scholarly journals The inhibition of glutamate dehydrogenase by l-serine O-sulphate and related compounds and by photo-oxidation in the presence of Rose Bengal

1971 ◽  
Vol 123 (3) ◽  
pp. 421-426 ◽  
Author(s):  
N. Tudball ◽  
P. Thomas
Keyword(s):  
Amino Acid ◽  
Methyl Ester ◽  
Glutamate Dehydrogenase ◽  
Rose Bengal ◽  
Amino Acid Analysis ◽  
Inhibitory Effects ◽  
Irreversible Inhibitor ◽  
Photo Oxidation ◽  
Rapid Inactivation ◽  
Related Compounds

1. Glutamate dehydrogenase was inhibited by l-serine O-sulphate, β-chloro-l-alanine, O-phospho-l-serine and β-chloro-l-alanine methyl ester. With the exception of β-chloro-l-alanine methyl ester which was an irreversible inhibitor, it was possible to reverse the inhibitory effects by dialysis. 2. Both NAD+ and glutamate afford some protection against the inhibition due to the methyl ester. No change in the normal stimulatory effect exhibited by ADP was observed in the presence of β-chloro-l-alanine methyl ester but the effect due to GTP was modified. 3. Irradiation of glutamate dehydrogenase in the presence of Rose Bengal produced rapid inactivation. Amino acid analysis of the inactivated enzyme showed that eight histidine residues had been destroyed in the process.

The action of rennin on casein: the effect of modifying functional groups on the casein

1965 ◽  
Vol 32 (2) ◽  
pp. 193-201 ◽  
Author(s):  
R. D. Hill ◽  
Raione R. Laing
Keyword(s):  
Methylene Blue ◽  
Amino Acid ◽  
Functional Groups ◽  
Amino Acid Analysis ◽  
Side Chains ◽  
Photo Oxidation

Summaryk-Casein and whole casein when photo-oxidized in the presence of methylene blue lose the ability to clot when treated with rennin. Two effects are involved—first the photo-oxidation alters the k-casein fraction so that the rennin is unable to split off the glycopeptide fragment, and secondly, in whole casein the photo-oxidation interferes with the aggregation in the presence of Ca++that normally follows rennin action. As a result of amino acid analysis and specific treatments which affect other photo-oxidizable side chains, it is concluded that both of these effects are caused by the alteration of histidines.

scholarly journals The enzymic degradation of l-serine O-sulphate. Mechanism of the reaction

1972 ◽  
Vol 128 (1) ◽  
pp. 41-46 ◽  
Author(s):  
N. Tudball ◽  
P. Thomas
Keyword(s):  
Hydrogen Atom ◽  
Carbon Atom ◽  
Rose Bengal ◽  
Incubation Medium ◽  
Tritiated Water ◽  
Competitive Inhibitor ◽  
Histidine Residues ◽  
Photo Oxidation ◽  
Rapid Inactivation ◽  
Mechanism Of The Reaction

1. During the enzyme-catalysed degradation of l-serine O-sulphate no exchange occurs between the hydrogen atom attached to the α-carbon atom of the substrate and the tritiated water of the incubation medium. 2. The participation of an intermediate carbanion has been demonstrated in the degradation by performing the reaction in the presence of tetranitromethane. 3. Photo-oxidation of the enzyme in the presence of Rose Bengal led to a rapid inactivation of enzyme with the concomitant loss of four histidine residues/molecule. 4. Rose Bengal was also a non-competitive inhibitor of the enzyme.

scholarly journals Isolation and nature of intracellular peptides from a cephalosporin C-producing Cephalosporium sp

1971 ◽  
Vol 123 (3) ◽  
pp. 471-476 ◽  
Author(s):  
P. Bronwen Loder ◽  
E. P. Abraham
Keyword(s):  
Mass Spectrum ◽  
Amino Acid ◽  
Methyl Ester ◽  
Amino Acid Analysis ◽  
Paper Electrophoresis ◽  
Sulphonic Acid ◽  
Cephalosporin C ◽  
Acid Form ◽  
The Third ◽  
Thiol Form

1. Three peptides containing α-aminoadipic acid and cysteine have been obtained in small amounts from the mycelium of a Cephalosporium sp. 2. The peptides were precipitated as cuprous mercaptides together with glutathione and resolved from the latter and from each other by preparative paper electrophoresis and chromatography either in the sulphonic acid form or as S-sulphonyl derivatives. From the S-sulphonyl derivatives they were obtained in the thiol form. 3. One peptide (P3) was shown by amino acid analysis and the mass spectrum of the NS-ethoxycarbonyl derivative of its methyl ester to be δ-(l-α-aminoadipyl)-l-cysteinyl-d-valine. A second peptide (P2) contained α-aminoadipic acid, cysteine, valine and glycine, and the third peptide (P1) contained α-aminoadipic acid, cysteine, β-hydroxyvaline and glycine.

Isolation and identification of some photo-oxidation products of tryptophan

1971 ◽  
Vol 24 (6) ◽  
pp. 1285 ◽  
Author(s):  
WE Savige
Keyword(s):  
Aqueous Solution ◽  
Amino Acid ◽  
Methyl Ester ◽  
Visible Light ◽  
Major Product ◽  
The Other ◽  
Oxidation Products ◽  
Isolation And Identification ◽  
Photo Oxidation ◽  
Tryptophan Methyl Ester

When an aerated aqueous solution of tryptophan at pH 6-9 is irradiated by visible light in the presence of a photosensitizing dye, N?- formylkynurenine is usually a major product. However, a similar irradiation in dilute ammonia at pH 8-9 gives mainly 4-(2-amino-2- carboxyethyl)quinazoline, a new amino acid; formyl-kynurenine 1s shown not to be an intermediate in the photoreaction. Tryptophan methyl ester and 2-methyltryptophan give photoproducts analogous to those of tryptophan. On the other hand, N-acetyltryptophan and indole-3- propionic acid give the formylkynurenine analogue either in the absence or presence of ammonia, no quinazoline being detected.

An ESR study of the peroxidase reaction catalyzed by human methaemoglobin and methaemoglobin-haptoglobin complex

1991 ◽  
Vol 56 (4) ◽  
pp. 923-932
Author(s):  
Jana Stejskalová ◽  
Pavel Stopka ◽  
Zdeněk Pavlíček
Keyword(s):  
Hydrogen Peroxide ◽  
Ascorbic Acid ◽  
Amino Acid ◽  
Peroxidase Activity ◽  
Amino Acid Analysis ◽  
Superoxide Radical ◽  
Esr Spectra ◽  
The Other ◽  
Delocalized Electron

The ESR spectra of peroxidase systems of methaemoglobin-ascorbic acid-hydrogen peroxide and methaemoglobin-haptoglobin complex-ascorbic acid-hydrogen peroxide have been measured in the acetate buffer of pH 4.5. For the system with methaemoglobin an asymmetrical signal with g ~ 2 has been observed which is interpreted as the perpendicular region of anisotropic spectrum of superoxide radical. On the other hand, for the system with methaemoglobin-haptoglobin complex the observed signal with g ~ 2 is symmetrical and is interpreted as a signal of delocalized electron. After realization of three repeatedly induced peroxidase processes the ESR signal of the perpendicular part of anisotropic spectrum of superoxide radical is distinctly diminished, whereas the signal of delocalized electron remains practically unchanged. An amino acid analysis of methaemoglobin along with results of the ESR measurements make it possible to derive a hypothesis about the role of haptoglobin in increasing of the peroxidase activity of methaemoglobin.

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