Identification of a firefly luciferase active site peptide using a benzophenone-based photooxidation reagent.
Figure 1: Looking down through the pore of Alpha-hemolysin. Alpha-hemolysin, pdb designation 7ahl, is a heptameric transmembrane pore. Being a transmembrane protein it is fairly large, approximately 100 Å in size. The main feature of the protein is the beta-barrelFigure 1. This protein is currently being manipulated in DNA nanopore research. The beta-barrel has an opening of about 26 Å. The significant residues that DNA nanopore technology exploits are the lysine residues just above the beta-barrel, shown in Figure 2. The lysine residues shrink the opening of the beta-barrel to 12.6 Å which allows only a single strand of DNA to move through the pore. The portion of the protein above the beta-barrel is wide enough to accommodate a double stranded DNA molecule. Figure 3 shows a cutaway of the protein. Here we can see that the upper portion of the protein is much larger than the beta-barrel below it. This difference in size allows researchers the ability to harness coupled DNA-Enzyme complexes such as the Klenow fragment, to study the dynamics of the single strand of DNA as bases get added to it and therefore pulls the single strand of DNA up through the pore.