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PubMed1974

Genetic transformation of biosynthetically defective Neisseria gonorrhoeae clinical isolates.

Deoxyribonucleic acid (DNA) and chemically defined media were used in transformation tests of 51 strains of Neisseria gonorrhoeae which exhibited various biosynthetic defects when isolated from patients. These auxotrophic gonococci had one or more nutritional requirements involving proline, methionine, arginine, hypoxanthine, uracil, and thiamine pyrophosphate (THPP). DNA from a clinical isolate which did not require these compounds for growth on defined medium transformed each of the auxotrophic markers of all 51 recipient populations. Ten isolates had defects involving the synthesis of THPP; four strains (designated Thp(-)) had a growth requirement that was satisfied only by THPP, whereas the requirement of six strains (designated Thi(-)) was satisfied by either thiamine or THPP. DNA from Thp(-) donors elicited transformation of Thp(-) as well as Thi(-) recipients. Reciprocally, DNA from a Thi(-) donor transformed both Thi(-) and Thp(-) recipients. Furthermore, DNA from other auxotrophic gonococci had transforming activity for some phenotypically similar auxotrophic recipients. The findings indicate the existence of various nonidentical genetic defects which block reactions in the biosynthesis of proline, methionine, arginine, hypoxanthine, and THPP. Routine cultures from patients with gonorrhea were the source of these auxotrophic strains of N. gonorrhoeae; the various nutritional requirements were identified by a recently described system of gonococcal auxotyping. The transformation test results verify the hereditary basis of the auxotypes, establish that many different mutations exist in potentially virulent gonococci, and illustrate the value of these auxotrophic mutants for studies of the genetic structure and evolution of natural populations of gonococci.

Arginine↗
PubMed1997

In vivo study of the kinetics of thiamine and its phosphoesters in the deafferented rat cerebellum.

The effects of chemical (CD) and surgical (SD) deafferentation of the cerebellum on different steps of the metabolism of thiamine (Th), thiamine monophosphate (ThMP) and thiamine pyrophosphate (ThPP) were evaluated in vivo in rats. CD was carried out by i.p. injection of 3-acetylpyridine, followed by harmaline and niacinamide. SD was carried out by complete dissection of the peduncles of the left cerebellar hemisphere. Under steady state condition the radioactivity of Th and its phosphoesters was determined in plasma and whole cerebellum after an i.p. injection of thiazole-[2(14)C]-thiamine (30 micrograms:1.25 micro Ci). Analytical data were processed by using an improved mathematical compartmental model, which allowed the calculation of fractional rate constants (FRC), turnover rates (TR) and turnover times (TT). Both CD and SD caused a significant reduction of TR values for Th phosphorylation to ThPP, dephosphorylation of ThPP to ThMP and Th, and ThMP, but not Th, release. TT for all Th compounds were increased compared to controls, indicating a general slowing of thiamine metabolism in the deafferented cerebellum. These results indicate an imbalance in the thiamine metabolism resulting from the impaired activity of cerebellar neurons. The possible implications of the changes in rate of Th compound turnover with respect to biochemical changes in cerebellar ataxia are discussed.

Afferent Pathways↗
PubMed1983

Protection against misonidazole-induced neuropathy in rats: a biochemical assessment.

A biochemical method for assessing the chemically induced neurotoxicity of misonidazole (MISO) in the rat has been used to assess whether the concurrent administration of thiamine, thiamine pyrophosphate (TPP) or vitamin E (Vit.E) could afford protection against the neurotoxic side effects of the drug. The tissues analysed were distal sections of the sciatic/posterior tibial nerve (SPTN), trigeminal ganglia and cerebellum. MISO was administered i.p. to Wistar rats at a dose of 400 mg/kg per day for 7 consecutive days to produce the maximal measurable enzyme changes after 4 weeks. The concurrent i.p. and i.m. dosing of thiamine (0.1-100 mg/kg) for 15 consecutive days did not abate the subsequent PNS and CNS enzyme changes. However, with concurrent i.m. dosing of 1.0 mg/kg TPP or p.o. dosing of vitamin E (30 mg/kg) afforded some protection against both the PNS and CNS MISO-induced neurotoxic side effects as measured biochemically.

Animals↗
PubMed2006

Thiamin biosynthesis in eukaryotes: characterization of the enzyme-bound product of thiazole synthase from Saccharomyces cerevisiae and its implications in thiazole biosynthesis.

The biosynthesis of thiamin pyrophosphate in eukaryotes is different from the prokaryotic biosynthesis and is poorly understood to date. Only one thiazole biosynthetic gene has been identified (Thi4 in Saccharomyces cerevisiae). Here we report the identification and characterization of a Thi4-bound metabolite that consists of the ADP adduct of 5-(2-hydroxyethyl)-4-methylthiazole-2-carboxylic acid. The unexpected structure of this compound yields the first insights into the mechanism of thiamin thiazole biosynthesis in eukaryotes.

Binding Sites↗
PubMed1996

Thiamine deficiency as predisposition to, and consequence of, increased alcohol consumption.

It was found that the activity of the marker thiamine-dependent enzyme, transketolase (TK), was decreased (down to 61-79% of control) in blood, liver and brain of inbred rats following a 6-month consumption of 15% ethanol as their only source of drinking fluid. After ethanol withdrawal, the enzyme activity was gradually restored, but did not reach the control values until 1 month following cessation of alcohol consumption. Moreover, in rats preferring ethanol, the decrease of TK activity was more pronounced than in water-preferring rats. Another experiment showed that thiamine deficiency induced by the thiamine antagonist, oxythiamine (200 mg/kg), led to a prolonged increase of the preferential intake of ethanol solutions in inbred rats. Significantly lower liver TK activities and thiamine pyrophosphate content were found in Finnish AA line rats as opposed to ANA line rats which had been obtained by selective outbreeding for high and low voluntary alcohol intake, respectively. Significantly lower TK activity was also found in the whole brain (89%), cerebellum (79%) and pons-medulla oblongata (87%) of AA rats as compared to ANA animals. Our own findings and the literature data confirm the hypothesis that thiamine deficiency can be both predisposing to and a consequence of, increased alcohol consumption.

Alcoholism↗
PubMed1983

Erythrocyte transketolase activity in protein-energy malnutrition.

Erythrocyte transketolase activity (ETKA) and the percentage thiamine pyrophosphate (TPP) effects have been measured in a group of 10 healthy children and 50 malnourished subjects (23 oedematous and 27 non-oedematous cases). The observed ETKA values and percentage TPP effects for the two malnourished groups of subjects differed significantly (P less than 0.001) from the values for the control group. These values reverted almost to normal in 24 subjects who were re-tested after 6 weeks of thiamine therapy. Suggestions are made for this apparent biochemical thiamine deficiency without manifestations in these subjects.

Child, Preschool↗
PubMed1984

The decarboxylation of 3-mercaptopyruvate to 2-mercaptoacetate.

Rat brain mitochondria were found to convert 3-mercaptopyruvate to 2-mercaptoacetate in the presence of NAD+, coenzyme A and thiamin pyrophosphate. The overall reaction probably consists of an oxidative decarboxylation of 3-mercaptopyruvate with 2-mercaptoacetyl CoA as a product which is then hydrolyzed to 2-mercaptoacetate by acyl CoA hydrolase.

Animals↗
PubMed1994

Biochemical and pathological findings on sheep and calves dying of experimental cerebrocortical necrosis.

For observing biochemical and morphopathological changes in experimental cerebrocortical necrosis, 6 sheep and 6 calves were given amprolium (600 mg/kg/day). All of the amprolium-dosed animals showed neurological signs and died on days 35 to 57 after the onset of daily administration. They were pathologically confirmed as cerebrocortical necrosis. Total thiamine levels in blood and tissues were markedly reduced at death. Blood total thiamine level decreased significantly on day 7 of amprolium administration, and reached to the level as low as that seen at death about 2 weeks before the onset of abnormal electroencephalograms. Significant decrease in a thiamine-dependent enzyme, erythrocyte transketolase activity, and increase in thiamine pyrophosphate effect were detected about 2 weeks before the onset of abnormal electroencephalograms. Pathological changes and cerebral autofluorescence observed under ultraviolet light were also examined at death.

Amprolium↗
PubMed1992

DNA sequence of the yeast transketolase gene.

Transketolase (EC 2.2.1.1) is the enzyme that, together with aldolase, forms a reversible link between the glycolytic and pentose phosphate pathways. We have cloned and sequenced the transketolase gene from yeast (Saccharomyces cerevisiae). This is the first transketolase gene of the pentose phosphate shunt to be sequenced from any source. The molecular mass of the proposed translated protein is 73,976 daltons, in good agreement with the observed molecular mass of about 75,000 daltons. The 5'-nontranslated region of the gene is similar to other yeast genes. There is no evidence of 5'-splice junctions or branch points in the sequence. The 3'-nontranslated region contains the polyadenylation signal (AATAAA), 80 base pairs downstream from the termination codon. A high degree of homology is found between yeast transketolase and dihydroxyacetone synthase (formaldehyde transketolase) from the yeast Hansenula polymorpha. The overall sequence identity between these two proteins is 37%, with four regions of much greater similarity. The regions from amino acid residues 98-131, 157-182, 410-433, and 474-489 have sequence identities of 74%, 66%, 83%, and 82%, respectively. One of these regions (157-182) includes a possible thiamin pyrophosphate (TPP) binding domain, and another (410-433) may contain the catalytic domain.

Aldehyde-Ketone Transferases↗
PubMed1970

Mitochondrial longevity in vitro: the retention of respiratory control.

Isolated mitochondria were maintained metabolically active and coupled, i.e., capable of respiratory control, for several hours at 25 degrees C. An increase in respiratory control generally occurred during the first 4-8 hr of incubation followed thereafter by a decline. Longevity is a dynamic function as evidenced by its dependency on substrate and cofactors, thiamine pyrophosphate, in particular. Magnesium was also essential to longevity; coenzyme A, bovine serum albumin, and reducing agents were not. The findings are discussed in terms of cytoplasmic-mitochondrial interrelationships and mitochondrial autonomy.

Adenine Nucleotides↗
PubMed1999

Factors affecting the formation of spherical bodies in the spirochete Treponema denticola.

The oral spirochete Treponema denticola typically is a helically shaped, motile bacterial cell. However, morphological variations of T. denticola cells in the form of "spherical bodies" are sometimes seen. Little is known about the environmental factors that cause their formation. The effects of oxygen, growth temperature, nutrient depletion and the addition of metabolic end-products were tested to determine their role in the morphogenesis of the spherical bodies. It was found that the age of the culture, the omission of individual components (yeast extract, rabbit serum, volatile fatty acids or thiamine pyrophosphate) from the medium and the addition of the metabolic end product lactic acid enhanced the formation of these bodies. However, their formation was decreased upon omission of the medium components asparagine and sodium bicarbonate.

Adaptation, Physiological↗
PubMedDate not supplied

[Thiamine metabolism in experimental hepatitis and the intake of Naftusia mineral water].

The level and metabolism of vitamin B1 and its coenzymic form were studied in the tissues and subcellular structures of the internal organs of white rats with experimental toxic hepatitis, receiving mineral water naphtusya. It was found that naphtusya given per os stimulated the metabolism of thiamine pyrophosphate (TPP), enhanced its concentration in the hepatic tissue and intestinal mucosa, producing a stabilizing effect on the TPP activity. It is concluded that the mineral water naphtusya can be used for enteral correction of vitamin balance in hepatitis patients.

Animals↗
PubMed1984

Thiamine pyrophosphatase and nucleoside diphosphatase in rat brain.

Two types of nucleoside diphosphatase were found in rat brain. One (Type L) had similar properties to those of the liver microsomal enzyme with respect to its isoelectric point, substrate specificity, Km values, optimum pH, activation by ATP and molecular weight. The other (Type B), which separated into multiple forms on isoelectric focusing, had lower Km values and a smaller molecular weight than the Type L enzyme, and was inhibited by ATP. The Type B enzyme catalyzed the hydrolysis of thiamine pyrophosphate as well as those of various nucleoside diphosphates at physiological pH, while Type L showed only nucleoside diphosphatase activity at neutral pH. These findings suggest that the two enzymes play different physiological roles in the brain.

Acid Anhydride Hydrolases↗
PubMed1984

Measurements of B1, B2, B6 status in children and their mothers attending a well-baby clinic in Bangkok.

The status of thiamin, riboflavin and pyridoxine in 717 healthy children aged 1-60 months and 569 mothers aged 16-45 years attending a well-baby clinic in Bangkok were determined by using the erythrocyte enzymes, transketolase, glutathione oxidoreductase, aspartate aminotransferase and measuring the degree of stimulation with the coenzymes thiamin pyrophosphate, flavin adenine dinucleotide and pyridoxal phosphate respectively. Cut-off points for the upper limit of the normal ranges for the respective activation coefficients were established from the data obtained.

Adolescent↗
PubMed1969

Control of the citric acid cycle by glyoxylate. The mechanism of inhibition of oxoglutarate dehydrogenase, isocitrate dehydrogenase and aconitate hydratase.

1. The effects of glyoxylate on partially purified preparations of aconitate hydratase, isocitrate dehydrogenase and oxoglutarate dehydrogenase were compared with those of oxalomalate and hydroxyoxoglutarate (obtained by condensation of glyoxylate with oxaloacetate and pyruvate respectively). 2. Glyoxylate (1mm) did not affect aconitate hydratase and isocitrate dehydrogenase, whereas oxalomalate (1mm) inhibited the enzyme activities completely. 3. Glyoxylate (0.025mm) inhibited oxoglutarate dehydrogenase irreversibly, whereas the same concentrations of oxalomalate and hydroxyoxoglutarate were ineffective. This inhibitory effect was prevented if oxoglutarate, pyruvate or oxaloacetate was mixed with the enzyme before the glyoxylate. 4. Incubation of oxoglutarate dehydrogenase with radioactive glyoxylate produced radioactive carbon dioxide; radioactivity was also recovered in the portion of the enzyme identified with thiamin pyrophosphate. 5. The behaviour of glyoxylate in producing multiple inhibitions of the citric acid cycle, either by direct interaction with oxoglutarate dehydrogenase, or by means of its condensation compounds which inhibit aconitate hydratase and isocitrate dehydrogenase, is discussed.

Animals↗
PubMedDate not supplied

Review: the role of coenzymes in clinical enzymology.

Coenzymes participate in many of the enzyme analyses performed in the clinical laboratory. Supplementation of assay systems with optimal levels of coenzymes has recently been recommended as part of efforts to achieve interlaboratory standardization of enzyme measurements. Aspartate aminotransferase and alanine aminotransferase require pyridoxal phosphate for expression of enzyme activity. The role of this coenzyme in enzymatic transamination and the effects of its supplementation on the clinical estimation of these two enzymes is reviewed. Other coenzymes discussed are flavins, coenzymes for glutathione reductase, glucose oxidase, cholesterol oxidase and diaphorase, as well as thiamine pyrophosphate, coenzyme for transketolase. Catalase and peroxidase are used as examples of hemoproteins utilized in clinical measurements. Two peptide coenzymes, colipase and glutathione, are also considered. Measurement of apoenzyme stimulation upon supplementation with specific coenzymes is discussed as a valuable technique for quantitative coenzyme measurements or assessment of vitamin nutritional status.

Clinical Enzyme Tests↗