In “Why Proteins Aren’t Easily Recombined” (Biologic Institute, May 7, 2012), Ann Gauger explains,
There seems to be an idea floating about among some biologists that it is easy to recombine protein domains or swap bits of protein structure to generate new function. I suppose it comes from looking at simplified drawings of protein structure, and forgetting about the detailed atomic interactions required.
For non-biologists, let me explain why proteins aren’t easily recombined. A protein fold is typically composed of smaller structural elements called alpha helices or beta sheets, with unstructured loops of protein connecting them. These elements adopt a stereotyped pattern of folding because of hydrogen bonding patterns between amino acids. The illustration below from Axe (2010) shows these hydrogen bonding patterns as red dashed lines between the linked amino acids. For clarity, the side chains of each amino acid are faded out, while the backbone trace is in full color.
Note: Biologic Institute is not to be confused with BioLogos, which has been in the news around here lately.
Biologic Institute does science research from an ID perspective. BioLogos is a group of Christians in science which is the subject of current controversies here about their theological opinions.