University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal

Logo BOKU Resarch Portal

Selected Publication:

Jakopitsch, C; Auer, M; Regelsberger, G; Jantschko, W; Furtmüller, PG; Rüker, F; Obinger, C.
(2003): The catalytic role of the distal site asparagine-histidine couple in catalase-peroxidases.
Eur J Biochem. 2003; 270(5):1006-1013 FullText FullText_BOKU

Catalase-peroxidases (KatGs) are unique in exhibiting an overwhelming catalase activity and a peroxidase activity of broad specificity. Similar to other peroxidases the distal histidine in KatGs forms a hydrogen bond with an adjacent conserved asparagine. To investigate the catalytic role(s) of this potential hydrogen bond in the bifunctional activity of KatGs, Asn153 in Synechocystis KatG was replaced with either Ala (Asn153-->Ala) or Asp (Asn153-->Asp). Both variants exhibit an overall peroxidase activity similar with wild-type KatG. Cyanide binding is monophasic, however, the second-order binding rates are reduced to 5.4% (Asn153-->Ala) and 9.5% (Asn153-->Asp) of the value of native KatG [(4.8 +/- 0.4) x 10(5) m(-1) .s(-1) at pH 7 and 15 degreesC]. The turnover number of catalase activity of Asn153-->Ala is 6% and that of Asn153-->Asp is 16.5% of wild-type activity. Stopped-flow analysis of the reaction of the ferric forms with H-2 O-2 suggest that exchange of Asn did not shift significantly the ratio of rates of H-2 O-2 -mediated compound I formation and reduction. Both rates seem to be reduced most probably because (a) the lower basicity of His123 hampers its function as acid-base catalyst and (b) Asn153 is part of an extended KatG-typical H-bond network, the integrity of which seems to be essential to provide optimal conditions for binding and oxidation of the second H-2 O-2 molecule necessary in the catalase reaction.
Authors BOKU Wien:
Auer Markus
Furtmüller Paul Georg
Jakopitsch Christa
Obinger Christian
Rüker Florian
Find related publications in this database (using NML MeSH Indexing)
Amino Acid Sequence -
Asparagine - chemistry
Base Sequence - chemistry
Catalase - chemistry
Catalysis - chemistry
Cyanides - metabolism
DNA Primers - metabolism
Histidine - chemistry
Kinetics - chemistry
Models, Molecular - chemistry
Molecular Sequence Data - chemistry
Peroxidase - chemistry
Sequence Homology, Amino Acid - chemistry
Spectrophotometry, Ultraviolet - chemistry

Find related publications in this database (Keywords)
Synechocystis PCC 6803
catalase activity
peroxidase activity
compound I

© BOKU Wien Imprint