The antibody–antigen interaction at an aqueous–solid interface: A study by means of polarized infrared ATR spectroscopy
✍ Scribed by N. Ockman
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1978
- Tongue
- English
- Weight
- 694 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
The determination of structural changes in antibodies due to their specific interaction with antigenic proteins is an important problem in understanding immunological responses. The method of polarized ATR infrared spectroscopy applied to protein films adsorbed on an appropriate solid surface can give information about the conformation of the polypeptide chains, as well as their orientation with respect to the surface. The adsorption of anti‐rabbit serum albumin onto monomolecular films of rabbit serum albumin, bovine serum albumin, and ovalbumin, and of anti‐ovalbumin onto films of rabbit serum albumin and ovalbumin at a Ge‐aqueous interface have been studied by this technique. The intensity of the amide I absorption indicates that the strengths of binding of these three albumin proteins with anti‐rabbit serum albumin is, under appropriate conditions, in the order rabbit > bovine ≫ ovalbumin; with anti‐ovalbumin, it is ovalbumin ≫ rabbit. Since the frequencies of the amide I band appear near 1655 cm^−1^ for all the proteins and protein complexes studied, the major contributions to their conformation comes from α‐helix and random‐coil structures. The average orientation of the transition moments of the amide I and A bands has been shown to be about 75° with respect to the surface normal. This indicates that the polypeptides chains are on the average approximately parallel to the surface for all the systems studied. Consequently, the effect of the specific antibody‐antigen interaction on the conformation and orientation of the former seems negligible in these films.