Saccharomyces cerevisiae nucleoside-diphosphate kinase: purification, characterization, and substrate specificity

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Nucleoside-diphosphate kinase (NDP kinase) is crucial for nucleic acid biosynthesis, catalyzing the phosphorylation of nucleoside diphosphates to triphosphates.
• Understanding the specific properties of NDP kinase from different organisms, like yeast, is essential for elucidating its role in cellular metabolism.

Purpose of the Study:

• To purify and characterize the nucleoside-diphosphate kinase enzyme from yeast.
• To determine the enzyme's molecular weight, subunit composition, substrate specificity, and kinetic properties.

Main Methods:

• Protein purification using standard biochemical techniques.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for molecular weight determination.
• Fast protein liquid chromatography (FPLC) Superose 12 gel filtration for native molecular weight estimation.
• Substrate specificity and kinetic studies using various nucleoside diphosphates and triphosphates.

Main Results:

• Purified yeast nucleoside-diphosphate kinase appeared homogeneous with a subunit molecular weight of 17,000-18,000 Da.
• Native molecular weight estimation indicated a tetrameric structure (68,000-70,000 Da).
• The enzyme displayed broad substrate specificity, with a preference for dTDP as a phosphate acceptor and UTP as a donor, suggesting involvement in both DNA and RNA metabolism.

Conclusions:

• Yeast nucleoside-diphosphate kinase is a tetrameric enzyme with broad substrate specificity.
• The enzyme's kinetic properties and substrate preferences support its role in the biosynthesis pathways for both DNA and RNA.