[Thymidine kinase from sea urchin oocytes]

Area of Science:

• Biochemistry
• Molecular Biology
• Marine Biology

Background:

• Thymidine kinase is a key enzyme in DNA synthesis.
• Understanding its properties is crucial for various biological processes.
• Sea urchin oocytes are a rich source of biological molecules.

Purpose of the Study:

• To isolate and purify thymidine kinase from sea urchin (Strongylocentrotus intermedius) oocytes.
• To characterize the biochemical properties of the purified enzyme.

Main Methods:

• Enzyme isolation and purification (1600-fold).
• Determination of molecular mass and isoelectric point (pI).
• Enzyme activity assays under varying conditions and substrates.

Main Results:

• Purified thymidine kinase has a molecular mass of 66 kDa and pI of 5.2.
• Optimal activity occurs at pH 9.0-9.5, requiring Mg2+ and ATP.
• The enzyme phosphorylates thymidine, deoxycytidine, and other pyrimidine nucleosides, with maximal rates for thymidine and ATP or dATP.
• Product inhibition by thymidine monophosphate (TMP) was not observed.

Conclusions:

• A novel thymidine kinase from sea urchin oocytes has been purified and characterized.
• The enzyme exhibits broad substrate specificity and is potentially involved in nucleotide metabolism.
• Its properties provide insights into DNA precursor synthesis in marine invertebrates.