Ammonolysis of cephamycins: carbon-13 NMR characterization of the intermediates from .beta.-lactam ring cleavage prior to loss of the 3'-group

1985 ◽  
Vol 107 (1) ◽  
pp. 267-268 ◽  
Author(s):  
E. J. J. Grabowski ◽  
A. W. Douglas ◽  
G. B. Smith
Keyword(s):  
Ring Cleavage ◽  
Beta Lactam ◽  
Nmr Characterization ◽  
Lactam Ring

Molecular Orbital Study of Reaction Processes in the Thermospray Mass Spectra of Deuterated Penicillins

1989 ◽  
Vol 43 (7) ◽  
pp. 1215-1222
Author(s):  
Marshall M. Siegel ◽  
Norman B. Colthup
Keyword(s):  
Molecular Orbital ◽  
Mass Spectra ◽  
Ring Cleavage ◽  
Molecular Orbital Calculations ◽  
Proton Affinities ◽  
Beta Lactam ◽  
Fragment Ions ◽  
Lactam Ring ◽  
Hydrogen Deuterium ◽  
Reaction Processes

Mass spectra of penicillin compounds were generated with the use of a thermospray mass spectrometer interface and deuterated solvents. Deuterium ion addition sites to the parent ion and the substituted ketene and thiazoline fragment ions were investigated with the use of molecular orbital calculations for computing the relative proton affinities for the various ion isomers. The energetics of the beta-lactam ring cleavage, which generates the fragment ions, were calculated, as well as the energetics of various C-H to C-D hydrogen-deuterium exchange processes, which generate the substituted ketene fragment ions. The calculations afforded the identification of the most probable structures for the generated ions.

NMR characterization of complex natural products: Assigning novel, proton-deficient alkaloid scaffolds

Planta Medica ◽  
2016 ◽  
Vol 81 (S 01) ◽  
pp. S1-S381
Author(s):  
KR Gustafson ◽  
STS Chan ◽  
D Milanowski
Keyword(s):  
Natural Products ◽  
Nmr Characterization

Synthesis and 31 P NMR characterization of new low toxic highly sensitive pH probes designed for in vivo acidic pH studies

2002 ◽  
Vol 10 (5) ◽  
pp. 1451-1458 ◽  
Author(s):  
Sophie Martel ◽  
Jean-Louis Clément ◽  
Agnès Muller ◽  
Marcel Culcasi ◽  
Sylvia Pietri
Keyword(s):  
Acidic Ph ◽  
Highly Sensitive ◽  
Nmr Characterization ◽  
Low Toxic ◽  
Ph Probes

scholarly journals Characterization of the Gallate Dioxygenase Gene: Three Distinct Ring Cleavage Dioxygenases Are Involved in Syringate Degradation by Sphingomonas paucimobilis SYK-6

2005 ◽  
Vol 187 (15) ◽  
pp. 5067-5074 ◽  
Author(s):  
Daisuke Kasai ◽  
Eiji Masai ◽  
Keisuke Miyauchi ◽  
Yoshihiro Katayama ◽  
Masao Fukuda
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequences ◽  
Terminal Region ◽  
Ring Cleavage ◽  
Sphingomonas Paucimobilis ◽  
Acid Protein ◽  
Demethylation Pathway ◽  
Dioxygenase Gene ◽  
Amino Acid Protein

ABSTRACT Sphingomonas paucimobilis SYK-6 converts vanillate and syringate to protocatechuate (PCA) and 3-O-methylgallate (3MGA) in reactions with the tetrahydrofolate-dependent O-demethylases LigM and DesA, respectively. PCA is further degraded via the PCA 4,5-cleavage pathway, whereas 3MGA is metabolized via three distinct pathways in which PCA 4,5-dioxygenase (LigAB), 3MGA 3,4-dioxygenase (DesZ), and 3MGA O-demethylase (LigM) are involved. In the 3MGA O-demethylation pathway, LigM converts 3MGA to gallate, and the resulting gallate appears to be degraded by a dioxygenase other than LigAB or DesZ. Here, we isolated the gallate dioxygenase gene, desB, which encodes a 418-amino-acid protein with a molecular mass of 46,843 Da. The amino acid sequences of the N-terminal region (residues 1 to 285) and the C-terminal region (residues 286 to 418) of DesB exhibited ca. 40% and 27% identity with the sequences of the PCA 4,5-dioxygenase β and α subunits, respectively. DesB produced in Escherichia coli was purified and was estimated to be a homodimer (86 kDa). DesB specifically attacked gallate to generate 4-oxalomesaconate as the reaction product. The Km for gallate and the V max were determined to be 66.9 ± 9.3 μM and 42.7 ± 2.4 U/mg, respectively. On the basis of the analysis of various SYK-6 mutants lacking the genes involved in syringate degradation, we concluded that (i) all of the three-ring cleavage dioxygenases are involved in syringate catabolism, (ii) the pathway involving LigM and DesB plays an especially important role in the growth of SYK-6 on syringate, and (iii) DesB and LigAB are involved in gallate degradation.

Sign in / Sign up

Export Citation Format

Share Document