کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1192228 1492294 2012 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Competition between diketopiperazine and oxazolone formation in water loss products from protonated ArgGly and GlyArg
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
Competition between diketopiperazine and oxazolone formation in water loss products from protonated ArgGly and GlyArg
چکیده انگلیسی

The mechanism of peptide “b” fragment formation in collision-induced dissociation (CID) is generally understood as a nucleophilic attack from a carbonyl oxygen onto the electron deficient carbon of the dissociating amide bond forming a five-membered oxazolone ring structure. Nonetheless, other nucleophiles, such as the N-terminus and side-chain moieties (e.g., imidazole, guanidine), can in principle engage in a nucleophilic attack to induce amide backbone cleavage. Here, we apply a combination of infrared multiple photon dissociation (IRMPD) spectroscopy and computational chemistry to characterize the water loss, [M+H-H2O]+, product ions from protonated ArgGly and GlyArg. IRMPD spectra for [M+H-H2O]+ from ArgGly and GlyArg differ in the presence and absence of a characteristic band at 1885 cm−1, which is indicative of an oxazolone structure for ArgGly. The remaining parts of the vibrational spectra are consistent with the vibrational signatures of diketopiperazine structures. Conversely, there is no match between the experimental spectra and any of the putative structures arising from guanidine side-chain attack. These results show that the presence of a basic residue, such as arginine, facilitates the formation of diketopiperazine structures, and that residue order matters in the competition between diketopiperazine and oxazolone pathways.

Figure optionsDownload high-quality image (112 K)Download as PowerPoint slideHighlights
► The water loss products from protonated ArgGly and GlyArg are investigated by infrared multiple photon dissociation spectroscopy and computational chemistry.
► While ArgGly exclusively yields diketopiperazine structures, a mixture of diketopiperazine and oxazolone structures are confirmed for GlyArg.
► Product structures due to nucleophilic attacks from the guanidine side chain can be excluded.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Mass Spectrometry - Volumes 316–318, 15 April 2012, Pages 12–17
نویسندگان
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