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At least 541 records · Page 30Linked to original sources
PubMed1975

The hormonal control of activity of skeletal muscle phosphorylase kinase. Amino-acid sequences at the two sites of action of adenosine-3':5'-monophosphate-dependent protein kinase.

Two tryptic phosphopeptides containing the sites on the alpha and beta subunits of phosphorylase kinase which are phosphorylated by protein kinase, dependent on adenosine 3':5'-monophosphate (cyclic AMP), have been isolated and their amino acid sequences have been determined. 32P-labelled phosphorylase kinase, containing 1.9 mol phosphate per mol enzyme, was digested with an equimolar quantity of trypsin for 2.5 min at pH 7.0, 20 degrees C. This treatment released nearly all the 32P radioactivity associated with the beta subunit as trichloroacetic-acid-soluble material. Only a small proportion of the 32P radioactivity associated with the alpha subunit was solubilised, the remainder being removed in the trichloroacetic acid pellet. The beta-subunit tryptic phosphopeptide was completely resolved from traces of the alpha-subunit phosphopeptide by gel filtration on Sephadex G-25. Further purification by peptide mapping separated the phosphopeptide into four components, each derived from the same nine-amino-acid segment of the betachain, which was found to possess the sequence: Gln-Ser-Gly-Ser(P)-Val-Ile-Tyr-Pro-Leu-Lys. The four components were produced by the partial cyclisation of the N-terminal glutaminyl residue, and by the presence of two alleles for the beta subunit in the rabbit population, which led to a valine-isoleucine ambiguity. The alpha-subunit phosphopeptide was liberated from the trichloroacetic acid pellet by redigestion with trypsin. It was the largest component in the digest which remained soluble in 5% trichloroacetic acid, and obtained in a highly purified form by a single filtration on Sephadex G-50. The peptide comprised 39 amino acids of which nine were serine and three were threonine residues. Only one residue, the serine at position three from the amino terminus, was phosphorylated. The amino-terminal sequence of the peptide was shown to be: Arg-Leu-Ser(P)-Ile-Ser-Thr-Glu-Ser-Glx-Pro-Asx-Gly. The sequences confirm the stoichiometry of the reaction and the absolute specificity of cyclic-AMP-dependent protein kinase for just two of the 200 serine residues in the enzyme. These results and an inspection of the rate of phosphorylation of a number of skeletal muscle proteins, including each enzyme of the glycolytic pathway, lead to the conclusion that cyclic-AMP-dependent protein kinase is an extremely specific enzyme. The molecular basis of this specificity is discussed.

Adenosine Triphosphate↗
PubMedDate not supplied

Uncovering the unfoldome: enriching cell extracts for unstructured proteins by acid treatment.

A method to enrich cell extracts in totally unfolded proteins was investigated. A literature search revealed that 14 of 29 proteins isolated by their failure to precipitate during perchloric acid (PCA) or trichloroacetic acid (TCA) treatment where also shown experimentally to be totally disordered. A near 100 000-fold reduction in yield was observed after 5% or 9% PCA treatment of total soluble E. coli protein. Despite this huge reduction, 158 and 142 spots were observed from the 5% and the 9% treated samples, respectively, on silver-stained 2-D SDS-PAGE gels loaded with 10 microg of protein. Treatment with 1% PCA was less selective with more visible spots and a greater than 3-fold higher yield. A substantial yield of unprecipitated protein was obtained after 3% TCA treatment, suggesting that the common use of TCA precipitation prior to 2-D gel analysis may result in loss of unstructured protein due to their failure to precipitate. Our preliminary analysis suggests that treating total protein extracts with 3-5% PCA and determining the identities of soluble proteins could be the starting point for uncovering unfoldomes (the complement of unstructured proteins in a given proteome). The 100 000-fold reduction in yield and concomitant reduction in number of proteins achieved by 5% PCA treatment produced a fraction suitable for analysis in its entirety using standard proteomic techniques. In this way, large numbers of totally unstructured proteins could be identified with minimal effort.

Bacterial Proteins↗
PubMed1986

Assessment of binding of L-cystine and L-lysine by rat renal brush-border membranes.

Cystine and lysine bind to isolated rat renal brush-border vesicles. Three methods to determine the extent of amino acid binding to the membranes have been compared, one relying on the osmotic reactivity of the vesicle, a second by trichloroacetic acid precipitation of membrane-bound material and a third by initial rate analysis. For cystine, all methods yield comparable results at early time points, indicating the trichloroacetic acid method is a simple and valuable tool for binding estimation under initial-rate or near initial-rate conditions. For lysine, initial rate analysis and osmotic perturbation are the methods of choice since lysine co-precipitates with trichloroacetic acid.

Animals↗
PubMed1986

[Trichloroethylene metabolism in chronic liver disorders induced by carbon tetrachloride].

Numerous reports have been published in the field of industrial health on biological monitoring of trichloroethylene exposure, but these studies have been confined to healthy humans. Trichloroethylene metabolism in individuals with chronic liver diseases has not been clarified. This experiment was therefore performed on rats that were administrated carbon tetrachloride subcutaneously for three months to induce chronic liver damage. The metabolism of trichloroethylene and its metabolites, chloral hydrate and trichloroethanol, were investigated using the isolated liver perfusion method. Comparing the changes of these substances in the chronically damaged liver with those in the intact liver, the following results were observed in the chronically damaged liver: The conversion of trichloroethylene to trichloroethanol and trichloroacetic acid decreased. The reduction of chloral hydrate to trichloroethanol increased. The oxidation of chloral hydrate to trichloroacetic acid decreased. The biliary excretion of trichloroethanol and trichloroacetic acid decreased.

Animals↗
PubMed1984

Factors influencing peroxisome proliferation in cultured rat hepatocytes.

A primary rat hepatocyte culture system has been developed for the study of peroxisome proliferation. Maximal induction of peroxisomal activity requires supplementation of the culture medium with hydrocortisone. The addition of clofibric acid (0.01-1 mM), mono-(2-ethylhexyl)phthalate (0.01-0.5 mM) and trichloroacetic acid (0.1-5 mM) to cultured rat hepatocytes resulted in a time- and dose-related increase in CN- insensitive palmitoyl CoA oxidation (maximal increases: 27-, 15.5-, and 5-fold respectively) and mitochondrial alpha-glycerophosphate dehydrogenase activity (maximal increases: 7.3-, 5.8-, and 1.6-fold respectively). Electron microscopic examination revealed smooth endoplasmic reticulum proliferation and morphometric analysis indicated an increase in fractional peroxisomal volume of X 8 and X 4 for clofibric acid (1 mM) and trichloroacetic acid (2.5 mM), respectively. SDS-PAGE of cell homogenates revealed an intensified protein band of mol. wt. 76-78,000. The induction of peroxisomal beta-oxidation by clofibric acid was elevated from 9- to 12-fold by supplementation of the medium with L-carnitine (2 mM).

Animals↗
PubMed1976

[Metabolism of tetrachloroethylene in guinea pigs (author's transl)].

Tetrachloroethylene oxide was chemically prepared from tetrachloroethylene, and the metabolites of the oxide in guinea pigs were analyzed by gaschromatography and Fujiwara reaction. The results obtained are as follows: 1) Trichloroacetic acid appeared in gaschromatogram after injection of tetrachloroethylene oxide, but trichloroethanol did not. 2) The metabolites analyzed by Fujiwara reaction after injection of tetrachloroethylene oxide were composed of large proportion of trichloroacetic acid and small proportion of trichloroethanol. 3) The ratio of trichloroacetic acid to trichloroethanol in the urine in case of tetrachloroethylene oxide was relatively similar to that of tetrachloroethylene. 4) The effects of pH (2.0 and 10.0) and temperature (4 degrees C and 37 degrees C) on the urinary metabolites suggest that the substance equivalent to trichloroethanol by Fujiwara reaction in metabolites may not be a real one. 5) Toxicity of tetrachloroethylene oxide seems to be much higher as compared with that of tetrachloroethylene in consideration of the maximum allowable dose in guinea pigs. 6) It is supposed from our experiments that tetrachloroethylene oxide is an intermediary metabolite of tetrachloroethylene.

Animals↗
PubMed1963

INFLUENCE OF GROWTH MEDIUM ON ASSIMILATORY ACTIVITIES OF ESCHERICHIA COLI.

Clifton, C. E. (Stanford University, Stanford, Calif.). Influence of growth medium on assimilatory activities of Escherichia coli. J. Bacteriol. 85:1371-1377. 1963.-Nutrient agargrown cells assimilate about 50% of the glucose added to washed suspensions (phosphate buffer, pH 7.2, 30 C), as indicated by O(2) consumption or C(14)-uptake from uniformly labeled glucose. Most of the nonassimilated glucose is oxidized, but a small portion remains in forms other than glucose in the suspension medium. Cells from glucose agar, however, assimilate only about 20 to 30% of the U-glucose and ferment a considerable portion of the remainder, the extent of each being determined in part at least by growth conditions. Evidence is presented that this behavior is the result of metabolic controls induced during growth. C(14) from U-glucose appeared in all fractions of either agar- or glucose agar-grown cells, the highest percentage being present in cellular matter insoluble in hot 5% trichloroacetic acid. Data on the distribution of C(14) from 1-, 2-, and 6-glucose, and from acetate and pyruvate, are also presented.

Acetates↗
PubMed1978

Structural arrangement of polymers within the wall of Streptococcus faecalis.

The structure of the cell wall of Streptococcus faecalis was studied in thin sections and freeze fractures of whole cells and partially purified wall fractions. Also, the structures of wall preparations treated with hot trichloroacetic acid to remove non-peptidoglycan wall polymers were compared with wall preparations that possess a full complement of accessory polymers. The appearance of the wall varied with the degree of hydration of preparations and physical removal of the cell membrane from the wall before study. Seen in freeze fractures of whole cells, the fully hydrated wall seemed to be a thick, largely amorphic layer. Breaking cells with beads caused the cell membrane to separate from the wall and transformed the wall from a predominantly amorphic layer to a structure seemingly made up of two rows of "cobblestones" enclosing a central channel of lower density. Dehydration of walls seemingly caused the cobblestones to be transformed into two bands which continued to be separated by a channel. This channel was also observed in isolated wall preparations treated with hot trichloroacetic acid to remove non-peptidoglycan polymers. These observations are consistent with the interpretation that both peptidogylcan and non-peptidoglycan polymers are concentrated at the outer and inner surfaces of cell walls. These observations are discussed in relation to possible models of wall structure and assembly.

Cell Wall↗
PubMed2005

Photocatalytic hydrogen generation in the presence of chloroacetic acids over Pt/TiO2.

In the presence of chloroacetic acids, the photocatalytic hydrogen evolution and decomposition of the pollutants over Pt/TiO2 have been investigated. The Pt/TiO2 was prepared by photodeposition. Monochloroacetic acid and dichloroacetic acid enhance photocatalytic hydrogen generation, whereas trichloroacetic acid does not. The photocatalytic oxidation of monochloroacetic acid and dichloroacetic acid mainly produces CO2, HCl and formaldehyde, whereas the photocatalytic oxidation of trichloroacetic acid mainly produces CO2 and HCl. The effect of the concentration of monochloroacetic acid and dichloroacetic acid on the hydrogen generation rate is consistent with a Langmuir-Hinshelwood kinetic model. A possible reaction mechanism was discussed.

Acetates↗
PubMed1974

Antigens of Streptococcus mutans. II. Characterization of an antigen resembling a glycerol teichoic acid in walls of strain BHT.

Cold 10% trichloroacetic acid was used to extract antigens from purified cell walls of Streptococcus mutans BHT. Column chromatography on Biogel P-100 resolved two serologically reactive fractions (B and C). These fractions were ascertained to be relatively pure by recycling on Biogel P-100, Ouchterlony double-diffusion analysis, and immunoelectrophoresis. Fractions B and C demonstrated bands of absolute homology by double-diffusion but different mobilities by immunoelectrophoresis. Chemical analysis indicated that fraction B is a polysaccharide composed principally of rhamnose and galactose, with smaller amounts of glucose and glucosamine. Small quantities of glycerol and phosphorus also were found. Fraction C was composed mainly of galactose, glycerol, and phosphorus. Alkaline hydrolysis of this fraction yielded products typically released by the degradation of a glycerol teichoic acid, such as glycerol monophosphate, glycerol diphosphate, inorganic phosphorus, and several glycosyl glycerol phosphates. Diglycerol triphosphate was not detected. Side-group analysis revealed that glycerol was substituted by mono- and trigalactosyl moieties. Fraction C was deduced to contain 25 glycerol phosphate units per polymer length. Hapten inhibition studies revealed a beta-galactoside as the probable hapten on this antigen. The BHT teichoic acid reacted strongly with FA-1 antiserum. It showed bands of homology with both BHT and FA-1 crude acid extracts upon double-diffusion, using antisera to either strain. The BHT teichoic acid also displayed immunoelectrophoretic behavior identical to one of the mobile FA-1 cell wall antigens, again using either serum to develop precipitin bands. It is concluded this antigen may possess a serotype-specific determinant for S. mutans serotype b.

Acrylamides↗
PubMed1990

Demethylation pathways in caffeine metabolism as indicators of variability in 1,1,1-trichloroethane oxidation in man.

Twenty volunteers were exposed to 191 +/- 7 p.p.m. 1,1,1-trichloroethane or 50 +/- 2 p.p.m. perchloroethylene vapour for 6 hr. They were then evaluated for their rate of caffeine metabolism, mephenytoin hydroxylation and debrisoquine hydroxylation. Seven subjects were identified as 'fast acetylators' of caffeine and one person as a slow metabolizer of debrisoquine. The "slow acetylators" exposed to perchloroethylene excreted an average of 3.83 +/- 0.35 mg trichloroacetic acid within 24 hr (N = 13, +/- S.E.) and the 'fast acetylators' 3.58 +/- 0.48 mg (N = 7, +/- S.E.). The excretion of trichloroethanol by the same persons after 1,1,1-trichloroethane exposure was 14.1 +/- 1.12 mg and 16.7 +/- 1.48 mg, respectively. The excretion of trichloroacetic acid in the latter exposure varied significantly between the seven 'fast' and 13 'slow acetylators' (0.43 +/- 0.08 mg versus 1.03 +/- 0.19 mg; +/- S.E.; P = 0.037). A multiple linear regression analysis confirmed this association when other factors, such as body weight, creatinine clearance, smoking habit and alcohol consumption, were taken into account. One volunteer proved to be a poor hydroxylator of debrisoquine and excreted half the amount of trichloroacetic acid in the perchloroethylene exposure and half the amount of trichloroethanol in the 1,1,1-trichloroethane exposure compared to the others. A reduction in the solvent metabolism could thus be predicted by the debrisoquine test. On the other hand, the caffeine test predicted faster oxidation of trichloroethanol which could be of toxicological and pharmacological importance e.g. in the clinical use of chloral.

Adult↗
PubMed1997

Characterization of a partially structured state in an all-beta-sheet protein.

Cardiotoxin analogue III (CTX III) is a low-molecular-mass all-beta-sheet protein isolated from the Taiwan cobra (Naja naja atra) venom. A stable partially structured state similar to the "molten globule' state has been identified for CTX III in a 3% (w/v) solution of 2,2,2-trichloroacetic acid at 298 K. This stable state has been structurally characterized using a variety of techniques such as CD, 1-anilinonaphthalene-8-sulphonate fluorescence binding, Fourier transform IR and two-dimensional NMR spectroscopy techniques. Direct assignment of the homonuclear two-dimensional NMR spectra of the protein in 3% trichloroacetic acid showed that drastic structural perturbation had not taken place in the protein and that the 'intermediate' state retained a significant portion of the native secondary-structural interactions. It is found that about 65% of the native beta-sheet structural contacts are maintained in the partially structured state of CTX III in 3% trichloroacetic acid.

Circular Dichroism↗
PubMed1999

Report of phenol peel for Asians.

With the advancement of trichloroacetic acid peel technology and wound care, trichloroacetic acid peeling has become very successful in Korea. Its success has opened studies on the possibility of using phenol on Korean skin. Dr. Mee's phenol formula (molding mask technique) was chosen for experiments on Korean skin because of the presumed safety of use on non-Caucasian skin. Between January of 1996 and January of 1998, 30 cases of significant small pox scars were treated with phenol at the Korea University Anam Hospital. The age range was from 43 to 60 years, with a mean of 49 years. The average follow-up period was 13 months, ranging from 1 month to 2 years. All of the procedures were performed in the operating room while the patient was under deep i.v. sedation. After the entire face was peeled, it was covered with an occlusive tape mask. During the recovery period, the patients underwent a post-peel skin care program. All 30 patients showed significant improvement of the severe pox marks with a marked rejuvenation effect. There was no sign of hypopigmentation or hyperpigmentation. As a complication, two patients developed hypertrophic scars on the perioral area, which responded well to steroid injections. Another pair of patients had herpetic infection, which left minimal scarring. Five patients developed cardiac arrhythmia with this rapid technique, but this was safely managed by an anesthesiologist during the procedure. Korean skin belongs to Fitzpatrick types IV and V and occasionally to type III or VI. It is common knowledge that performing chemical peeling on the latter types of skin is dangerous, but in this report, excellent results were obtained from all 30 patients, even though the peeling itself was very deep. With more knowledge and experience, phenol peel can be safely conducted on Asian skin.

Adult↗
PubMed1975

Determinations of nonprotein nitrogen content of cheese whey.

Nonprotein nitrogen in pooled sweet (Cheddar and Dagano) and acid (cottage) wheys was estimated by currently proposed dialysis and chemical precipitation methods. Kjeldahl nitrogen analyses of (a) membrane retentates after water dialysis, and (b) 12% trichloroacetic acid plus .2% phosphotungstic acid filtrates indicated that nonprotein nitrogen values vary significantly with the method of sample preparation. Membrane porosity influence nonprotein nitrogen values for molecular weight cut-offs of 3500, 6000 to 8000 and 12,000 to 14,000. Dialyzable nitrogen values with all membranes were lower than 12% trichloroacetic acid soluble nitrogen for both wheys and higher than the 12% trichloroacetic acid + .2% phosphotungstic acid soluble nitrogen for all but the 3500 molecular weight cut-off membrane. The dialyzable nonprotein nitrogen fraction was heterogeneous but more that 80% was less than 3500 in molecular weight.

Animals↗