The reaction of 4-Amino-5-aminomethyl-2-methylpyrimidine with amidine salts

1973 ◽  
Vol 26 (7) ◽  
pp. 1599 ◽  
Author(s):  
RF Evans ◽  
AV Robertson
Keyword(s):  
Structure Determination ◽  
Mass Spectra ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Fragmentation Process ◽  
Spectrometric Analysis ◽  
Present Structure

Treatment of 4-amino-5-aminomethyl-2-methylpyrimidine with formamidine salts yields not the expected dihydropyrimidopyrimidine, but rather its ring-opened hydrate, 4-amino-5-formamidomethyl-2-methylpyrimidine. Other workers had previously prepared the latter compound by other methods, but had assigned a wrong structure. The present structure determination is based mainly on i.r., N.M.R., and mass spectrometric analysis, as well as examination of the corresponding acetamido series. Mass spectra include a noteworthy fragmentation process, expulsion of neutral, even-electron NH.

scholarly journals Identification of post-translational modifications resulting from LHbeta polymorphisms by matrix-assisted laser desorption time-of-flight mass spectrometric analysis of pituitary LHbeta core fragment

2003 ◽  
Vol 30 (2) ◽  
pp. 239-252 ◽  
Author(s):  
ES Jacoby ◽  
AT Kicman ◽  
RK Iles
Keyword(s):  
Mass Spectra ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Spectrometric Analysis ◽  
Core Fragment ◽  
Peptide Mass ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

Metabolism of the human chorionic gonadotrophin (hCG)- and LHbeta-subunits (hCGbeta, LHbeta) terminates with the urinary excretion of core fragment (hCGbetacf, LHbetacf) molecules that retain antigenic shape and constituent N-linked carbohydrate moieties. We have previously demonstrated the resolved mass spectra of hCGbetacf, from which the carbohydrate moieties present at two N-linked glycosylation sites were identified. LHbetacf was subjected to the same mass spectrometric analysis. As LHbeta shares 82% homology with hCGbeta but possesses only one glycosylation consensus site a simpler spectral fingerprint of LHbetacf glycoforms was expected. LHbetacf was reduced with dithiothreitol and analysed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. Glycoforms were predicted by subtracting the peptide mass from the m/z values of the observed peaks and then sequentially subtracting the masses of the monosaccharide residues of hCGbeta N-linked carbohydrates reported in the literature. The mass spectra of LHbetacf revealed a broad single peak ranging from m/z 8700 to 10 700. Following reduction, this peak was replaced by a set of partially resolved peaks between m/z 4130 and 5205 corresponding to glycosylated forms of the peptide LHbeta6-40. A peak at m/z 4252.2 corresponded to the non-glycosylated peptide LHbeta55-93. Remaining peaks indicated that the pooled sample comprised a wide set of glycoforms, contained LHbetacf with two N-linked carbohydrate moieties and indicated evidence of further glycosylation due to amino acid substitution in polymorphic variants. This is evidence that a single nucleotide polymorphism alters the post-translational modification of a protein and hence its structural phenotype.

scholarly journals Serendipitous crystallization and structure determination of cyanase (CynS) fromSerratia proteamaculans

2015 ◽  
Vol 71 (4) ◽  
pp. 471-476 ◽  
Author(s):  
Agata Butryn ◽  
Gabriele Stoehr ◽  
Christian Linke-Winnebeck ◽  
Karl-Peter Hopfner
Keyword(s):  
Escherichia Coli ◽  
Carbon Dioxide ◽  
Structure Determination ◽  
Active Site ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Spectrometric Analysis ◽  
Conserved Residues ◽  
Serratia Proteamaculans

Cyanate hydratase (CynS) catalyzes the decomposition of cyanate and bicarbonate into ammonia and carbon dioxide. Here, the serendipitous crystallization of CynS fromSerratia proteamaculans(SpCynS) is reported. SpCynS was crystallized as an impurity and its identity was determined using mass-spectrometric analysis. The crystals belonged to space groupP1 and diffracted to 2.1 Å resolution. The overall structure of SpCynS is very similar to a previously determined structure of CynS fromEscherichia coli. Density for a ligand bound to the SpCynS active site was observed, but could not be unambiguously identified. Additionally, glycerol molecules bound at the entry to the active site of the enzyme indicate conserved residues that might be important for the trafficking of substrates and products.

Mass spectrometric analysis of the products from the isotopomeric cationic intermediates in the solvolysis of 1,2-dianisyl-2-p-(2H3)methoxyphenyl[2-13C]vinyl bromide in 70% HOAc – 30% H2O

1983 ◽  
Vol 61 (9) ◽  
pp. 2159-2164
Author(s):  
Choi Chuck Lee ◽  
Xian-Da Yu ◽  
Charles Y. Fiakpui
Keyword(s):  
Mass Spectra ◽  
Chemical Ionization ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Spectrometric Analysis ◽  
Reaction Products ◽  
Ionization Technique ◽  
Vinyl Bromide ◽  
C Nmr

Solvolyses were carried out with 6.0 mM doubly labeled 1,2-dianisyl-2-p-(2H3)methoxyphenyl[2-13C]vinyl bromide in 70% HOAc – 30% H2O in the presence of 0, 1, 5, 10, or 400 molar equivalents of added NaOAc. The distributions of products derived from the 4 possible isotopomeric trianisylvinyl cationic intermediates were determined from the mass spectra of the isotopomeric dianisyl ketones obtained from degradation of the reaction products, the spectra being obtained by the chemical ionization technique in order to minimize possible complications by multiple fragmentations. The mass spectrometrie results obtained showed agreement with previously obtained 14C scrambling data and with the 13C scramblings obtained in the present study using 13C nmr. Increasing amounts of added NaOAc had the effect of decreasing the extents of scrambling from 1,2-anisyl shifts as previously observed. However, the formation of products from all 4 possible doubly labeled isotopomeric trianisylvinyl cations definitely demonstrated the occurrence of successive 1,2-anisyl shifts in the trianisylvinyl cation, and the detection of such successive shifts was not possible in previous work using a singly labeled substrate. The observed distribution of products derived from the 4 isotopomeric cations could be calculated assuming various contributions from equilibrations among these isotopomeric cations, and the mechanistic implications of the results are discussed.

scholarly journals Benzodiazepine Analogues. Part 20. Mass Spectrometric Analysis of Benzoxathiepine Derivatives

1999 ◽  
Vol 23 (9) ◽  
pp. 584-585
Author(s):  
Aifheli C. Gelebe ◽  
Perry T. Kaye
Keyword(s):  
High Resolution ◽  
Electron Impact ◽  
Mass Spectra ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Spectrometric Analysis ◽  
Low Resolution ◽  
Fragmentation Patterns ◽  
Resolution Mass

Fragmentation patterns in the electron-impact (El) mass spectra of benzoxathiepine derivatives are elucidated using a combination of high-resolution and comparative low-resolution mass spectrometric analysis.

A Questionnaire Survey on General Status and Opinions about Clinical Mass Spectrometric Analysis in Korea (2018)

2019 ◽  
Vol 9 (3) ◽  
pp. 161
Author(s):  
Sung-Eun Cho ◽  
Hyojin Chae ◽  
Hyung-Doo Park ◽  
Sail Chun ◽  
Yong-Wha Lee ◽  
...  
Keyword(s):  
Questionnaire Survey ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Spectrometric Analysis ◽  
General Status

Mechanisms of Dopant Depth Profile Modification During Mass Spectrometric Analysis of Multilayer Structure

2015 ◽  
Vol 60 (6) ◽  
pp. 511-520 ◽  
Author(s):  
A.A. Efremov ◽  
◽  
V.G. Litovchenko ◽  
V.P. Melnik ◽  
O.S. Oberemok ◽  
...  
Keyword(s):  
Depth Profile ◽  
Multilayer Structure ◽  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Spectrometric Analysis ◽  
Profile Modification

Mass Spectrometric Analysis of Porcine Rhodopsin¶

2002 ◽  
Vol 75 (3) ◽  
pp. 316 ◽  
Author(s):  
Zsolt Ablonczy ◽  
Patrice Goletz ◽  
Daniel R. Knapp ◽  
Rosalie K. Crouch
Keyword(s):  
Mass Spectrometric ◽  
Mass Spectrometric Analysis ◽  
Spectrometric Analysis
Sign in / Sign up

Export Citation Format

Share Document