Chitosans were successfully characterized by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS). By the use of 2,5-dihydroxybenzoic acid as matrix and second-crystallized method...Chitosans were successfully characterized by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS). By the use of 2,5-dihydroxybenzoic acid as matrix and second-crystallized method for sample preparation, both the molecular weight and the degradation degrees of acetyl group of chitosan were obtained ,which were valuable for the preparation and quality control of chitosan.展开更多
Matrix assisted laser desorption / ionization time of flight (MALDI-TOF) mass spectrometry was used for The mass identification of tetrathiofulvalene compounds. Under The experimental conditions of MALDI-TOF, The samp...Matrix assisted laser desorption / ionization time of flight (MALDI-TOF) mass spectrometry was used for The mass identification of tetrathiofulvalene compounds. Under The experimental conditions of MALDI-TOF, The samples could be easily desorpted and ionized into single charge ions, The mass spectra with mono isotope resolution could be obtained. The mass analytical results of twenty-four compounds have shown that for The tetrathiofulvalene compounds MALDI-TOF is more effective, more convenient than other mass spectrometry methods.展开更多
Five major disaccharide peaks were obtained from the digests of heparin by a novel heparinase from the species of Sphingobacterium on the high performance liquid chromatography (HPLC). The electrospray ionization-mass...Five major disaccharide peaks were obtained from the digests of heparin by a novel heparinase from the species of Sphingobacterium on the high performance liquid chromatography (HPLC). The electrospray ionization-mass spectrometry of peak I to V sequentially represented one nonsulfated disaccharide, two monosulfated disaccharides,two disulfated disaccharides. No trisulfated disaccharide was detected. The findings revealed that the heparinase specifically eliminated undersulfated domain in heparin.展开更多
A new and sensitive method for the analysis of amino acids or oligopeptides has been developed by using transamination for fluorescence derivatization. Namely, α-amino group of amino acid or N-terminal amino group of...A new and sensitive method for the analysis of amino acids or oligopeptides has been developed by using transamination for fluorescence derivatization. Namely, α-amino group of amino acid or N-terminal amino group of oligopeptide was selectively converted into a highly reactive carbonyl group by transamination, and then coupled with 2,3-diaminonaphthalene to yield a fluorescent compound (a benzoquinoxaline derivative). The product was detected by fluorescence spectoscopy and electrospray mass spectrometry.The product is a polynuclear aromatic compound with a higher fluorescence quantum yield. It has an excitation and emission wavelength of 364nm and 514nm, respectively.The MS analysis confirmed the formation of the expected benzoquinoxaline derivative with a molecular ion peak at m/z268. The whole operation was conducted under mild conditions, and the method may be used to the sensitive detection of amino acids or peptides. It should be noted that some difficulties were encountered in the separation of the reaction products and the control of the reaction conditions, which need to be further improved.展开更多
文摘Chitosans were successfully characterized by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS). By the use of 2,5-dihydroxybenzoic acid as matrix and second-crystallized method for sample preparation, both the molecular weight and the degradation degrees of acetyl group of chitosan were obtained ,which were valuable for the preparation and quality control of chitosan.
文摘Matrix assisted laser desorption / ionization time of flight (MALDI-TOF) mass spectrometry was used for The mass identification of tetrathiofulvalene compounds. Under The experimental conditions of MALDI-TOF, The samples could be easily desorpted and ionized into single charge ions, The mass spectra with mono isotope resolution could be obtained. The mass analytical results of twenty-four compounds have shown that for The tetrathiofulvalene compounds MALDI-TOF is more effective, more convenient than other mass spectrometry methods.
文摘Five major disaccharide peaks were obtained from the digests of heparin by a novel heparinase from the species of Sphingobacterium on the high performance liquid chromatography (HPLC). The electrospray ionization-mass spectrometry of peak I to V sequentially represented one nonsulfated disaccharide, two monosulfated disaccharides,two disulfated disaccharides. No trisulfated disaccharide was detected. The findings revealed that the heparinase specifically eliminated undersulfated domain in heparin.
文摘A new and sensitive method for the analysis of amino acids or oligopeptides has been developed by using transamination for fluorescence derivatization. Namely, α-amino group of amino acid or N-terminal amino group of oligopeptide was selectively converted into a highly reactive carbonyl group by transamination, and then coupled with 2,3-diaminonaphthalene to yield a fluorescent compound (a benzoquinoxaline derivative). The product was detected by fluorescence spectoscopy and electrospray mass spectrometry.The product is a polynuclear aromatic compound with a higher fluorescence quantum yield. It has an excitation and emission wavelength of 364nm and 514nm, respectively.The MS analysis confirmed the formation of the expected benzoquinoxaline derivative with a molecular ion peak at m/z268. The whole operation was conducted under mild conditions, and the method may be used to the sensitive detection of amino acids or peptides. It should be noted that some difficulties were encountered in the separation of the reaction products and the control of the reaction conditions, which need to be further improved.
