Photolytic control and infrared probing of amide I mode in the dipeptide backbone-caged with the 4,5-dimethoxy-2-nitrobenzyl group.
Alanine dipeptide analog 1 backbone-caged with a photolabile linker, 4,5-dimethoxy-2-nitrobenzyl (DmNb), was synthesized. UV-pulse-induced photochemical reaction of 1 was monitored by Fourier transform IR absorption spectroscopy under a steady-state condition or in a fast-scan mode. Upon photolysis of 1, the amide I band is changed from a doublet to a singlet with concomitant line shape changes of several IR bands. The change of the amide I band is directly associated with the photocleavage of the covalent N-C bond connecting the backbone amide of 2 to DmNb. Therefore, IR spectroscopy is useful for directly probing the photocleavage of backbone-caged peptide 1 and the concurrent release of native peptide 2. In contrast, UV-vis spectroscopy probing the irradiation-induced structural change of the 2-nitrobenzyl moiety itself may not provide a clue directly relevant to the photocleavage of such N-C bond. Time-resolved IR spectra recorded in a fast-scan mode after pulsed UV irradiation of 1 reveal that such photocleavage occurs at least faster than a few seconds of our instrumental time resolution.
Rhee
Hanju
H
Department of Chemistry and Center for Multidimensional Spectroscopy, Korea University, Seoul 136-701, Korea.
Lee
Jang-Soo
JS
Lee
Jihae
J
Joo
Cheonik
C
Han
Hogyu
H
Cho
Minhaeng
M
D003432:Cross-Linking Reagents; D004151:Dipeptides / Q000737:chemistry* / Q000528:radiation effects*; D009578:Nitrobenzenes; D010782:Photolysis; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013995:Time; D014466:Ultraviolet Rays
D003432:Cross-Linking Reagents; D004151:Dipeptides; D009578:Nitrobenzenes