Heterologous expression of human transketolase

Schenk, Gerhard and Duggleby, Ronald and Nixon, Peter (1998) Heterologous expression of human transketolase. The International Journal of Biochemistry & Cell Biology, 30. pp. 369-378. ISSN 1357-2725

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Transketolase belongs to the family of thiamin diphosphate dependent enzymes. The aim of this study was to establish a bacterial expression system for human transketolase in order to investigate the functional characteristics of mammalian transketolases. The level of recombinant human enzyme expressed in Escherichia coli was modest. Puri®cation of recombinant transketolase and separation from the E. coli enzyme has been greatly simpli®ed by means of a non-cleavable hexa-histidine tag. The highest speci®c activity was 13.5 U/mg and the Km values were 0.2720.02 and 0.5120.05 mM for the substrates D-xylulose 5-phosphate and D-ribose 5-phosphate, respectively. Binding of cofactors to the apoenzyme showed the expected hysteresis. Without preincubation, the Km values for thiamin diphosphate and for Mg2+ were, respectively, 4.120.8 and 2.520.4 mM, but after 1 h of preincubation these values were 85216 nM and 0.7420.23 mM. The kinetic constants are similar to those of the native enzyme puri®ed from human erythrocytes. Despite the modest expression level the reported system is well suited to a variety of functional studies.

Item Type: Article
Keywords: Thiamin diphosphate; Heterologous expression; Protein purifcation; Kinetic parameters; Recombinant human transketolase;
Academic Unit: Faculty of Science and Engineering > Chemistry
Item ID: 3687
Depositing User: Gary Schenk
Date Deposited: 28 May 2012 14:43
Journal or Publication Title: The International Journal of Biochemistry & Cell Biology
Publisher: Elsevier Science Ltd
Refereed: Yes

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