Thermally induced disulfide bond exchanges in human IgE

Area of Science:

• Immunology
• Biochemistry
• Protein Chemistry

Background:

• Human immunoglobulin E (IgE) is crucial for allergic responses.
• Understanding IgE's structural stability under thermal stress is important for its handling and therapeutic applications.
• Previous studies have not fully elucidated the thermal denaturation pathways of IgE.

Purpose of the Study:

• To investigate the thermally induced structural changes in human IgE.
• To characterize the fragments resulting from heat treatment of IgE.
• To elucidate the role of disulfide bonds in IgE thermal denaturation.

Main Methods:

• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was employed.
• Human IgE (1 mg/ml) was heated at 56°C for several hours.
• Experiments were conducted both in the absence and presence of sodium dodecyl sulfate (0.1%).
• Dithiothreitol was used for reduction of disulfide bonds.

Main Results:

• In the absence of SDS, heating IgE led to aggregated forms reducible to heavy and light chains.
• In the presence of SDS, heating IgE resulted in five low molecular weight components (LHHL, HL, H, LL, L).
• Similar, but less pronounced, changes were observed in mouse monoclonal IgG1.
• The observed fragmentation pattern suggests a role for disulfide bond exchange.

Conclusions:

• Thermal denaturation of human IgE is significantly influenced by the presence of sodium dodecyl sulfate.
• The fragmentation of IgE upon heating in SDS is mediated by the exchange of intra- and inter-disulfide bonds.
• These findings provide insights into the structural dynamics of IgE under thermal stress.