Peptide Backbone (IMAGE) The Geisel School of Medicine at Dartmouth Caption The P99 beta lactamase peptide backbone is shown in complex with a beta lactam substrate (PDB file 4KEN), which is rendered as a stick figure with carbon in cyan, nitrogen in dark blue, oxygen in red, and sulfur in yellow. Shown as thick green tubes are overlapping immunogenic epitopes targeted for deletion by introduction of structurally optimized deimmunizing mutations, whose positions are shown as blue spheres. Structure based deimmunization enabled targeting of high risk immunogenic subsequences that were located both distal and proximal to the enzyme's active site. Credit NCCC Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.