Related Experiment Videos
[Accessibility of tryptophan residues in immunoglobulin M molecule as an indicator of its conformational variability]
Abstract:
The accessibility of tryptophan residues in immunoglobulin M to modification with the Koshland reagent (2-hydroxy-5-nitrobenzyl bromide) was used as an indicator of its conformational variability. Of 14 tryptophan residues (per HL-fragment) in the native IgM, only one (presumably Trp312 in the mu-chain) was the most accessible. Irreversible acid- or temperature-induced conformational changes of IgM increased almost 2-fold the number of accessible tryptophan residues. After partial enzymatic deglycosylation of IgM (especially by an intense splitting of mannose), all tryptophan residues became inaccessible. Modification of the most accessible tryptophan residue increased 2- to 3-fold the number of tyrosine residues accessible to nitration with tetranitromethane. Using the spin label method, it was demonstrated that modification of four tryptophan residues in IgM considerably decreased the mobility of the Cmu 3 domain together with an essential drop in. the solubility of the modified IgM.
Insights
Immunoglobulin M (IgM) conformation changes reveal accessible tryptophan residues. Deglycosylation makes all tryptophan residues inaccessible, impacting IgM structure and function.
Area of Science:
- Biochemistry
- Immunology
- Structural Biology
Context:
- Immunoglobulin M (IgM) is a crucial antibody in the immune system.
- Understanding IgM's conformational flexibility is key to its function.
- Tryptophan residue accessibility serves as a probe for protein conformation.
Purpose:
- To investigate the conformational variability of immunoglobulin M (IgM).
- To assess the impact of chemical modifications and deglycosylation on IgM structure.
- To correlate tryptophan accessibility with changes in IgM's biophysical properties.
Summary:
- The accessibility of tryptophan residues in immunoglobulin M (IgM) was studied using Koshland reagent.
- Native IgM has one accessible tryptophan residue (Trp312), while acid/heat treatment exposes more.
- Enzymatic deglycosylation renders all tryptophan residues inaccessible, significantly altering IgM structure and reducing solubility.
Impact:
- Reveals that deglycosylation drastically affects IgM conformation and reduces its solubility.
- Demonstrates a link between tryptophan modification, tyrosine accessibility, and Cmu 3 domain mobility.
- Provides insights into the structural dynamics of IgM and its functional implications.