of various value-added chemicals such as adipic acid. Three lysATs, lysAT from Saccharopolyspora erythraea NRRL 2338 (lysAT_Sery), lysAT from Nocardia farcinica IFM 10152, and lysAT from Rhodococcus jostii RHA1, were cloned, and their kinetic values and substrate specificities were investigated. In the reaction using 5 mM L-lysine and 10 mM alpha-ketoglutarate, lysAT_Sery from S. erythraea NRRL 2338 showed 72% higher specific activity than lysAT from Nocardia farcinica IFM 10152 and 42% higher specific activity than lysAT from R. jostii RHA1. More interesting result was that lysAT Sery, exhibiting the highest activity among three lysATs, did not show any activity to L-ornithine. The alignment of 146 lysAT sequences from RefSeq database was searched by the EC number of lysAT to compare the active site residues among the lysAT sequences. The sequence alignment showed that only two residues, corresponding to A1a129 and Asn328 of lysAT from Mycobacterium tuberculosis H37Rv (lysAT_Mtub), showed variations among the active site residues. All the active site residues except those two residues were completely conserved throughout 145 lysAT sequences. lysAT from S. erythraea NRRL 2338 has A129T and N328S variations (residue numbers are those of the crystal structure of lysAT_Mtub). The structural analysis by the homology model indicate that Thr126 by A129T variation in lysAT_Sery is appeared to interact more tightly with the phosphate group of PLP than alanine (the distance between Thr126 and the phosphate group of PLP was 2.92 angstrom). In addition, Ser328 is located at the substrate recognition site of active site and, therefore, N328S variation may be connected to the substrate specificity of lysAT. (C) 2015 Published by Elsevier Inc.
DOI
10.1016/j.enzmictec.2015.12.001
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엘텍공과대학 > 식품공학전공 > Journal papers
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