scholarly journals The influence of some methodological factors on measurement of tryptophan oxygenase activities in crude homogenates of rat liver

1983 ◽  
Vol 209 (3) ◽  
pp. 831-836 ◽  
Author(s):  
L Stowell ◽  
J Mørland
Keyword(s):  
Rat Liver ◽  
Liver Tissue ◽  
Post Mortem ◽  
Temperature Dependent ◽  
Tryptophan Oxygenase ◽  
Oxygenase Activity ◽  
Liver Homogenates ◽  
Independent Reaction

1. With two different methods for assaying the tryptophan oxygenase activity in rat liver homogenates, the effects of some methodological factors on the activity of the enzyme were studied. 2. In fed, but not in starved, rats a compound(s) absorbing at 365 nm, interfering with the reading of kynurenine absorbance, disappeared gradually during incubation. 3. A correction for this tryptophan-independent reaction was necessary in order to determine correct tryptophan oxygenase activity. 4. Blood remaining in liver tissue post mortem can serve as a source of cofactor haem for tryptophan oxygenase, causing spuriously high values for the activity of the holoenzyme form of tryptophan oxygenase. 5. A rapid and progressive activation of tryptophan oxygenase post mortem occurs in undisrupted liver tissue, and this activation is temperature-dependent.

VANILLINSÄURE ALS ENDPRODUKT DES ABBAUES VON ADRENALIN UND NORADRENALIN

1964 ◽  
Vol 45 (4) ◽  
pp. 641-646 ◽  
Author(s):  
Wilhelm Dirscherl ◽  
Betty Brisse
Keyword(s):  
Melting Point ◽  
Rat Liver ◽  
Vanillic Acid ◽  
Human Liver ◽  
Mandelic Acid ◽  
Post Mortem ◽  
The Third ◽  
Uv And Ir Spectra ◽  
Solvent Systems ◽  
Liver Homogenates

ABSTRACT Incubation of homogenates of rat liver or human liver with D,L-3-methoxy-4-hydroxy-mandelic acid yielded 3 diazopositive compounds. In addition to the starting material, vanillic acid could be isolated by means of column chromatography. It was identified by the shape of its crystals, micro melting point, mixed melting point, UV- and IR-spectra, and paper chromatography in 3 different solvent systems. The third substance has not yet been identified. Since acid hydrolysis does not result in any cleavage a conjugate can be ruled out. The yield of vanillic acid was about 12 per cent with rat liver, 3 per cent with post mortem liver and 7-8 per cent with liver obtained at operation. Vanillic acid is not further metabolized by liver homogenates and can also be considered as the final metabolite of adrenaline and noradrenaline in the human liver.

Effect of prolonged cold exposure on oxidative phosphorylation and adenosinetriphosphatase activity of rat liver tissue

1959 ◽  
Vol 196 (4) ◽  
pp. 890-892 ◽  
Author(s):  
John P. Hannon
Keyword(s):  
Oxidative Phosphorylation ◽  
Rat Liver ◽  
Cold Exposure ◽  
Liver Tissue ◽  
Exposed Group ◽  
Lower Activity ◽  
Significant Lowering ◽  
Liver Homogenates ◽  
Calcium And Magnesium

Liver homogenates from control and one month cold-exposed (5 ± 1°C) rats were assayed for the P/O ratios characteristic of succinate and ß-hydroxybutyrate oxidations and for the level of adenosinetriphosphatase activity. With both substrates a significant lowering of the P/O ratio was observed in the cold-exposed group. Measurements of adenosinetriphosphatase activity in water homogenates showed that calcium and magnesium had strong activating effects. Little difference was found between control and experimental preparations except where both ions were used simultaneously. Here, the tissue from the cold-exposed group exhibited a slightly lower activity than the controls.

Uptake, metabolism and subcellular distribution of [125I]T4 in calf thyroid slices

1984 ◽  
Vol 105 (3) ◽  
pp. 341-349 ◽  
Author(s):  
G. D. Chazenbalk ◽  
D. L. Kleiman de Pisarev ◽  
G. J. Juvenal ◽  
M. A. Pisarev
Keyword(s):  
Rat Liver ◽  
Paper Chromatography ◽  
Subcellular Distribution ◽  
Inhibitory Action ◽  
Soluble Fraction ◽  
Temperature Dependent ◽  
Liver Slices ◽  
Liver Homogenates

Abstract. Previous work from our laboratory has shown that iodothyronines have a direct inhibitory action on the thyroid. In the present studies the uptake, metabolism and subcellular distribution of labelled thyroxine were analyzed. The entry of this hormone reaches a plateau after 15–20 min incubation and is temperature-dependent. The T/M values for T4 were much lower than those of labelled T3 and the curve was different from that obtained with [125I]. The influence of a series of compounds on the T/M values for thyroxine was studied. KI, T3, IOP PTU and MMI were without effect. Absence of Ca++ in the buffer, or addition of KClO4 or ouabain caused a slight decrease, while TSH produced a stimulation in the T/M ratio. Calf thyroid slices dehalogenated thyroxine, producing both T3 and rT3. TSH increased the generation of these two compounds. Neither PTU nor IOP altered the production of T3 and rT3 significantly. The lack of effect of IOP on T3 and rT3 generation was confirmed in calf thyroid homogenates. However, and in agreement with previous reports, IOP significantly decreased production of both triiodothyronines in rat liver slices and in rat liver homogenates. When the subcellular distribution of labelled thyroxine was examined most of the radioactivity appeared in the soluble fraction and less than 1 % was present in purified nuclei. The addition of unlabelled thyroxine to the slices only caused a significant displacement in the radioactivity of purified nuclei. The presence of labelled thyroxine in the nuclei was confirmed by paper chromatography.

Intensification of the xanthine oxidase activity of rat liver homogenates on storage

1968 ◽  
Vol 46 (9) ◽  
pp. 1047-1056
Author(s):  
D. G. R. Blair ◽  
B. D. McLennan
Keyword(s):  
Xanthine Oxidase ◽  
Rat Liver ◽  
Oxidase Activity ◽  
Enzyme Assay ◽  
Substrate Inhibition ◽  
Temperature Dependent ◽  
Xanthine Oxidase Activity ◽  
Aging Period ◽  
Liver Homogenates ◽  
High Concentrations

The xanthine oxidase activity of rat liver homogenates increased severalfold when the homogenates were stored (aged) at 4 °C for several days. The increase could be demonstrated by measuring xanthine oxidase activity by xanthine utilization or allantoin formation from xanthine. The increase in activity was not correlated with the concentrations of allantoin, uric acid, xanthine, or hypoxanthine in the homogenates, and, therefore, is not attributed to decrease of substrate inhibition, but its demonstration was partially inhibited by relatively high concentrations of xanthine in the enzyme-assay reaction medium.The increase in xanthine oxidase activity was temperature-dependent and was unaffected by the presence of glucose or adenosine 5′-triphosphate. Lysis of unbroken cells during the aging period and microbial contamination were not contributory. Dialysis of a fresh homogenate partially inhibited the increase in activity, but the addition of the dialysate of an aging homogenate to a dialyzed or fresh homogenate did not stimulate activity.The mechanism of the increase in xanthine oxidase activity has not been elucidated, but the fact that stimulation of the activity by methylene blue decreases as the homogenates age, suggests that the rate at which reduced xanthine oxidase is oxidized by air may increase with homogenate aging.

scholarly journals THE INCORPORATION OF THE CARBOXYL CARBON FROM ACETATE INTO CHOLESTEROL BY RAT LIVER HOMOGENATES

1954 ◽  
Vol 206 (1) ◽  
pp. 471-481 ◽  
Author(s):  
Ivan D. Frantz ◽  
Nancy L.R. Bucher ◽  
Henny S. Schneider ◽  
Naomi H. McGovern ◽  
Ruth Kingston
Keyword(s):  
Rat Liver ◽  
Liver Homogenates ◽  
Carboxyl Carbon
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