ABSTRACT
Natural recombination combines pieces of preexisting proteins to create new tertiary structures and functions. We describe a computational protocol, called SEWING, which is inspired by this process and builds new proteins from connected or disconnected pieces of existing structures. Helical proteins designed with SEWING contain structural features absent from other de novo designed proteins and, in some cases, remain folded at more than 100°C. High-resolution structures of the designed proteins CA01 and DA05R1 were solved by x-ray crystallography (2.2 angstrom resolution) and nuclear magnetic resonance, respectively, and there was excellent agreement with the design models. This method provides a new strategy to rapidly create large numbers of diverse and designable protein scaffolds.
Subject(s)
Computer Simulation , Models, Chemical , Protein Engineering/methods , Proteins/chemistry , Proteins/genetics , Biological Evolution , Crystallography, X-Ray , Magnetic Resonance Spectroscopy , Protein Structure, SecondaryABSTRACT
Intrathoracic esophageal squamous cell carcinoma was diagnosed by endoscopy in an 11-year-old, castrated male Labrador retriever with signs of regurgitation and weight loss. Photodynamic therapy with photofrin was administered three times under endoscopic guidance over a two-month period. A partial response to photodynamic therapy was supported by a reduction in tumor size (noted on serial endoscopic examinations) and by a return to oral alimentation. The dog was euthanized due to recurrent regurgitation and aspiration pneumonia nine months after the onset of therapy. Necropsy revealed marked local invasiveness and regional lymph node metastasis of the esophageal squamous cell carcinoma in addition to pneumonia. The application of photodynamic therapy in the treatment of canine esophageal squamous cell carcinoma is discussed and compared with the human literature.
