Affinity of human leukocyte interferon for polyribonucleotides

Area of Science:

• Immunology
• Biochemistry
• Molecular Biology

Background:

• Human leukocyte interferon (HL-IF) is a crucial component of the innate immune system.
• Understanding interferon interactions with nucleic acids is key to elucidating immune responses.
• Polyribonucleotides serve as models for studying protein-nucleic acid interactions.

Purpose of the Study:

• To investigate the binding characteristics of human leukocyte interferon (HL-IF) to various polyribonucleotides.
• To determine the nature of the interaction (electrostatic vs. hydrophobic) between HL-IF and polyribonucleotides.
• To assess the influence of pH and ionic strength on HL-IF binding to polyribonucleotides.

Main Methods:

• Affinity chromatography using immobilized polyribonucleotides (AGPOLY(A)TM, AGPOLY(U)TM, AGPOLY(I)TM) to bind HL-IF.
• Elution studies using varying concentrations of sodium chloride to quantify binding affinity.
• Binding assays in the presence of ethylene glycol to differentiate between electrostatic and hydrophobic interactions.
• pH-dependent binding experiments to assess the effect of acidity on HL-IF-polyribonucleotide interactions.

Main Results:

• Human leukocyte interferon (HL-IF) demonstrated binding to AGPOLY(A)TM, AGPOLY(U)TM, and AGPOLY(I)TM.
• The binding interaction was confirmed to be electrostatic, as it was not inhibited by 50% ethylene glycol.
• Increasing sodium chloride concentrations were required to displace bound HL-IF, indicating ionic interactions.
• HL-IF binding to AGPOLY(I)TM was stronger at lower pH, necessitating higher ionic strength for displacement.

Conclusions:

• Human leukocyte interferon (HL-IF) interacts electrostatically with specific polyribonucleotides.
• The binding affinity is influenced by pH, with enhanced binding observed under acidic conditions.
• These findings contribute to understanding the molecular mechanisms of interferon-nucleic acid interactions in immune regulation.