Carboxypeptidase A catalysis of an .alpha.,.beta.-elimination reaction

1981 ◽  
Vol 103 (12) ◽  
pp. 3611-3612 ◽  
Author(s):  
N. T. Nashed ◽  
E. T. Kaiser
Keyword(s):  
Elimination Reaction ◽  
Carboxypeptidase A ◽  
Beta Elimination ◽  
Alpha Beta

scholarly journals Purification and characterization of human hepatic cysteine-conjugate β-lyase

1986 ◽  
Vol 235 (2) ◽  
pp. 569-575 ◽  
Author(s):  
H Tomisawa ◽  
S Ichihara ◽  
H Fukazawa ◽  
N Ichimoto ◽  
M Tateishi ◽  
...  
Keyword(s):  
Human Liver ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Elimination Reaction ◽  
Purification And Characterization ◽  
Ph Optimum ◽  
Beta Elimination ◽  
Alpha Beta ◽  
Hydroxyapatite Gel

Cysteine-conjugate beta-lyase (EC 4.4.1.13) was purified about 880-fold from human liver obtained post mortem. The purification procedure included (NH4)2SO4 precipitation, chromatography on DEAE-cellulose and hydroxyapatite, gel filtration on Sephadex G-200, and chromatofocusing. The purified enzyme cleaves the C-S bond of several S-aryl-L-cysteines to yield equimolar amounts of thiols, pyruvic acid and ammonia via an alpha beta-elimination reaction. The Mr of the enzyme was estimated to be 88,000 by gel filtration. The enzyme is thermolabile, has a pH optimum of 8.5, and an apparent Km of 0.7 mM towards S-(p-bromophenyl)-L-cysteine. The enzyme requires pyridoxal 5′-phosphate as a cofactor, and hence the enzyme activity was completely abolished by hydroxylamine. No effect of EDTA or thiol-blocking reagents was observed on the activity of the enzyme.

Wittig modification of the Hofmann elimination reaction. Evidence for an .alpha.',.beta. mechanism

1972 ◽  
Vol 94 (24) ◽  
pp. 8608-8610 ◽  
Author(s):  
Robert D. Bach ◽  
Kenneth W. Bair ◽  
Denis Andrzejewski
Keyword(s):  
Elimination Reaction ◽  
Alpha Beta ◽  
Hofmann Elimination

A first-order base-initiated .beta.-elimination reaction involving a carbanion intermediate

1970 ◽  
Vol 92 (20) ◽  
pp. 5945-5949 ◽  
Author(s):  
Frederick G. Bordwell ◽  
Kwok-Chun. Yee ◽  
A. C. Knipe
Keyword(s):  
Elimination Reaction ◽  
First Order ◽  
Beta Elimination

scholarly journals Bacteriophage-T4 and Micrococcus luteus UV endonucleases are not endonucleases but β-elimination and sometimes βδ-elimination catalysts

1989 ◽  
Vol 259 (3) ◽  
pp. 751-759 ◽  
Author(s):  
V Bailly ◽  
B Sente ◽  
W G Verly
Keyword(s):  
Enzyme Preparation ◽  
Micrococcus Luteus ◽  
Bacteriophage T4 ◽  
Pyrimidine Dimer ◽  
Elimination Reaction ◽  
Ap Sites ◽  
Beta Elimination ◽  
Ap Site ◽  
Polynucleotide Chain

Bacteriophage-T4 UV endonuclease nicks the C(3′)-O-P bond 3′ to AP (apurinic or apyrimidinic) sites by a beta-elimination reaction. The breakage of this bond is sometimes followed by the nicking of the C(5′)-O-P bond 5′ to the AP site, leaving a 3′-phosphate end; delta-elimination is proposed as a mechanism to explain this second reaction. The AP site formed when this enzyme acts on a pyrimidine dimer in a polynucleotide chain undergoes the same nicking reactions. Micrococcus luteus UV endonuclease also nicks the C(3′)-O-P bond 3′ to AP sites by a beta-elimination reaction. No subsequent delta-elimination was observed, but this might be due to the presence of 2-mercaptoethanol in the enzyme preparation.

ChemInform Abstract: THE BASE-INDUCED BETA-ELIMINATION REACTION OF 1,1,1-TRISUBSTITUTED HYDRAZINIUM SALTS

1974 ◽  
Vol 5 (37) ◽  
pp. no-no
Author(s):  
Y. TAMURA ◽  
J. MINAMIKAWA ◽  
O. NISHIKAWA ◽  
M. IKEDA
Keyword(s):  
Elimination Reaction ◽  
Beta Elimination ◽  
Hydrazinium Salts

scholarly journals Rapid and selective modification of phosphoserine residues catalysed by Ba2+ ions for their detection during peptide microsequencing

1991 ◽  
Vol 280 (1) ◽  
pp. 261-265 ◽  
Author(s):  
M F Byford
Keyword(s):  
Amino Acid ◽  
Sequence Analysis ◽  
Metal Ions ◽  
Ion Concentration ◽  
Thiol Groups ◽  
Disulphide Bonds ◽  
Rate Of Reaction ◽  
Alkaline Conditions ◽  
Beta Elimination ◽  
Alpha Beta

The beta-elimination of phosphoserine residues by dilute alkali is catalysed by the presence of group II metal ions. The use of 0.1 M-Ba (OH)2 catalysed the rate of beta-elimination of phosphoserine by more than two orders of magnitude compared with the use of NaOH at the same OH-ion concentration. Serine and threonine residues are unaffected by this treatment. Free thiol groups and disulphide bonds are labile to these conditions, but carboxymethylcysteine is stable. The rate of beta-elimination of O-glycosidically linked moieties is not catalysed under these conditions, and the rate of reaction is thus two orders of magnitude slower than for phosphoserine. This specific catalysis was readily exploited in the rapid and selective modification of phosphoserine residues under mildly alkaline conditions with the nucleophile methylamine via the alpha beta-desaturated dehydroalanine intermediate to yield the beta-methylaminoalanine residue. This modified residue could be easily detected on sequence analysis and in amino acid compositions.

Sign in / Sign up

Export Citation Format

Share Document