Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: C35E7 .10
 63,145 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fixation in a traditional sense means the immersion of biological material into a chemical fluid. For permanent preservation the fixative is always "offered" (1) in excess of the cell sample, and the process of fixation is influenced by (2) chemical impurities of the fixative fluid. Both factors influence the succeeding dyeing of cells. In order to avoid these uncontrolled criteria, a new technology for controlled cell fixation has been developed, whereby freshly prepared formaldehyde and methanol gas in an "inert" gas-flow of helium was applied to thin membranes by aid of a capillary flow-in technique. The instrumental equipment consists of (1) an ultra-high vacuum flow-apparatus with a total-pressure measuring unit, (2) a gas-supply device, (3) a mass spectrometer including a pump system, and (4) a Teflon and/or glass-gas chamber for the treatment of synthetic (Hostaphan foils) or biological membranes (mesenterium) with formaldehyde as the fixative gas. The amount of "offered", adsorbed, absorbed, diffused, and desorbed fixative gas could be absolutely estimated after the saturation of the membranes with an "on-line" operating "inert" mass spectrometer of the Omegatron type. The gas treatment of the Hostaphan foils with formaldehyde showed that nearly all adsorbed gas molecules could be desorbed. In contrast to native membranes the greatest proportion of the gas molecules adhered to the biological surface, and only a small quantity were desorbable. Physisorption or physisorption and chemisorption occured depending on the adsorber surface property. A monolayer of formaldehyde of 5.10(14) to 1.10(15) molecules per 10(16) A2 surface area can be postulated on the basis of these preliminary results. This value corresponds to a mass of about 5.10(-8) g CH2O. It resulted in an area-coverage ratio of CH2O molecules per cell of 10(9):1. The membrane surface facing the gas side always amounted to 1 cm2. A fixative gas concentration of 10(6) molecules/cm3, and therefore a degree of coverage of less than 1/1000 monolayer can be estimated absolutely. For a precise determination of the degree of fixation, further experiments and the evaluation of additional physico-chemical parameters are necessary.
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PMID:A methodological study for the quantification and the control of the physico-chemical processes occurring during cell fixation. I. The development of a new technology. 35 54

An organic solvent soluble polypeptide has been isolated from photoreceptor complexes and chromatophores of Rhodospirillum rubrum. After extraction of the protein from lyophilized samples with 1:1 chloroform-methanol, it was purified by column chromatography. Its isoelectric point determined by isoelectric focusing was 7.10. When analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified polypeptide ran as a single band of an apparent molecular weight of 12 000. However, according to amino acid analysis, the minimal molecular weight based on one histidine residue per polypeptide is 19 000. The polypeptide contains no cysteine and no tyrosine. Amino acid analysis indicated that three methionines were present per histidine residue and cyanogen bromide cleavage gave four smaller peptides which were isolated by two-dimensional electrophoresis and chromatography. Spectroscopic analysis indicated the presence of three tryptophan residues per histidine and N-bromosuccinamide cleavage also gave four smaller peptides which could be isolated by two-dimensional electrophoresis and chromatography. The C-terminal amino acid was shown to be glycine by two methods, while the N-terminal amino acid appears to be blocked. The organic solvent soluble polypeptide accounts for approximately 50% of the chromatophore protein and seems to bind the antenna bacteriochlorophyll and carotenoid molecules. Using this procedure, organic solvent soluble polypeptides were isolated from several photosynthetic bacteria and were found to have substantially different amino acid contents.
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PMID:Isolation and characterization of an organic solvent soluble polypeptide component from photoreceptor complexes of Rhodospirillum rubrum. 40 30

Earlier we have shown that DNA forms stoichiometric complexes with bis-(2-guanidoethyl)-disulfide (GED), the helix being transformed from the B-like structure into the C-like one. The present work demonstrates that the DNA helix in the saturated complex does not change its conformation within a broad range of conditions: 0 less than [NaCl] less than 5.10(-2) M; 0% less than [methanol] less than 60% (v/v); 5 degrees less than temperature less than 50 degrees. Free DNA undergoes a non-cooperative winding within the B-family under all these influences. Increase in NaCl concentration beyond 5.10(-2) M results in abrupt cooperative unwinding from the C-like form to the B-like one, apparently due to GED dissociation. The obtained data are in accord with the idea that the conformational transition of DNA within the B-family is induced by change of phosphates interaction with the hydrated cations of alcaline metals; formation of strong hydrogen bonds of the phosphates with GED makes the DNA helix non-sensitive to variations of the environment.
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PMID:[Bis-(2-guanidoethyl)-disulfide, when complexed with DNA, prevents its winding within the B-family]. 46 Jan 89

The states of tyrosyl and tryptophyl residues of a dimeric protein proteinase inhibitor, Streptomyces subtilisin inhibitor (Sato, S & Murao, S. (1973), Agric. Biol. Chem. 37, 1067) were studies by solvent perturbation difference spectroscopy with methanol, ethylene glycol, polyethylene glycol, and deuterium oxide as perturbants, and by spectrophotometric titration at alkaline pH. It appeared that all three tyrosyl residues per monomer of the inhibitor were exposed on the surface of the molecule, and their apparent pK values were estimated separately to be 9.58, 11.10, and 12.42. The single tryptophyl residue per monomer of the inhibitor appeared to be partially buried in the protein molecule.
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PMID:The states of tyrosyl and tryptophyl residues in a protein proteinase inhibitor (Streptomyces subtilisin inhibitor. 59 97

The N(alpha)-arylsulfonyl-L-arginine ethyl- and propyl esters were synthesized and the kinetics of their hydrolysis by thrombin was studied. The values of kcat and Km were shown to depend on the structure of the leaving group and to decrease in the line: OCH3 greater than OC2H5 greater than OC3H7. Using methanol as an additional nucleophile, the kinetic parameters - k2, k3 and Ks - were measured for both thrombin- and trypsin-catalysed reactions. A similarity of two enzymes at the stage of Michaelis complex formation was revealed: the Ks values for both enzymes were practically identical (18.10(-5)M). The differences between thrombin and trypsin were observed at the stages of chemical conversion of substrates and were especially well-pronounced at the stage of acylation. It was shown that the k2 values for thrombin were lower than that for trypsin and the k2/k3 ratio of TAME hydrolysis by trypsin was equal to 21, while that for thrombin was 4.5. This finding is indicative of an essential role of the acylation step in thrombin-catalysed hydrolysis of the esters under study.
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PMID:[Determination of the kinetic parameters of individual stages of M(alpha)-arylsulfonyl-L-arginine ester hydrolysis by thrombin and trypsin]. 65 99

A gas-liquid chromatographic method has been developed for the analysis of residues of chlorphoxim, 2-chloro-alpha ((diethoxyphosphinothioyl)oxy)imino)-benzeneacetonitrile, in water and fish. The method is based on the in-block methylation of chlorphoxim with 0.01M trimethylanilinium hydroxide in methanol. The derivative, O,O-diethyl O-methyl phosphorothioate, was determined quantitatively by using a flame photometric detector specific for phosphorus. The in-block reaction is 70% efficient. Water samples were extracted with hexane; fish were extracted with methylene chloride and cleaned up on an acetonitrile-hexane partition column. Recoveries from water and fish samples spiked with chlorphoxim averaged 86.3 and 80.4%, respectively. Limits of detection were 10.0 ppb for 5 g samples of fish and 0.10 ppb for 300 ml water samples.
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PMID:Gas-liquid chromatographic determination of chlorphoxim residues in water and fish by in-block methylation. 96 32

The determination of diacetyl, 2,3-pentanedione and acetoin was performed in two steps. Diacetyl and 2.3-pentanedione were driven off with gaseous nitrogen at 60 degrees C and collected in ice cooled methanol. The quantitative gaschromatographical determination follows after directly injecting this solution into the gas chromatograph employing an electron capture detector which indicates selectively the vicinale diketones. In a second experiment acetoin was determined by a differential method after oxidizing acetoin to diacetyl. The investigation of 57 German white wines of various vintages, varieties and quality classes yielded the following results: Diacetyl: Limits of variability (V) = 0.08-3.40 mg/l, average amount (M) = 0.42 mg/l; 2.3-pentanedione: V = 0.02-0.36 mg/l, M = 0.10 mg/l; Acetoin: V = 1.9-31.7 mg/l, M = 5.9 mg/l. No differences could be observed with regard to the various quality classes. In 20 red vines of various European origines the following amounts were observed: Diacetyl: V = 0.26-4.06 mg/l, M = 1.46 mg/l; 2.3-pentanedione: V = 0.08-0.88 mg/l, M = 0.25 mg/l; Acetoin: V = 5.9-38.2 mg/l, M = 15.0 mg/l. For a rule the red wines show considerable higher contents of diacetyl, 2.3-pentanedione and acetoin than the white wines.
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PMID:[Gaschromatographical determination of diacetyl, acetoin, and 2,3-pentanedione in wine (author's transl)]. 97 47

Mouse bone marrow cells were cultured to determine some basic characteristics of the diffusion chamber (DC) technique. The main findings were as follows: (i) Incorporated 3H-thymidine was conveniently measured after deposition of a cell sample on glass fibre discs followed by methanol washing. Varying the specific activity from approximately 2-approximately 20 Ci/mmole did not affect the relationship between DC cellularity and isotope incorporation. Isotope uptake was similar regardless of whether 3H-thymidine of high or low specific activity had been used. (ii) Higher cell yields were obtained when Millipore or Acropor filters were heat-sealed rather than glued to the plastic rings, when Millipore filters were moistened before DC filling, when we omitted gluing the closing plugs, and when we used an average pore size of 0.22 mum for the DC walls rather than one of 0.10 mum or 0.45 mum. Varying the ring thickness from 2.0-2.5 mm did not impair the cell growth, nor did removal of a softening agent from the plastic rings improve it. (iii) More cells were retrieved from DC carried by young rather than by older mice. Results were not influenced by sex or strain differences between the donor and the host or by the number of implants, whether single or double, within an individual host. (iv) Adding Ficoll to the pronase solution increased the yield of viable CFU-C. (V) Diffusion rate through the DC walls declined with increasing period of culturing, so that i.p. 3H-thymidine is not a flash label for 7-day cultures, for example. The great variability of 3H-thymidine diffusion into i.p. DC was markedly reduced by in vitro exposure to the unopened DC to the isotope. (vi) DC could be incubated in vitro in a medium devoid of protein for at least 6 hours without a fall in 3H-thymidine incorporation rate or CFU-C content, provided that pH was kept constant.
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PMID:Diffusion chamber culturing of haematopoietic cells: methodological investigations and improvement of the technique. 110 Apr 20

Fluorescamine was subjected to reaction with dopamine and norepinephrine (catecholamines) and with 3-methoxytyramine and normetanephrine (3-methyl metabolites of catecholamines) in phosphate or borate buffer. Catecholamines gave the highest fluorescent intensity at pH 8.0 in phosphate buffer but lower fluorescence in borate buffer. The fluorophores produced in phosphate or borate buffer were the same but the fluorescence intensities were suppressed in borate buffer. The dopamine and norepinephrine fluorophores were separated by high-pressure liquid chromatography on Hitachi 3011 gel with methanol-0.10 M Tris buffer of pH 8.0 (7:3). They were measurable at the 100-pmole level. The metabolites were also measurable by the same chromatography. By using methanol-0.15 M borate buffer of pH 8.0, cate-chol-O-methyltransferase activity might be assayed.
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PMID:Fluorimetric assay of dopamine, norepinephrine and their 3-O-methyl metabolites by using fluorescamine. 114

After preoperative skin disinfection in pediatric surgery, serum levels of isopropanol up to 12.2 mg/l (MW 5.0 mg/l +/- 3.37, n = 26) were found. They result from a rapid and prolonged but uncharacteristic percutaneous resorption of the isopropanol-containing disinfectant. In about 50% of the cases, serum levels of acetone showed an increase up to 82 mg/l already before skin disinfection, presumably caused by preoperative starvation. After skin disinfection, raised acetone levels were found in 19 of 26 cases. As increased isopropanol and acetone levels are discussed as alcoholism markers, a falsification of congener analysis after skin disinfection, e.g. in cases of adult victims of accidents, has to be taken into consideration. Endogenous serum levels of methanol (0.87 mg/l +/- 0.49), ethanol (0.32 mg/l +/- 0.09), acetaldehyde (0.31 mg/l +/- 0.10) and others remained unaffected. Some uncharacteristic elevations of propanol-1 levels are caused by contaminated rubber caps.
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PMID:[Isopropanol and acetone level in serum after preoperative surface disinfection with antiseptics containing isopropanol]. 138 18


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