title: Bis-azobenzene crosslinkers for photocontrol of peptide structure.
abstract: Crosslinkers that undergo large changes in length upon photoisomerization can produce large conformational changes, and thereby functional changes, in biomolecules. We have designed and synthesized extended and rigid bis-azobenzene crosslinkers: 4,4'-bis(4-(2-chloroacetamido)phenyl)diazenylbiphenyl (BPDB) and the water-soluble sulfonated analogue 4,4'-bis(4-(2-chloroacetamido)phenyl)diazenylbiphenyl-2,2'-disulfonate (BPDBS). These photoswitches can produce end-to-end distance changes of a minimum of ≈5 Å and a maximum of ≈23 Å upon trans/cis isomerization. They have high absorption coefficients (45-60 000 M(-1)  cm(-1) ) and can produce up to ≈80 % cis isomers under favorable conditions. The photoswitching behavior of BPDBS-crosslinked peptides was found to be highly dependent on the crosslinker attachment site. Upon UV irradiation (365 nm), significant decreases in α-helix content were observed for peptides that were crosslinked with BPDBS through Cys residues at i,i+19, and i,i+21 positions. In contrast, large increases in α-helix content were exhibited by i,i+11 crosslinked peptides. BPDBS thus constitutes a particularly bright and effective photoswitch for biomolecule photocontrol.
authors.affiliation: Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON, M5S 3H6, Canada.
authors.forename: Subhas
authors.initials: S
authors.lastname: Samanta
authors.forename: G Andrew
authors.initials: GA
authors.lastname: Woolley
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D007536:Isomerism; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D055668:Photochemical Processes; D017433:Protein Structure, Secondary
chemical_list: D001391:Azo Compounds; D003432:Cross-Linking Reagents; D010455:Peptides; C009850:azobenzene