Multiple charge isomers of human recombinant interleukin-1 beta

Area of Science:

• Biochemistry
• Immunology
• Molecular Biology

Background:

• Interleukin-1 beta (IL-1 beta) is a key inflammatory cytokine.
• Understanding IL-1 beta's properties is crucial for immunology and drug development.
• Recombinant DNA technology allows for the production of specific protein variants.

Purpose of the Study:

• To characterize the isoelectric properties of recombinant human interleukin-1 beta (rhuIL-1 beta).
• To investigate the potential charge heterogeneity of the rhuIL-1 beta molecule.
• To determine the molecular mass and identify charged variants of rhuIL-1 beta.

Main Methods:

• Radiolabelling of rhuIL-1 beta produced via DNA recombinant technology.
• Isoelectric focusing (IEF) on polyacrylamide gels of varying thickness and pH ranges.
• Chromatofocusing in a liquid column.
• Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) for molecular mass determination.

Main Results:

• rhuIL-1 beta resolved into multiple bands on IEF, indicating charge heterogeneity.
• Two broad bands were observed in the pH ranges of 6.2-5.8 and 5.5-5.2.
• Further resolution into multiple bands occurred with thinner gels and narrower pH ranges.
• Chromatofocusing isolated various charged components, all of which reacted to IL-1 beta antiserum.
• SDS-PAGE confirmed a consistent molecular mass of 18 kDa for all components.

Conclusions:

• Recombinant human interleukin-1 beta (rhuIL-1 beta) demonstrates significant charge heterogeneity.
• This heterogeneity is independent of the 18 kDa molecular mass.
• IEF and chromatofocusing are effective techniques for resolving charged protein variants.
• The findings contribute to a deeper understanding of IL-1 beta's molecular characteristics.