In grad school I got interested in knots while doing structural biology and asked my advisor (extremely well known chemist) if it would be possible to make proteins that fold into knots and he pointed out (correctly) that entropy makes it very unlikely this would happen, as the process of folding into a knot typically decreases the degrees of freedom a protein can adopt. It was a reasonable point and I ignored the problem for some time.
It turned out later that a small number of proteins are found in a knotted conformation experimentally, https://en.wikipedia.org/wiki/Knotted_protein and alphafold even helped design a knotted protein. I can imagine there are also enzymatic modifications you can make to proteins that would generate knots without paying the entropic cost of threading the needle, so to speak.
It turned out later that a small number of proteins are found in a knotted conformation experimentally, https://en.wikipedia.org/wiki/Knotted_protein and alphafold even helped design a knotted protein. I can imagine there are also enzymatic modifications you can make to proteins that would generate knots without paying the entropic cost of threading the needle, so to speak.