Chemically Modified Human Immunoglobulin G: Hydrophobicity and Surface Activity at Air/Solution Interface

Area of Science:

• Biochemistry
• Surface Chemistry
• Protein Modification

Background:

• Human immunoglobulin G (IgG) is a key protein with diverse biological functions.
• Understanding protein-surface interactions is crucial for various applications, including drug delivery and biomaterials.

Purpose of the Study:

• To investigate the covalent modification of human IgG using fatty acid esters of N-hydroxysuccinimide.
• To evaluate the impact of alkyl chain length (C8 and C16) on IgG surface hydrophobicity and interfacial properties.

Main Methods:

• Covalent modification of human IgG with N-hydroxysuccinimide fatty acid esters (C8 and C16).
• Surface hydrophobicity measurements using the fluorescent probe 8-anilino-1-naphthalenesulfonate.
• Analysis of surface tension reduction and molecular cross-sectional areas (ΔA) at the air/solution interface.

Main Results:

• Modified IgGs exhibited increased surface hydrophobicity correlated with the number and length of attached alkyl chains.
• The modified IgGs demonstrated enhanced ability to decrease surface tension compared to native IgG.
• Attachment of C8 groups increased molecular cross-sectional area (ΔA) by 40-50%; further increase observed with C16 chains.

Conclusions:

• Covalent attachment of fatty acid esters significantly alters IgG hydrophobicity and interfacial behavior.
• Alkyl chain length plays a critical role in modulating the dimensions of protein segments at interfaces.
• These findings provide insights into tailoring protein properties for specific surface interactions.