Peculiarities of 2,6-Di-tert-butylpyridine Protonation: Mobility of Protonated Molecules

2021 ◽  
Vol 76 (13) ◽  
pp. 1538-1548
Author(s):  
A. V. Lebedev
Keyword(s):  
Protonated Molecules

scholarly journals The collisional behavior of ESI-generated protonated molecules of some carbamate FAAH inhibitors isosteres and its relationships with biological activity

2008 ◽  
Vol 44 (4) ◽  
pp. 561-565 ◽  
Author(s):  
Giovanni Valitutti ◽  
Andrea Duranti ◽  
Marco Mor ◽  
Giovanni Piersanti ◽  
Daniele Piomelli ◽  
...  
Keyword(s):  
Biological Activity ◽  
Faah Inhibitors ◽  
Protonated Molecules

scholarly journals Orientational Analysis of Monolayers at Low Surface Concentrations Due to an Increased Signal-to-Noise Ratio (S/N) Using Broadband Sum Frequency Generation Vibrational Spectroscopy

2019 ◽  
Vol 73 (10) ◽  
pp. 1146-1159 ◽  
Author(s):  
Narendra M. Adhikari ◽  
Uvinduni I. Premadasa ◽  
Zachary J. Rudy ◽  
Katherine Leslee A. Cimatu
Keyword(s):  
Tilt Angle ◽  
Signal To Noise Ratio ◽  
Sum Frequency Generation ◽  
Ambient Conditions ◽  
Signal To Noise ◽  
Sum Frequency ◽  
Low Concentrations ◽  
Assembled Monolayers ◽  
Frequency Generation ◽  
Protonated Molecules

Sum frequency generation (SFG) * Equal contributors. spectroscopy was used to deduce the orientation of the terminal methyl (CH3) group of self-assembled monolayers (SAMs) at the air–solid and air–liquid interfaces at surface concentrations as low as 1% protonated molecules in the presence of 99% deuterated molecules. The SFG spectra of octadecanethiol (ODT) and deuterated octadecanethiol (d37 ODT) SAMs on gold were used for analysis at the air–solid interface. However, the eicosanoic acid (EA) and deuterated EA (d39 EA) SAMs on the water were analyzed at the air–liquid interface. The tilt angle of the terminal CH3 group was estimated to be ∼39 ° for a SAM of 1% ODT : 99% d37 ODT, whereas the tilt angle of the terminal CH3 group of the 1% EA : 99% d39 EA monolayer was estimated to be ∼32 °. The reliability of the orientational analysis at low concentrations was validated by testing the sensitivity of the SFG spectroscopy. A signal-to-noise (S/N) ratio of ∼60 and ∼45 was obtained for the CH3 symmetric stretch (SS) of 1% ODT : 99% d37 ODT and 1% EA : 99% d39 EA, respectively. The estimated increase in S/N ratio values, as a measure of the sensitivity of the SFG spectroscopy, verified the capacity to acquire the SFG spectra at low concentrations of interfacial molecules under ambient conditions. Overall, the orientational analysis of CH3 SS vibrational mode was feasible at low concentrations of protonated molecules due to increased S/N ratio. In support, the improved S/N ratio on varying incident power density of the visible beam was also experimentally demonstrated.

Strategy for Structure Elucidation of Drug Metabolites Derived from Protonated Molecules and (MS)n Fragmentation of Zotepine, Tiaramide and their Metabolites

2002 ◽  
Vol 17 (4) ◽  
pp. 316-339 ◽  
Author(s):  
Zenzaburo Tozuka ◽  
Hayato Kaneko ◽  
Toshifumi Shiraga ◽  
Yasuyuki Mitani ◽  
Akio Kawamura ◽  
...  
Keyword(s):  
Structure Elucidation ◽  
Drug Metabolites ◽  
Protonated Molecules

Side Reaction During the Deprotection of Cys(Acm)-Containing Peptides with Iodine. Synthesis of Disulfide Fragments from Cathepsin D Structure

1995 ◽  
Vol 60 (6) ◽  
pp. 1042-1049 ◽  
Author(s):  
Jan Ježek ◽  
Vlasta Velková ◽  
Václav Kašička ◽  
Zdeněk Prusík ◽  
Karel Ubik ◽  
...  
Keyword(s):  
Cathepsin D ◽  
Solid Phase ◽  
Side Reaction ◽  
Phase Method ◽  
Relative Molecular Mass ◽  
Zone Electrophoresis ◽  
Solid Phase Method ◽  
Capillary Zone ◽  
Protonated Molecules ◽  
Analytical Hplc

Peptides H-TPPQC(Acm)FTV-NH2 (I) and H-VSVPC(Acm)QSASSAS-NH2 (III) were prepared by the solid phase method. Their oxidation with iodine afforded hexadecapeptide II, tetracosapeptide IV and eicosapeptide VI. The disulfide peptides II, IV and VI are designed according to the sequence of the processing loop in human cathepsin D. The purity of the peptides was determined by analytical HPLC and capillary zone electrophoresis. In addition to the expected [M + H]+ ion, FAB MS of HPLC-pure tetracosapeptide IV exhibited a molecular ion with the same relative molecular mass as the starting dodecapeptide III, in spite of clean HPLC separation of III and IV. Free-flow zone electrophoresis of IV separated peptide V, isomeric with III. Mass spectra, amino acid analysis and Edman sequencing revealed that the peptide V is a product of iodine-mediated S-->O shift of Acm group in the serine-rich peptide III. Daughter-ion spectra of protonated molecules, recorded after collision-induced dissociation, have shown that the Acm moiety is bonded to Ser 9 or Ser 10.

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