کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1194223 1492288 2012 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Infrared multiple photon dissociation spectroscopy of protonated histidine and 4-phenyl imidazole
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
Infrared multiple photon dissociation spectroscopy of protonated histidine and 4-phenyl imidazole
چکیده انگلیسی

The gas-phase structures of protonated histidine (His) and the side-chain model, protonated 4-phenyl imidazole (PhIm), are examined by infrared multiple photon dissociation (IRMPD) action spectroscopy utilizing light generated by the free electron laser FELIX. To identify the structures present in the experimental studies, the measured IRMPD spectra are compared to spectra calculated at a B3LYP/6–311+G(d,p) level of theory. Relative energies of various conformers are provided by single point energy calculations carried out at the B3LYP, B3P86, and MP2(full) levels using the 6–311+G(2d,2p) basis set. On the basis of these experiments and calculations, the IRMPD action spectrum for H+(His) is characterized by a mixture of [Nπ,Nα] and [Nπ,CO] conformers, with the former dominating. These conformers have the protonated nitrogen atom of imidazole adjacent to the side-chain (Nπ) hydrogen bonding to the backbone amino nitrogen (Nα) and to the backbone carbonyl oxygen, respectively. Comparison of the present results to recent IRMPD studies of protonated histamine, the radical His+ cation, H+(HisArg), H22+(HisArg), and M+(His), where M+ = Li+, Na+, K+, Rb+, and Cs+, allows evaluation of the vibrational motions associated with the observed bands.

Figure optionsDownload high-quality image (117 K)Download as PowerPoint slideHighlights
► Protonated histidine (His) and 4-phenyl imidazole (PhIm) are examined by infrared multiple photon dissociation (IRMPD) action spectroscopy.
► Structures are determined by comparing the spectra with B3LYP/6–311+G(d,p) predictions.
► The dominant structure of H+(His) has the protonated nitrogen atom of imidazole hydrogen bonding to the backbone amino nitrogen.
► Results are compared to IRMPD studies of protonated histamine, radical His+, H+(HisArg), H22+(HisArg), and M+(His), where M+ = alkali cations.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Mass Spectrometry - Volumes 330–332, 15 December 2012, Pages 6–15
نویسندگان
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