Abstract
The stepwise synthesis of thymidine triphosphate (TTP) requires a kinase for phosphorylation in the last step. Because pyruvate kinase (PK) using phosphoenolpyruvate (PEP) as substrate can regenerate adenosine triphosphate and phosphorylate thymidine diphosphate as well, we chose this enzyme for the synthesis of TTP via an enzymatic cascade reaction. The metalloenzyme PK shows pronounced promiscuity and therefore fits well to the conditions of this reaction. PK commonly used today is isolated from rabbit muscle. We cloned and expressed the respective open reading frame in Escherichia coli, purified, and characterized the His-tagged recombinant enzyme. The enzyme has an activity optimum at 37°C and in the pH range from 7.4 to 7.8. Km constants conformed well with the isolated native enzyme for adenosine diphosphate (ADP) to 0.37±0.02 mm and for PEP to 0.07±0.01 mm. The recombinant enzyme shows the following range in its substrate specificity: ADP>dADP>dGDP>dCDP>thymidine diphosphate (TDP). It allows the phosphorylation of TDP to TTP in high yield (up to 95%). The metal ions Mg2+ and K+ are necessary for full enzymatic activity. The addition of transition metal ions such as Mn2+, Cu2+, Co2+, and Ni2+ reduces activity. Storage of the enzyme at -20°C retains full activity.
©2013 by Walter de Gruyter Berlin Boston
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Articles in the same Issue
- Masthead
- Masthead
- Guest Editorial
- Highlight: European BioEnergetics Conference 2012 in Freiburg
- Highlight: European Bioenergetics Conference 2012 in Freiburg
- Structure of caa3 cytochrome c oxidase – a nature-made enzyme-substrate complex
- Recent advances in the electrochemistry and spectroelectrochemistry of membrane proteins
- pKa values and redox potentials of proteins. What do they mean?
- Cyclophilin D as a potential target for antioxidants in neurodegeneration: the X-ALD case
- A critical appraisal of the role of respiratory supercomplexes in mitochondria
- Mechanistic aspects of sodium-binding sites in LeuT-like fold symporters
- Hydroxynonenal-stimulated activity of the uncoupling protein in Acanthamoeba castellanii mitochondria under phosphorylating conditions
- The antiporter-like subunit constituent of the universal adaptor of complex I, group 4 membrane-bound [NiFe]-hydrogenases and related complexes
- Alternate pathways for NADH oxidation in Thermus thermophilus using type 2 NADH dehydrogenases
- A new trend in the complex I research field
- Research Articles/Short Communications
- Protein Structure and Function
- Expression in non-melanogenic systems and purification of soluble variants of human tyrosinase
- Chemical and enzymatic characterization of recombinant rabbit muscle pyruvate kinase