scholarly journals Isolation and characterization of six human hepatic isometallothioneins

1985 ◽  
Vol 231 (2) ◽  
pp. 375-382 ◽  
Author(s):  
P E Hunziker ◽  
J H R Kägi
Keyword(s):  
Amino Acids ◽  
Aromatic Amino Acids ◽  
Reversed Phase ◽  
Low Ph ◽  
Autopsy Material ◽  
Isolation And Characterization ◽  
Cysteine Content ◽  
Hepatic Metallothionein ◽  
Mammalian Metallothioneins

Human hepatic metallothionein (MT) was separated into six isoforms by using reversed-phase h.p.l.c. at the analytical and preparative levels. By comparison with the h.p.l.c. elution profiles of the charge-separable species MT-1 and MT-2 isolated by the procedure of Bühler & Kägi [(1974) FEBS Lett. 39, 229-234], five of these isoproteins are identified as hitherto unresolved subforms of MT-1, and one is identical with MT-2. The six isoforms have distinct and reproducible retention times at neutral pH, where the metal remains bound to the protein, and at low pH, where the metal is removed. Their amino acid compositions display the high cysteine content and the lack of aromatic amino acids and of histidine typical of mammalian metallothioneins, but they differ significantly with respect to all other amino acids. A survey of autopsy material indicates that in adult human liver all six isoforms are usually expressed, albeit in somewhat variable relative proportions.

Characterization of an isozyme of S-adenosylmethionine synthetase from rat liver

1984 ◽  
Vol 62 (5) ◽  
pp. 276-279 ◽  
Author(s):  
C. H. Lin ◽  
W. Chung ◽  
K. P. Strickland ◽  
A. J. Hudson
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Amino Acid ◽  
Enzymatic Synthesis ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Aromatic Amino Acids ◽  
Adenosylmethionine Synthetase ◽  
Cellulose Column

An isozyme of S-adenosylmethionine synthetase has been purified to homogeneity by ammonium sulfate fractionation, DEAE-cellulose column chromatography, and gel filtration on a Sephadex G-200 column. The purified enzyme is very unstable and has a molecular weight of 120 000 consisting of two identical subunits. Amino acid analysis on the purified enzyme showed glycine, glutamate, and aspartate to be the most abundant and the aromatic amino acids to be the least abundant. It possesses tripolyphosphatase activity which can be stimulated five to six times by S-adenosylmethionine (20–40 μM). The findings support the conclusion that an enzyme-bound tripolyphosphate is an obligatory intermediate in the enzymatic synthesis of S-adenosylmethionine from ATP and methionine.

Characterization of transient species in laser photolysis of aromatic amino acids using acetone as photosensitizer

1999 ◽  
Vol 42 (6) ◽  
pp. 561-566 ◽  
Author(s):  
Qinhua Song ◽  
Yeping Xu ◽  
Shuqin Yu ◽  
Congxiang Chen ◽  
Xingxiao Ma ◽  
...  
Keyword(s):  
Amino Acids ◽  
Aromatic Amino Acids ◽  
Laser Photolysis ◽  
Transient Species

scholarly journals Identification of the Tyrosine- and Phenylalanine-Derived Soluble Metabolomes of Sorghum

2021 ◽  
Vol 12 ◽  
Author(s):  
Jeffrey P. Simpson ◽  
Jacob Olson ◽  
Brian Dilkes ◽  
Clint Chapple
Keyword(s):  
Amino Acids ◽  
Cinnamic Acid ◽  
Aromatic Amino Acids ◽  
Flavonoid Glycosides ◽  
Coumaric Acid ◽  
Biotic And Abiotic Stress ◽  
Proportional Contribution ◽  
Negative Ionization ◽  
Derivatives Of

The synthesis of small organic molecules, known as specialized or secondary metabolites, is one mechanism by which plants resist and tolerate biotic and abiotic stress. Many specialized metabolites are derived from the aromatic amino acids phenylalanine (Phe) and tyrosine (Tyr). In addition, the improved characterization of compounds derived from these amino acids could inform strategies for developing crops with greater resilience and improved traits for the biorefinery. Sorghum and other grasses possess phenylalanine ammonia-lyase (PAL) enzymes that generate cinnamic acid from Phe and bifunctional phenylalanine/tyrosine ammonia-lyase (PTAL) enzymes that generate cinnamic acid and p-coumaric acid from Phe and Tyr, respectively. Cinnamic acid can, in turn, be converted into p-coumaric acid by cinnamate 4-hydroxylase. Thus, Phe and Tyr are both precursors of common downstream products. Not all derivatives of Phe and Tyr are shared, however, and each can act as a precursor for unique metabolites. In this study, 13C isotopic-labeled precursors and the recently developed Precursor of Origin Determination in Untargeted Metabolomics (PODIUM) mass spectrometry (MS) analytical pipeline were used to identify over 600 MS features derived from Phe and Tyr in sorghum. These features comprised 20% of the MS signal collected by reverse-phase chromatography and detected through negative-ionization. Ninety percent of the labeled mass features were derived from both Phe and Tyr, although the proportional contribution of each precursor varied. In addition, the relative incorporation of Phe and Tyr varied between metabolites and tissues, suggesting the existence of multiple pools of p-coumaric acid that are fed by the two amino acids. Furthermore, Phe incorporation was greater for many known hydroxycinnamate esters and flavonoid glycosides. In contrast, mass features derived exclusively from Tyr were the most abundant in every tissue. The Phe- and Tyr-derived metabolite library was also utilized to retrospectively annotate soluble MS features in two brown midrib mutants (bmr6 and bmr12) identifying several MS features that change significantly in each mutant.

scholarly journals Isolation, Identification and Characterization of Degradation Impurity of Atorvastatin in Fixed Dose Combination of Atorvastatin and Ezetimibe

2019 ◽  
Vol 11 (05) ◽  
Author(s):  
Rajesh Desai ◽  
Suresh Koradia
Keyword(s):  
Reversed Phase ◽  
Fixed Dose Combination ◽  
Fixed Dose ◽  
Forced Degradation ◽  
Preparative Hplc ◽  
Atorvastatin Calcium ◽  
Isolation And Characterization ◽  
Dose Combination ◽  
Liquid Chromatographic

The objective of this study is to isolation and characterization of unknown degradation product of Atorvastatin calcium in combination formulation product with Ezetimibe by using modern techniques of separation and aracterization. An unknown impurity is generating during a forced degradation study of Atorvastatin and Ezetimibe fixed-dose combination tablets. By using the gradient reversed-phase high-pressure liquid chromatographic method, unknown degradation impurity was detected and quantified in the range of 0.05% to 0.2% of Atorvastatin. The impurity was enriched by extreme oxidation degradation of Atorvastatin and isolated through preparative HPLC. The structure of the impurity was characterized by mass and NMR spectrum.

Biochemical and functional characterization of Mycobacterium tuberculosis ketol-acid reductoisomerase

Microbiology ◽  
2021 ◽  
Vol 167 (9) ◽  
Author(s):  
Nirbhay Singh ◽  
Anu Chauhan ◽  
Ram Kumar ◽  
Sudheer Kumar Singh
Keyword(s):  
Amino Acids ◽  
Mycobacterium Tuberculosis ◽  
Type Species ◽  
Low Ph ◽  
Stress Conditions ◽  
Starvation Stress ◽  
Content Type ◽  
E Coli ◽  
Link Type

Branched-chain amino acids (BCAAs) are essential amino acids, but their biosynthetic pathway is absent in mammals. Ketol-acid reductoisomerase (IlvC) is a BCAA biosynthetic enzyme that is coded by Rv3001c in Mycobacterium tuberculosis H37Rv (Mtb-Rv) and MRA_3031 in M. tuberculosis H37Ra (Mtb-Ra). IlvCs are essential in Mtb-Rv as well as in Escherichia coli . Compared to wild-type and IlvC-complemented Mtb-Ra strains, IlvC knockdown strain showed reduced survival at low pH and under low pH+starvation stress conditions. Further, increased expression of IlvC was observed under low pH and starvation stress conditions. Confirmation of a role for IlvC in pH and starvation stress was achieved by developing E. coli BL21(DE3) IlvC knockout, which was defective for growth in M9 minimal medium, but growth could be rescued by isoleucine and valine supplementation. Growth was also restored by complementing with over-expressing constructs of Mtb-Ra and E. coli IlvCs. The E. coli knockout also had a survival deficit at pH=5.5 and 4.5 and was more susceptible to killing at pH=3.0. The biochemical characterization of Mtb-Ra and E. coli IlvCs confirmed that both have NADPH-dependent activity. In conclusion, this study demonstrates the functional complementation of E. coli IlvC by Mtb-Ra IlvC and also suggests that IlvC has a role in tolerance to low pH and starvation stress.

scholarly journals Isolation and Characterization of Mutations in theEscherichia coli Regulatory Protein XapR

1999 ◽  
Vol 181 (14) ◽  
pp. 4397-4403 ◽  
Author(s):  
Casper Jørgensen ◽  
Gert Dandanell
Keyword(s):  
Amino Acids ◽  
Purine Nucleoside Phosphorylase ◽  
Mutational Analysis ◽  
Regulatory Protein ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Wild Type ◽  
Isolation And Characterization ◽  
In The Wild

ABSTRACT In this work, the LysR-type protein XapR has been subjected to a mutational analysis. XapR regulates the expression of xanthosine phosphorylase (XapA), a purine nucleoside phosphorylase inEscherichia coli. In the wild type, full expression of XapA requires both a functional XapR protein and the inducer xanthosine. Here we show that deoxyinosine can also function as an inducer in the wild type, although not to the same extent as xanthosine. We have isolated and characterized in detail the mutants that can be induced by other nucleosides as well as xanthosine. Sequencing of the mutants has revealed that two regions in XapR are important for correct interactions between the inducer and XapR. One region is defined by amino acids 104 and 132, and the other region, containing most of the isolated mutations, is found between amino acids 203 and 210. These regions, when modelled into the three-dimensional structure of CysB from Klebsiella aerogenes, are placed close together and are most probably directly involved in binding the inducer xanthosine.

ISOLATION AND CHARACTERIZATION OF RIBONUCLEIC ACID FROM RAT LENS

1962 ◽  
Vol 40 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Anima Devi
Keyword(s):  
Amino Acids ◽  
The Other ◽  
Ocular Lens ◽  
E Coli ◽  
Isolation And Characterization ◽  
Coiled Structure ◽  
Calf Thymus ◽  
Original Procedure ◽  
Polynucleotide Chain

RNA from rat ocular lens has been isolated by a method based on Kirby's original procedure (7), but greatly modified so as to avoid any degradation of RNA by RNase during the process of its extraction from lenses. The absorption at 260 mμ of a 1.0% solution of this purified material in a 1-cm cell is 1.95. Its N/P ratio is 1.58. It has 20 to 25% activity of that of yeast-soluble RNA in accepting activated amino acids. When this RNA (like all other RNA's) is heated and cooled the polynucleotide chain can again form loops, thus suggesting a randomly coiled structure for this RNA. On the other hand, DNA preparations from calf thymus, rat liver, and E. coli showed irreversible changes when heated and cooled.

PARTIAL CHARACTERIZATION OF SOIL HUMIC ACIDS THROUGH BIODEGRADATION

1967 ◽  
Vol 13 (5) ◽  
pp. 581-586 ◽  
Author(s):  
S. P. Mathur ◽  
E. A. Paul
Keyword(s):  
Amino Acids ◽  
Oxygen Tension ◽  
Humic Acids ◽  
Aromatic Amino Acids ◽  
Partial Characterization ◽  
Penicillium Frequentans ◽  
Enzyme Systems ◽  
Culture Filtrates ◽  
Partial Degradation

A strain of Penicillium frequentans was successfully employed for partial degradation and characterization of humic acids. Salicyl alcohol and salicylaldehyde were detected in culture filtrates of the fungus utilizing humates under reduced oxygen tension. The enzyme systems involved in the degradation of humic acids were adaptive. The humate-adapted mycelium was capable of metabolizing a number of compounds which occur in soil as products of degradation of lignin, aromatic amino acids, and plant glycosides but not polyphenolic hydrocarbons, resorcinol, and phloroglucinol.

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