“…It should be pointed out that 9,lO-dihydrophenantrene-type structures of the molecule ions a of 1-16 shown in Schemes 1-3 are conjectural, but consistent with previously published literature data.l6sI7 The principal mass fragmentation pathways of N-substituted amino acids (3,6,9,12,15,17,19) are similar to those of their metameric methyl esters (1, 4, 7, 10, 13, 16, 18) and hydrazides (2, 5, 8,11,14) but show differences in the abundances of the important ions.…”
Section: Rwults and Discussionsupporting
confidence: 85%
“…N-substituted a-alanine (3) and P-phenyl-P-alanine (6, 9, 17, 19) may be distinguished from metameric methyl esters (1 and 4, 7, 16, 18 The methyl esters of N-substituted P-phenyl-P-alanines (4, 7) may be distinguished from their metameric Of P I . N-Substituted tryptophans (12, 15) may be distinguished from their metameric methyl esters (10, 13) and hydrazides (11,14) on the basis of the lowest values of p3. The hydrazides of N-substituted tryptophan (11,14) may be distinguished from their metameric Nsubstituted amino acids and methyl esters (10, 12, 13, 15) on the basis of the highest values of p,, p2 and p3.…”
Section: (Iii) In the Series Of Metameric N-substituted Fl-mentioning
confidence: 99%
“…N-Substituted tryptophans (12, 15) may be distinguished from their metameric methyl esters (10, 13) and hydrazides (11,14) on the basis of the lowest values of p3. The hydrazides of N-substituted tryptophan (11,14) may be distinguished from their metameric Nsubstituted amino acids and methyl esters (10, 12, 13, 15) on the basis of the highest values of p,, p2 and p3.…”
Section: (Iii) In the Series Of Metameric N-substituted Fl-mentioning
confidence: 99%
“…The values of p,-pr calculated from the EI mass spectra recorded at 75 eV (15 eV)P of N-(E)stilbenyloxyalkylcarbonyl-substituted a-alanine (3) and fbphenyl-Palanines (6, 9) and their metameric methyl esters (1, 4, 7) and hydrazides (2, 5, 8) and of N-(E)-stilbenyloxyalkylcarbonylsubstituted tryptophan (12, 15) and their metameric methyl esters (10, 13) and hydrazides(11,14) and of N-(E)-stilbenyloxyalkylcarbonyl-substituted /I-phenyl-/I-alanines(17,19) and their metameric methyl esters(16,18) …”
The mass spectral fragmentations of nineteen new metameric N-(E)-stilbenyloxyalkylcarboayl-[or (E)4'chlorostilbenyloxyalkylcarbonyl)~ -substituted amino acids and their metameric methyl esters and hydrazides were investigated. Fragmentation pathways are proposed on the basis of accurate mass and metastable transition measurements. The correlation between the intensities of M+' and the selected fragment ions of these compounds is discussed. The data obtained create the basis for distinguishing metamers.
“…It should be pointed out that 9,lO-dihydrophenantrene-type structures of the molecule ions a of 1-16 shown in Schemes 1-3 are conjectural, but consistent with previously published literature data.l6sI7 The principal mass fragmentation pathways of N-substituted amino acids (3,6,9,12,15,17,19) are similar to those of their metameric methyl esters (1, 4, 7, 10, 13, 16, 18) and hydrazides (2, 5, 8,11,14) but show differences in the abundances of the important ions.…”
Section: Rwults and Discussionsupporting
confidence: 85%
“…N-substituted a-alanine (3) and P-phenyl-P-alanine (6, 9, 17, 19) may be distinguished from metameric methyl esters (1 and 4, 7, 16, 18 The methyl esters of N-substituted P-phenyl-P-alanines (4, 7) may be distinguished from their metameric Of P I . N-Substituted tryptophans (12, 15) may be distinguished from their metameric methyl esters (10, 13) and hydrazides (11,14) on the basis of the lowest values of p3. The hydrazides of N-substituted tryptophan (11,14) may be distinguished from their metameric Nsubstituted amino acids and methyl esters (10, 12, 13, 15) on the basis of the highest values of p,, p2 and p3.…”
Section: (Iii) In the Series Of Metameric N-substituted Fl-mentioning
confidence: 99%
“…N-Substituted tryptophans (12, 15) may be distinguished from their metameric methyl esters (10, 13) and hydrazides (11,14) on the basis of the lowest values of p3. The hydrazides of N-substituted tryptophan (11,14) may be distinguished from their metameric Nsubstituted amino acids and methyl esters (10, 12, 13, 15) on the basis of the highest values of p,, p2 and p3.…”
Section: (Iii) In the Series Of Metameric N-substituted Fl-mentioning
confidence: 99%
“…The values of p,-pr calculated from the EI mass spectra recorded at 75 eV (15 eV)P of N-(E)stilbenyloxyalkylcarbonyl-substituted a-alanine (3) and fbphenyl-Palanines (6, 9) and their metameric methyl esters (1, 4, 7) and hydrazides (2, 5, 8) and of N-(E)-stilbenyloxyalkylcarbonylsubstituted tryptophan (12, 15) and their metameric methyl esters (10, 13) and hydrazides(11,14) and of N-(E)-stilbenyloxyalkylcarbonyl-substituted /I-phenyl-/I-alanines(17,19) and their metameric methyl esters(16,18) …”
The mass spectral fragmentations of nineteen new metameric N-(E)-stilbenyloxyalkylcarboayl-[or (E)4'chlorostilbenyloxyalkylcarbonyl)~ -substituted amino acids and their metameric methyl esters and hydrazides were investigated. Fragmentation pathways are proposed on the basis of accurate mass and metastable transition measurements. The correlation between the intensities of M+' and the selected fragment ions of these compounds is discussed. The data obtained create the basis for distinguishing metamers.
“…M ass spectrometry has found increasing use as a tool for analyzing the sequence of amino acids in peptides (Biemann et al, 1966;Shemyakin et a/., 1966;Thomas et a/., 1968). Apart from a few instances where it has been applied to peptides isolated from proteins (Geddes et NI., 1969) the method has been used principally upon synthetic peptides of known structure or on peptide antibiotics.…”
The N-acetyl-, N-trifluoroacetyl-, N-pentafluoropropioayl-and N-heptafluorobutylamino derivatives of the tripeptide valyl-alanyl-leucine have been synthesized in every combination with the carboxy derivatives O-methyl ester, O-(l-H,H)-trifluoroethyI ester, 041-H,H)-pentafluoropropyl ester and 041-H,H)-heptafluorobutyl ester. These 16 derivatives have been mass measured after negative ionization using a 10% CO,/Ar moderator gas mixture in an electron impact ion source of a VGZAB2F mass spectrometer. The fragmentation behaviour of the peptide derivatives have been studied by negative linked-scan, negative mass-analysed ion kinetic energy and charge inversion mass spectrometry. Mast detected sequence ions originate from N-terminal fragments. Recorded anion currents and linked-scan measurement have shown that fluoro residues at the C-terminus increase the intensities of sequence ions, whereas N-terminal perfhoroalkyl derivatives generate [M -HFI-and [M -2HFl-ions. The abundances of these fragment ions increase with increasing molecular weight of the N-terminal residues. The best sequence information with intense anion currents has been recorded with the peptide derivative Ntrifluoroacetylarnino-0-hepatafluorobutyl ester.
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