L-Cysteinylglycine: its occurrence and identification

1970 ◽  
Vol 48 (9) ◽  
pp. 1029-1036 ◽  
Author(s):  
Russell Tkachuk
Keyword(s):  
Amino Acid ◽  
Human Serum ◽  
Mass Spectroscopy ◽  
Amino Acid Analysis ◽  
Wheat Germ ◽  
E Coli ◽  
Murine Tissue

L-Cysteinylglycine is present in wheat germ. The peptide was isolated as the S-carboxymethyl-2-14C derivative. The identity of S-carboxymethyl-L-cysteinylglycine was determined by amino acid analysis, N-terminal analysis, and mass spectroscopy. L-Cysteinylglycine appears to be widespread in nature as it is found also in E. coli, murine tissue, and human serum. It does not seem to be present in yeast.

γ-L-Glutamyl-L-cysteine: its isolation and identification from wheat germ

1977 ◽  
Vol 55 (4) ◽  
pp. 295-300 ◽  
Author(s):  
Russell Tkachuk ◽  
V. J. Mellish
Keyword(s):  
Amino Acid ◽  
Mass Spectroscopy ◽  
Amino Acid Analysis ◽  
Wheat Germ ◽  
Isolation And Identification

γ-L-Glutamyl-L-cysteine was isolated from wheat germ as the S-[2-14C]carboxymethyl derivative. Identity of the peptide was established by amino acid analysis, N-terminal procedures and mass spectroscopy.

Steric accessibility of tyrosine residues in human serum albumin

1979 ◽  
Vol 44 (5) ◽  
pp. 1657-1670 ◽  
Author(s):  
Ladislav Morávek ◽  
Mohamed Ali Saber ◽  
Bedřich Meloun
Keyword(s):  
Amino Acid ◽  
Secondary Structure ◽  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Amino Acid Analysis ◽  
Cyanogen Bromide ◽  
Tyrosine Residues ◽  
Steric Accessibility ◽  
The Individual

Human serum albumin was nitrated by an excess of tetranitromethane at pH 8.0. As shown by amino acid analysis, of the 18 tyrosine residues present in albumin about 7-7.5 residues remain unaltered, 9 residues are converted into 3-nitrotyrosine, and 1.2 residue into 3,5-dinitrotyrosine. The nitrated albumin was digested with cyanogen bromide to three fragments which comprise the whole original molecule. The individual fragments were converted into their S-sulfo derivatives and the latter digested with chymotrypsin or stepwise with trypsin and thermolysin. The yellow, nitrotyrosine-containing peptides were isolated from the digest and the positions of nitrated tyrosine residues in albumin thus located. Residues No 30, 148, 150, 161, 334, 341, 401, and 411 were identified as strongly nitrated and residues No 84, 138, 452, and 497 as medium nitrated. Residues No 140, 263, 319, 332, 353, and 367 either react weakly or were not found in nitrated form. Residue No 411 and partly also 161 were converted into 3,5-dinitrotyrosine. The accessibility of the individual tyrosine residues to the nitrating agent is discussed with respect to their positions in disulfide loops and hypothetic parts of the secondary structure of albumin.

L-Asparaginase production during static incubation of aerobically grown Escherichia coli B

1973 ◽  
Vol 19 (10) ◽  
pp. 1251-1257 ◽  
Author(s):  
L. D. Boeck ◽  
P. P. K. Ho
Keyword(s):  
Escherichia Coli ◽  
Cell Proliferation ◽  
Amino Acid ◽  
B Cells ◽  
Amino Acid Analysis ◽  
Enzyme Synthesis ◽  
E Coli ◽  
Low Levels ◽  
Escherichia Coli B ◽  
Aerobic Cell

Glucose, galactose, or pyruvate independently supported biosynthesis of 1.5–2.6 IU/ml of antilymphoma L-asparaginase during static incubation of aerobically grown E. coli B cells. Fructose, lactate, and other compounds did not produce enzyme levels in excess of 0.12 IU/ml. Asparaginase synthesis by cells incubated in the presence of either glucose or pyruvate was inhibited by fluoride, iodoacetate, and sulfite. Amino acid analysis of the modified trypticase soy broth (MTSB) medium, used for aerobic cell proliferation and subsequent enzyme synthesis during static incubation, permitted development of a chemically defined (CD) medium. Washed cells, grown aerobically in the MTSB medium, produced equivalent quantities of L-asparaginase in both the MTSB and CD media. Low levels of chloramphenicol or puromycin reduced enzyme synthesis by as much as 95%.

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.

scholarly journals Tailoring a Global Iron Regulon to a Uropathogen

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Rajdeep Banerjee ◽  
Erin Weisenhorn ◽  
Kevin J. Schwartz ◽  
Kevin S. Myers ◽  
Jeremy D. Glasner ◽  
...  
Keyword(s):  
Amino Acids ◽  
Urinary Tract ◽  
Amino Acid ◽  
Regulatory Network ◽  
Iron Homeostasis ◽  
Iron Limitation ◽  
Content Type ◽  
E Coli ◽  
General Stress ◽  
K 12

ABSTRACT Pathogenicity islands and plasmids bear genes for pathogenesis of various Escherichia coli pathotypes. Although there is a basic understanding of the contribution of these virulence factors to disease, less is known about variation in regulatory networks in determining disease phenotypes. Here, we dissected a regulatory network directed by the conserved iron homeostasis regulator, ferric uptake regulator (Fur), in uropathogenic E. coli (UPEC) strain CFT073. Comparing anaerobic genome-scale Fur DNA binding with Fur-dependent transcript expression and protein levels of the uropathogen to that of commensal E. coli K-12 strain MG1655 showed that the Fur regulon of the core genome is conserved but also includes genes within the pathogenicity/genetic islands. Unexpectedly, regulons indicative of amino acid limitation and the general stress response were also indirectly activated in the uropathogen fur mutant, suggesting that induction of the Fur regulon increases amino acid demand. Using RpoS levels as a proxy, addition of amino acids mitigated the stress. In addition, iron chelation increased RpoS to the same levels as in the fur mutant. The increased amino acid demand of the fur mutant or iron chelated cells was exacerbated by aerobic conditions, which could be partly explained by the O2-dependent synthesis of the siderophore aerobactin, encoded by an operon within a pathogenicity island. Taken together, these data suggest that in the iron-poor environment of the urinary tract, amino acid availability could play a role in the proliferation of this uropathogen, particularly if there is sufficient O2 to produce aerobactin. IMPORTANCE Host iron restriction is a common mechanism for limiting the growth of pathogens. We compared the regulatory network controlled by Fur in uropathogenic E. coli (UPEC) to that of nonpathogenic E. coli K-12 to uncover strategies that pathogenic bacteria use to overcome iron limitation. Although iron homeostasis functions were regulated by Fur in the uropathogen as expected, a surprising finding was the activation of the stringent and general stress responses in the uropathogen fur mutant, which was rescued by amino acid addition. This coordinated global response could be important in controlling growth and survival under nutrient-limiting conditions and during transitions from the nutrient-rich environment of the lower gastrointestinal (GI) tract to the more restrictive environment of the urinary tract. The coupling of the response of iron limitation to increased demand for amino acids could be a critical attribute that sets UPEC apart from other E. coli pathotypes.

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