78887-39-5Relevant articles and documents
Probing of arginine residues in peptides and proteins using selective tagging and electrospray ionization mass spectrometry
Leitner, Alexander,Lindner, Wolfgang
, p. 891 - 899 (2003)
A general labelling method is presented which allows the determination of the number of guanidine groups (related to arginine and homoarginine in peptides and proteins) by means of mass spectrometry. It implies a guanidine-selective derivatization step with 2,3-butanedione and an arylboronic acid under aqueous, alkaline conditions (pH 8-10). The reaction mixture is then directly analysed by electrospray ionization mass spectrometry without further sample pretreatment. Other amino acids are not affected by this reaction although it is demonstrated that lysine side-chains may be unambiguously identified when they are converted to homoarginine prior to derivatization. Guanidine functionalities, as e.g. in the amino acid arginine, are easily identified by the characteristic mass shift between underivatized and derivatized analyte. The tagging procedure is straightforward and selective for guanidine groups. The influence of several experimental parameters, especially the pH of the solution and the choice of reagents, is examined and the method is applied to various arginine-containing peptides and to lysozyme as a representative protein. Possible applications of this technique and its limitations are discussed. Copyright
Synthetic studies connected with the preparation of N-[3-(3- cyanopyrazolo[1,5-a]pyrimidin-5-yl)phenyl]-N-ethylacetamide, a zaleplon regioisomer
Radl, Stanislav,Blahovcova, Michaela,Tkadlecova, Marcela,Havlicek, Jaroslav
experimental part, p. 1359 - 1376 (2010/10/20)
N-[3-(3-Cyanopyrazolo[1,5-a]pyrimidin-5-yl)phenyl]-N-ethyl-acetamide, a principal impurity of zaleplon, is prepared by Suzuki-Miyaura cross coupling reaction of the corresponding boronic acid and/or boronates with 5-chloropyrazolo[1,5-a]pyrimidin-3-carbonitrile (7). Various methods of preparation of both components are described, as well as approaches based on the final modification of the 5-(3-aminophenyl)-pyrazolo[1,5-a]pyrimidine-3- carbonitrile moiety prepared by Suzuki-Miyaura cross coupling. All the prepared compounds were unambiguouesly identified by NMR techniques. Spectral characteristics (IR, UV, MS) of these compounds are also given.
Re-investigation of optical sensing properties of boronic-acid-appended ReI complexes for saccharides
Mizuno, Toshihisa,Fukumatsu, Takayuki,Takeuchi, Masayuki,Shinkai, Seiji
, p. 407 - 413 (2007/10/03)
A number of unanswered questions occurred to us upon reading a communication by Yam and Kai (ref. 16) which had reported optical sensing properties of a boronic-acid-appended ReI complex for saccharides. Careful re-examination has disclosed that the pKa-value proposed by them (5.9) is wrong and that the saccharide-binding mode at pH above the pKa is totally different from that at pH below the pKa. The absorption spectral change, which reflects an sp2-to-sp3 boron hybridisation change induced by the saccharide complexation, was observed only at pH below the pKa, and the CD band, which reflects the formation of 1:1 cyclic complexes, appeared only at pH above the pKa. The results imply that the optimum pH should be carefully selected for the precise optical sensing of saccharides.
