Proteins have complex secondary, tertiary, and quaternary structrues, and their amino acid sequences determine how they interact with other molecules. The one amino acid mutation creates a new chemistry shape on the protein surface which, under low-oxygen conditions, causes the proteins to link together non-covalently and make filaments.
Work Step by Step
Review the material from Ch. 5 on protein shape. Use your imagination to see how a changed amino acid on the outside of the protein changes its ability to interact with other proteins, including other copies of itself, making a new quaternary structure (the filament).