title: Variation in proton affinity of the guanidino group between free and blocked arginine.
abstract: In this paper, the analog of arginine residues in peptides was synthesized and characterized by ESI-MS/MS (electrospray ionization with tandem mass spectrometry), (31)P NMR, (1)H NMR, IR and high-resolution mass spectrometry. When the Todd reaction activity of the guanidino group in free arginine and the arginine peptide analog were compared, it was found that the proton affinity of the guanidino group was decreased when both the N- and the C-terminal were blocked. As a result, the guanidino group of arginine residues in peptides could be phosphorylated under the Todd reaction condition, but not the free arginine. This result was further proved by the theoretical calculation of their proton affinity.
authors.affiliation: The Key Laboratory for Chemical Biology of Fujian Province, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: L
authors.initials: L
authors.lastname: Jin
authors.forename: J-B
authors.initials: JB
authors.lastname: Hou
authors.forename: P-X
authors.initials: PX
authors.lastname: Xu
authors.forename: Y-F
authors.initials: YF
authors.lastname: Zhao
mesh_terms: D001120:Arginine / Q000737:chemistry* / Q000378:metabolism; D019791:Guanidine / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D011522:Protons; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D010446:Peptide Fragments; D011522:Protons; D001120:Arginine; D019791:Guanidine