Showing papers on "Thiamine published in 1970"

Mechanisms of thiamine-catalyzed reactions. Decarboxylation of 2-(1-carboxy-1-hydroxyethyl)-3,4-dimethylthiazolium chloride.

Abstract: Previous investigations have indicated that the thiamine pyrophosphate-dependent enzymatic decarboxylation of pyruvate to acetaldehyde proceeds via the decarboxylation of 2-(l-carboxy-l-hydroxyethyl)thiamine pyrophosphate (Ia) to 2-(l-hydroxyethyl)thiamine pyrophosphate (IIa). This paper reports the synthesis of an analog of Ia, 2-(l-carboxy-l-hydroxyethyl)-3,4-dimethylthiazolium chloride (CHDT chloride), and the kinetics of the decarboxylation of CHDT to 2-(l-hydroxyethyl)-3,4-dimethylthiazolium ion in water, ethanol-water mixtures, and ethanol. We conclude from the dependence upon pH of the observed first-order rate constants for the decarboxylation of CHDT in water at 67 ' that the reactive species is the one in which the carboxyl group is ionized. The rate of decarboxylation of this dipolar ion is markedly increased in solvents less polar than water; the half-times for decarboxylation are 24.0 hr in water a t 45.6' and 3.2 min in absolute ethanol at 26.0'. Comparison of this model with the pyruvate decarboxylase reaction shows that the enzyme accelerates the decarboxylation of Ia in water by a factor of at least lo5. We propose that the enzymatic catalysis is effected through binding of the thiazolium portion of Ia in a region of the enzyme less polar than water and suggest that such an enzymatic solvent effect is a major cause of catalysis in many thiamine pyrophosphate-dependent enzymatic reactions. he decarboxylation of pyruvate to acetaldehyde by T the enzyme pyruvate decarboxylase is a reaction which requires the coenzyme thiamine pyrophosphate.2 On the basis of investigations of nonenzymatic model reactions, Breslow a proposed that the enzymic reaction proceeds by way of 2-(l-carboxy-l-hydroxyethy1)thiamine pyrophosphate (Ia), which is formed from thiamine pyrophosphate and pyruvic acid by reaction of the thiazolium ring, ionized at carbon 2, with the carbonyl group of pyruvic acid. Decarboxylation of this intermediate yields 2 4 1-hydroxyethy1)thiamine pyrophosphate (IIa), which can then lose acetaldehyde and so regenerate the thiamine pyrophosphate. Subsequently, the proposed intermediate H 0 > N x c H 3 Rl + 3J--cH3 HOZCC R.2 HC '4 & I CH3 I CH3

Improved Synthetic Medium for the Growth of Rhizobium

Abstract: Summary. A modification of Bergersen's synthetic medium gave improved growth of Rhizobium. When potassium was included in the medium the biotin concentration could be decreased from the recommended 150–250 to 0·5 μg/l. Growth of 15 strains from 6 Rhizobium spp. was compared in the original and modified media and the responses of those strains to biotin, thiamine and calcium pantothenate noted.

Nutritional Requirements of Streptococcus mutans

Abstract: Ten strains of Streptococcus mutans, representing four serological groups, have been grown in chemically defined media. For anaerobic growth, one of the strains required the following organic compounds: glucose, cysteine (or thioglycolic acid), biotin, p-aminobenzoic acid, thiamine, riboflavin, pyridoxine, pantothenic acid and nicotinic acid. Except for this vitamin requirement, the organism could use ammonia as the sole source of nitrogen for growth. In aerobic culture, uracil and one of the amino acids, glutamine, glutamic acid, asparagine or aspartic acid, had to be included in the medium for growth of the organism.

Production of vitamin b12, thiamine, and biotin by phytoplankton1

Abstract: SUMMARY Some ecologically important phytoplankters released vitamins into culture medium during growth. Skeletonema costatum and Stephanopyxis turris (vitamin B12-requirers) produced both thiamine (vitamin B1) and biotin when growing with either 12 or 2 ng vitamin B12/liter. Gonyaulax polyedra (vitamin B12-requirer) produced thiamine with 12 ng vitamin B12/liter, and Coccolithus huxleyi (thiamine-requirer) produced vitamin B12 and biotin with 120 ng thiamine/liter, but only biotin with 10 ng thiamine/liter. The amount of vitamin produced by an alga and rate at which it was produced varied with the phytoplankter, the concentration of the required vitamin, and incubation time. Vitamins produced during early and exponential growth were due to excretions, and those produced at stationary growth resulted from excretion and release due to cell lysis. Uptake of the required vitamin by all phytoplankters was greatest during the first few days of incubation. On continued incubation the rate of uptake/cell decreased. In the sea phytoplankters may contribute a major portion of the amount of dissolved vitamins.

Experience with phosphoryl transferase inhibition in subacute necrotizing encephalomyelopathy.

Abstract: A diagnostic test for urinary inhibition of thiamine pyrophosphate-adenosine triphosphate phosphoryl transferase uncovered five definite and three probable cases of subacute necrotizing en...

Thiaminase I in the development of cerebrocortical necrosis in sheep and cattle.

Abstract: MEMBERS of the B group of vitamins are synthesized by ruminal microflora1, and it has therefore been assumed2 that ruminants do not require thiamine in their diet. In Cerebrocortical necrosis of sheep and cattle3, however, tissue thiamine levels are low, resulting in cellular anoxia, characteristic damage to the cortical neurones3, raised blood keto-acids and lactate, and lowered transketolase4 activity. Moreover, plasma pyruvate kinase activity is elevated5, indicating a severe disturbance in carbohydrate metabolism. The decrease in thiamine levels was shown to result from the presence of a thiaminase in the ruminal contents of affected animals6,7, and we have since found this enzyme in all cases of cerebrocortical necrosis examined in this laboratory. It was present not only in the ruminal contents, but throughout the alimentary tract. We have now examined further the nature of this enzyme.

Dixenic culture of Daphnia magna, Straus.

Abstract: 1. Daphnia magna can be grown for at least 200 generations, axenically or in crude cultures, in a defined mineral medium, enriched with vitamin B12 and thiamine and 1 ml/100 of a dilute organic medium, when fed with Chlamydomonas reinhardi and Scenedesmus obliquus.2. The organic enrichment is essential for maintaining continued fertility of D. magna.3. The organic enrichment can be replaced by the addition of pantothenic acid to vitamin B12 and thiamine without lowering the fertility of D. magna.4. The organic enrichment (or the vitamin mixture) does not act directly on D. magna but via the algae by changing their nutritional value for Daphina.5. Addition of vitamins to the medium in which the algal food is grown with crustacea may allow continuous cultures of herbivorous crustacea which are considered difficult to grow.

Peripheral nerve changes in thiamine-deficient rats. An electron microscope study.

Abstract: THE occurrence of distal degeneration or dying-back of long axons in a symmetrical polyneuropathy is usually interpreted as indicating that the primary metabolic disturbance is located within neurons rather than in myelin or in supporting structures in the nerve. Whether this particular pattern of neuronal degeneration is due to a diminished output from the perikaryon of some essential axonal metabolite or to a disturbance in axonal transport devices, or to some other mechanism is not known. It has recently been shown that the fine structure and the rate of flow of axoplasmic proteins in the peripheral nerves in experimental triortho-cresyl phosphate polyneuropathy and experimental acrylamide polyneuropathy 1-3 are affected in different ways in these two dying-back polyneuropathies, and it would appear that more than one subcellular mechanism can lead to distal axonal degeneration. In the following report, the fine structural changes in the peripheral nervous system in thiamine hydrochloride-deficient

Nervous transmission in the superior cervical ganglion of the thiamine-deficient rat.

Abstract: The amplitude of the post-ganglionic potential was measured in isolated preparations of the superior cervical ganglion from rats at different stages of thiamine deficiency. At low frequency stimulation (0·5/sec) a decrease in the post-ganglionic potential amplitude was not observed until the final stages of thiamine deficiency. At high frequency stimulation (20/sec) the post-ganglionic potential of the thiamine-deficient rats showed an early and much more pronounced decrease in comparison with that observed in both normal animals and pair-fed controls. The amplitude and conduction velocity of the different components of the sympathetic cord action potential were unaffected by thiamine deficiency.

[16] Electrophoretic separation and fluorometric determination of thiamine and its phosphate esters

Abstract: Publisher Summary This chapter describes the procedure for assay of thiamine and its phosphate esters. The procedure is a modification of existing methods for electrophoretic separation and subsequent fluorometric determination of thiamine compounds. The advantage of the method lies in both its speed of separation of the compounds and its sensitivity. The chapter describes the separation of thiamine and its phosphate esters on Sepraphore II and illustrates the relationship between fluorescent units and concentration of thiamine triphosphate.

Choreoathetotic movement disorder in alcoholism.

Abstract: A syndrome of choreoathetosis in association with alcoholism has been found in 12 patients. It appeared to occur more often in women, was transient, and may have been associated with alcohol withdrawal. It was not associated with gross liver disease, phenothiazine administration, or familial chorea, and no consistent abnormalities in whole blood thiamine or nicotinic acid, in serum magnesium, or in serum vitamin B12 levels were present.

Effect of heating methods on thiamine retention in fresh or frozen prepared foods

Abstract: SUMMARY— Thiamine retentions were determined in beef stew, chicken a la f or newburg and peas in cream sauce, which ware 11 freshly prepared and held for 1, 2 or 3 he ld 180°F (82.2°) or 2) freshly prepared, frozen at −10°F (−23.3°C) and reheated to reheated using microwaves, infrared heating or boiling water immersion. Similar treatments had the on the thiamine retention in the various products. The average thiamine retentions Boy de n products (based on 100% for the freshly prepared foods) were 93.5% in the frozen-microwave heated products; 90% in the frozen-infrared heated products; 86% in the frozen-immersion hot products versus 78% in the fresh hot products after 1 hr, 74% after 2 hr and 67% after 3 hr.

Transketolase Activity in Uremia

Abstract: Erythrocyte transketolase activity (ETKA) was determined in ten uremics undergoing long-term hemodialysis and in four patients treated with Giordano-Giovanetti diet therapy. Transketolase is an essential enzyme in the pentose phosphate shunt and plays a role in myelin sheath maintenance. Its co-factor is thiamine pyrophosphate. In thiamine deficient states ETKA is depressed. ETKA predialysis was depressed in six chronic uremics, although all received thiamine. Dialysis restored ETKA toward normal. Diet patients had depressed transketolase activity which was not affected by diet therapy despite reduced blood urea nitrogen levels. Uremic plasma inhibited normal ETKA by an average of 31.2%; inhibition was reversed by dialysis. A low weight molecular fraction (

Thiamine Diphosphate and its Catalytic Functions

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Nutritional investigation of phagotrophic protozoa under axenic conditions

Abstract: The organic requirements of the dinoflagellateOxyrrhis marina in amounts (where known) per 108 cells are: acetic acid or ethanol 1.0 g; valine, alanine or L-proline 150 mg; L-proline; biotin; thiamine 3.0µg; vitamin B12 30 ng; ubiquinone or plastoquinone 50µg; and a sterol.

Nutritional studies on yeasts during batch and continuous fermentation. i. changes in vitamin concentrations

Abstract: The changes in the concentrations of eight vitamins were followed during the fermentation of wort by Saccharomyces carlsbergensis in plant scale batch fermentor, pilot tower fermentor and laboratory-size continuous stirred tank reactor. During fermentation in batch fermentor, p-amino benzoic acid concentration increased fivefold, while pantothenate increased threefold with one yeast but showed a slight drop with another. Riboflavin and inositol concentrations changed only slightly; biotin and pyridoxin concentrations decreased two to threefold, but the nicotinic acid and thiamine concentrations dropped ten to twentyfold. The other fermentation systems gave, in general, different values, but trends similar to the changes observed during batch fermentations were evident. The concentrations of nicotinic acid, thiamine and p-amino benzoic acid (one yeast) in the beer at the end of storage had increased one and one-half to twofold over the concentrations at the end of fermentation; the other vitamins showed little change.

[25] Preparation of thiamine derivatives and analogs

Abstract: Publisher Summary This chapter discusses the preparation of a number of thiamine homologs and analogs. For the preparation of pyrimidine, 4-amino-5-bromomethyl-2-methylpyrimidine hydrobromide, the methods of Andersag and Grewe are excellent. And for the preparation of the thiazole, 4-methyl-5-(2-hydroxyethyl)thiazole, the method of Buchmann is outstanding. These methods can be applied to the preparation of a number of thiamine homologs and analogs. A practical method for the preparation of the 4,5-dimethyl compound (V: R = CH 3 ) as well as pyrithiamine is presented in the chapter. The intermediate, thiothiamine, formed by the condensation of 4-amino-5-aminomethyl-2-methylpyrimidine, CS 2 , and 3-acetyl-3-chloro-1-propanol is a water-insoluble crystalline compound and is easily converted by oxidation into thiamine in good yield. This method is very useful not only in the laboratory but also in industry and can be applied to the preparation of thiamine homologs and analogs by allowing the various 5-aminomethylpyrimidines to react with various α-chloroketones.

[23] Transketolase (sedoheptulose-7-phosphate:d-glyceraldehyde-3-phosphate dihydroxyacetonetransferase, EC 2.2.1.1) and the TPP effect in assessing thiamine adequacy

Abstract: Publisher Summary This chapter discusses transketolase and the thiamine pyrophosphate (TPP) effect in assessing thiamine adequacy. The transketolase enzyme is of interest to the nutritionist because thiamine pyrophosphate, the functional form of vitamin B 1 , is its coenzyme. It is one of a series of enzymes in the pentose phosphate pathway, and it is widely distributed in tissues of plants, microorganisms, and animals. The chapter describes the assay for transketolase activity and the TPP effect. The assay has been employed with success in a number of species, both in the study of biological interrelationships of thiamine deficiency and in the assessment of thiamine adequacy in man. A similar semimicroassay is described in the chapter. The macroassay has been adapted for use also under automated conditions. Erythrocyte transketolase activity and the TPP effect present a functional evaluation, which is both sensitive to and specific for thiamine deficiency. It may be used to confirm clinical beriberi or other manifestations such as Wernicke's encephalopathy, to reveal a biochemical defect in marginal vitamin B 1 deficiency, or to differentiate B 1 deficiency from clinically similar diseases of other etiology.