title: Kinetics of a collagen-like polypeptide fragmentation after mid-IR free-electron laser ablation.
abstract: Tissue ablation with mid-infrared irradiation tuned to collagen vibrational modes results in minimal collateral damage. The hypothesis for this effect includes selective scission of protein molecules and excitation of surrounding water molecules, with the scission process currently favored. In this article, we describe the postablation infrared spectral decay kinetics in a model collagen-like peptide (Pro-Pro-Gly)(10). We find that the decay is exponential with different decay times for other, simpler dipeptides. Furthermore, we find that collagen-like polypeptides, such as (Pro-Pro-Gly)(10), show multiple decay times, indicating multiple scission locations and cross-linking to form longer chain molecules. In combination with data from high-resolution mass spectrometry, we interpret these products to result from the generation of reactive intermediates, such as free radicals, cyanate ions, and isocyanic acid, which can form cross-links and protein adducts. Our results lead to a more complete explanation of the reduced collateral damage resulting from infrared laser irradiation through a mechanism involving cross-linking in which collagen-like molecules form a network of cross-linked fibers.
authors.affiliation: Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235, USA.
authors.forename: Andrey
authors.initials: A
authors.lastname: Zavalin
authors.forename: David L
authors.initials: DL
authors.lastname: Hachey
authors.forename: Munirathinam
authors.initials: M
authors.lastname: Sundaramoorthy
authors.forename: Surajit
authors.initials: S
authors.lastname: Banerjee
authors.forename: Steven
authors.initials: S
authors.lastname: Morgan
authors.forename: Leonard
authors.initials: L
authors.lastname: Feldman
authors.forename: Norman
authors.initials: N
authors.lastname: Tolk
authors.forename: David W
authors.initials: DW
authors.lastname: Piston
mesh_terms: D003094:Collagen / Q000737:chemistry* / Q000528:radiation effects* / Q000648:ultrastructure; D003198:Computer Simulation; D004583:Electrons; D007259:Infrared Rays; D007834:Lasers; D008956:Models, Chemical; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry* / Q000528:radiation effects*; D011829:Radiation Dosage
chemical_list: D010455:Peptides; D003094:Collagen