Complex formation between spin-labeled polyuridylic acid and pyrimidine nucleosides

Area of Science:

• Biochemistry
• Molecular Biology
• Polymer Science

Background:

• Polyuridylic acid (poly (U)) is a synthetic polynucleotide.
• Nucleoside interactions with nucleic acids are fundamental to molecular biology.
• Understanding binding mechanisms provides insights into molecular recognition.

Purpose of the Study:

• To investigate complex formation between poly (U) and pyrimidine nucleosides (uridine, cytidine).
• To characterize the binding interactions, including cooperativity and contributing forces.
• To determine thermodynamic parameters of the complex formation process.

Main Methods:

• Spin labeling technique was employed to study binding.
• Binding isotherms were analyzed to obtain thermodynamic data.
• Complex formation with adenosine was also investigated for comparison.

Main Results:

• Poly (U) forms complexes with uridine and cytidine via a cooperative binding mechanism.
• Both hydrogen bonding and stacking interactions contribute to complex stability.
• Equilibrium constants for nucleation and chain growth were quantified at 21°C for uridine and cytidine.

Conclusions:

• The study elucidates the molecular interactions governing poly (U)-nucleoside complex formation.
• Spin labeling is an effective method for characterizing such binding events.
• Thermodynamic data provide quantitative insights into the stability and binding modes of these complexes.