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PubMed1966

Thiamine pyrophosphate hydrochloride: stereochemical aspects from an x-ray diffraction study.

The crystal structure of thiamine pyrophosphate has been determined by a three-dimensional x-ray analysis. The conformation of the molecule in the crystalline state is determined by the formal charge distribution within the molecule which exists as a zwitterion with the negative pyrophosphate chain folded back over the positive, ring portion of the molecule. The oxygen atoms in the pyrophosphate group are in the staggered conformation when viewed along the phosphorus-phosphorus axis. Even though the pyrophosphate is present in this compound as the monoionized monoester, the configuration is the same as that present in the inorganic pyrophosphate ion. From a comparison of three different crystal structures containing the thiamine moiety and from studies with atomic models, it seems plausible that the basic molecular conformation observed in this crystal is maintained in the catalytically active molecule. Knowledge of the detailed crystal structure provides new insight into the biochemical mechanism of reactions catalyzed by thiamine pyrophosphate.

Diphosphates↗

PubMed2005

Homodimeric hexaprenyl pyrophosphate synthase from the thermoacidophilic crenarchaeon Sulfolobus solfataricus displays asymmetric subunit structures.

Hexaprenyl pyrophosphate synthase (HexPPs) from Sulfolobus solfataricus catalyzes the synthesis of trans-C(30)-hexaprenyl pyrophosphate (HexPP) by reacting two isopentenyl pyrophosphate molecules with one geranylgeranyl pyrophosphate. The crystal structure of the homodimeric C(30)-HexPPs resembles those of other trans-prenyltransferases, including farnesyl pyrophosphate synthase (FPPs) and octaprenyl pyrophosphate synthase (OPPs). In both subunits, 10 core helices are arranged about a central active site cavity. Leu164 in the middle of the cavity controls the product chain length. Two protein conformers are observed in the S. solfataricus HexPPs structure, and the major difference between them occurs in the flexible region of residues 84 to 100. Several helices (alphaI, alphaJ, alphaK, and part of alphaH) and the associated loops have high-temperature factors in one monomer, which may be related to the domain motion that controls the entrance to the active site. Different side chain conformations of Trp136 in two HexPPs subunits result in weaker hydrophobic interactions at the dimer interface, in contrast to the symmetric pi-pi stacking interactions of aromatic side chains found in FPPs and OPPs. Finally, the three-conformer switched model may explain the catalytic process for HexPPs.

Alkyl and Aryl Transferases↗

PubMed2003

Escherichia coli response to exogenous pyrophosphate and analogs.

The addition of exogenous pyrophosphate increases the growth yield and cAMP synthesis in stationary phase when Escherichia coli is grown in minimal medium. Pyrophosphate increases the yield by altering the enterobactin uptake system. We studied the physiological effects and examined how the E. coli transcriptome was modified when two structural analogs of pyrophosphate were added to the growth medium. Methylenediphosphonic acid or a high concentration of iron had the same positive effects as pyrophosphate on growth yield, cAMP synthesis and the repression of Fur-regulated genes. In contrast, imidodiphosphate did not affect these cellular processes significantly. The transcriptome modifications generated by pyrophosphate or methylenediphosphonic acid were more similar than those generated by imidodiphosphate or excess iron. The transcriptome data also indicated that processes other than iron uptake might be involved in the cellular response to exogenous pyrophosphate or methylenediphosphonic acid.

Culture Media↗

PubMed2001

Structural features of nonpeptide prenyl pyrophosphates that determine their antigenicity for human gamma delta T cells.

Human Vgamma2Vdelta2(+) T cells proliferate in vivo during many microbial infections. We have found that Vgamma2Vdelta2(+) T cells recognize nonpeptide prenyl pyrophosphates and alkylamines. We now have defined structural features that determine the antigenicity of prenyl pyrophosphates by testing synthetic analogs for bioactivity. We find that the carbon chain closest to the pyrophosphate moiety plays the major role in determining bioactivity. Changes in this area, such as the loss of a double bond, abrogated bioactivity. The loss of a phosphate from the pyrophosphate moiety also decreased antigenicity 100- to 200-fold. However, nucleotide monophosphates could be added with minimal changes in bioactivity. Longer prenyl pyrophosphates also retained bioactivity. Despite differences in CDR3 sequence, Vgamma2Vdelta2(+) clones and a transfectant responded similarly. Ag docking into a Vgamma2Vdelta2 TCR model reveals a potential binding site in germline regions of the Vgamma2Jgamma1.2 CDR3 and Vdelta2 CDR2 loops. Thus, Vgamma2Vdelta2(+) T cells recognize a core carbon chain and pyrophosphate moiety. This recognition is relatively unaffected by additions at distal positions to the core Ag unit.

Adult↗

PubMedDate not supplied

Anti-calculus effects of dentifrice containing pyrophosphate compared with control.

A 3-month, double-blind, randomized, longitudinal, parallel clinical study was conducted to compare the effects on supragingival calculus deposits of a dentifrice containing soluble pyrophosphate to a control MFP dentifrice, which did not contain pyrophosphates. During the pre-test phase, 247 teachers were examined for presence of calculus on the lingual surfaces of the 6 lower anterior teeth, using the Periodontal Probe Method of Calculus Assessment (Volpe et al. 1965). Statistical methods employed were the two-way analysis of variance as well as the paired and unpaired t tests. The level of statistical significance chosen was p less than 0.05. At the end of the 3-month pre-test phase, 88 candidates with the highest calculus index scores met the initial criteria and were stratified into two balanced groups based on their age and sex. Each group received an oral prophylaxis and participants were assigned to use either the dentifrice containing the pyrophosphate or the MFP and instructed to brush their teeth twice daily at home for the next 3 months (test phase). The results showed that the group using the pyrophosphate dentifrice experienced a 20% greater reduction in calculus formation when compared to the MFP control There was also a greater number of calculus-free subjects and tooth surface sites in the soluble pyrophosphate group. The change in the Volpe-Manhold Index revealed significant differences for both the pyrophosphate group (change = 1.7111; p = 0.0010) as well as, though less prominent, for the control group (change = 1.4186; p = 0.0313).

Adult↗

PubMed1976

Mechanism of localization of 99mTc-labeled pyrophosphate and tetracycline in infarcted myocardium.

The gross and subcellular localizations of 99mTc-labeled pyrophosphate and tetracycline in myocardial infarcts were studied in a rabbit model. Experiments utilizing double-nuclide labeling were carried out using a useful mapping technique. Concentration of the various chelates decreases in an expected manner from the center of the infarcted area toward its periphery, but it is higher near the epicardial surface than toward the endocardium. Technetium-99m-pyrophosphate is concentrated in the same infarcted areas as 45Ca ion or 32P-pyrophosphate, but to a much greater degree. The uptake is dependent on both the degree of necrosis and residual blood flow. Gel filtration experiments with rabbit serum indicate that 99mTc-tagged pyrophosphate, tetracycline, and diphosphonate are mainly protein-bound, whereas 32P-pyrophosphate is not. Subcellular localization studies show that 99mTc-tetracycline and 99mTc-pyrophosphate are bound primarily to soluble protein, and only a small fraction is associated with nuclei, mitochondria, and microsomes. The uptake of technetium chelates in myocardial infarcts may be due to the formation of polynuclear complexes with denatured macromolecules rather than to the deposition of calcium in mitochrondria.

Animals↗

PubMed1972

Thermal and pH stability of 2 -isopentenyl pyrophosphate.

The isoprenoid precursors Delta(3)-isopentenyl pyrophosphate and gamma,gamma-dimethylallyl pyrophosphate (Delta(2)-isopentenyl pyrophosphate) have been separated by thin-layer chromatography. The products from Delta(2)-isopentenyl pyrophosphate incubated under various conditions of pH and temperature have been separated, and the survival of Delta(2)-isopentenyl pyrophosphate under these conditions has been calculated. The acid-labile Delta(2)-isopentenyl pyrophosphate can be stored indefinitely at pH 11.5 and -100 degrees C.

Alkenes↗

PubMed1978

Biosynthesis of P1-di-N-acetyl-alpha-chitobiosyl P2-dolichyl pyrophosphate in calf pancreas microsomes.

Calf pancreas microsomes incubated with UDP-N-acetyl-D-[14C] glucosamine in the presence of Mn2+ incorporated radioactivity into P1-2-acetamido-2-deoxy-D-glucopyranosyl P2-dolichyl pyrophosphate and P1-di-N-acetyl-alpha-chitobiosyl P2-dolichyl pyrophosphate. The formation of both glycolipids was enhanced to the same extent by exogenous dolichyl phosphate. Labeled P1-di-N-acetyl-alpha-chitobiosyl P2-dolichyl pyrophosphate was formed from synthetic P1-2-acetamido-2-deoxy-alpha-D-glucopyranosyl P2-dolichyl pyrophosphate and from prelabeled pancreatic P1-2-acetamido-2-deoxy-alpha-D-glucopyranosyl P2-dolichyl pyrophosphate without the addition of divalent cation. Upon thin layer chromatography, it had the same mobility as synthetic P1-di-N-acetyl-alpha-chitobiosyl P2-dolichyl pyrophosphate recently synthesized by Warren et al. (Warren, C. D., Herscovics, A., and Jeanloz, R. W. (1977) Carbohydr. Res., in press), but was different from the synthetic compound prepared by Wedgwood et al. (Wedgwood, J. F., Warren, C. D., Jeanloz, R. W., and Strominger, J. L. (1974) Proc. Natl. Acad. Sci. U. S. A. 71, 5022-5026).

Animals↗

PubMed1991

Comparison of keratan sulphate concentrations and the size distribution of proteoglycans in the synovial fluid of patients with osteoarthritis and pyrophosphate arthropathy.

In order to evaluate the effect of calcium pyrophosphate dihydrate (CPPD) deposition on articular cartilage catabolism, the proteoglycans released into normal synovial fluid were compared with those in synovial fluid obtained from patients with osteoarthritis (OA), chronic pyrophosphate arthropathy (CPA) and acute pyrophosphate arthropathy (APA). Keratan sulphate (KS) was measured by the modified 1,9-dimethylmethylene blue (DMB) assay in synovial fluids treated with chondroitin ABC lyase. This enzyme was found to eliminate all of the sulphated glycosaminoglycans in synovial fluid except KS. In OA, CPA and APA the concentrations of KS were found to be significantly higher than in normal synovial fluid (NSF) (P less than 0.01). Similar KS concentrations were observed in CPA and APA. In CPA they were significantly higher than in OA (P less than 0.02). The size distribution of proteoglycan fragments varied between different patients with the same disease, but only minor differences were observed in patients with OA and CPA who were matched for age, sex and disease severity. Furthermore, the size distribution of proteoglycan fragments in the acute and chronic phases of pyrophosphate arthritis was similar. Thus although in pyrophosphate arthritis the rate at which proteoglycans are released from the cartilage may be greater than in OA or normal joints, the fundamental processes governing the release of these macromolecules may be the same.

Adult↗

PubMed1987

Effect of glycosaminoglycans on calcium pyrophosphate crystal formation in collagen gels.

Formation of calcium pyrophosphate dihydrate (CPPD) crystals in native collagen gels represent an in vitro model system for the study of pathological cartilage calcification. The conditions under which CPPD forms in collagen gels have been determined. At low Ca X pyrophosphate product, CPPD forms directly. At high Ca X pyrophosphate product, CPPD forms via the amorphous intermediate calcium magnesium pyrophosphate (CMPP). Chondroitin sulfate (CS) inhibits formation of CPPD by both pathways, but apparently by different mechanisms. Direct CPPD formation is inhibited with low potency by CS, apparently by binding of Ca2+ ions. Indirect formation of CPPD is inhibited with high potency by CS, apparently by stabilization of the CMPP intermediate. Comparison of the inhibition of direct CPPD formation by the two glycosaminoglycan species occurring in cartilage proteoglycan showed that CS is a more potent inhibitor than keratan sulfate (KS), in agreement with the greater Ca2+-binding affinity of CS. The increase in KS/CS ration which occurs in human hyaline cartilage with aging may facilitate deposition of CPPD crystals by decreasing the exclusion of pyrophosphate anions.

Calcium Pyrophosphate↗

PubMed1977

The role of bound thiamine pyrophosphate in the synthesis of thiamine triphosphate in rat liver.

Thiamine pyrophosphate-ATP phosphoryltransferase, the enzyme that catalyzes the synthesis of thiamine triphosphate, has been found in the supernatant fraction of rat liver. The substrate for the enzyme is endogenous, bound thiamine pyrophosphate, since the addition of exogenous thiamine pyrophosphate had no effect. Thus, when a rat liver supernatant was incubated with gamma-labelled [32P]ATP, thiamine [32P]triphosphate was formed whereas the incubation of thiamine [32P]pyrophosphate with ATP did not produce thiamine [32P]triphosphate. The endogenous thiamine pyrophosphate was found to be bound to a high molecular weight protein which comes out in the void volume of Sephadex G-75, and is not dialyzable. The activity that catalyzes the formation of thiamine triphosphate has an optimum pH between 6 and 6.5, a linear time course of thiamine triphosphate synthesis up to 30 min, and is not affected by Ca2+, cyclic GMP and sulfhydryl reagents.

Animals↗

PubMed1983

Sensitivity of technetium-99m-pyrophosphate scintigraphy in diagnosing cardiac amyloidosis.

To determine the value of technetium-99m-pyrophosphate myocardial scintigraphy in the diagnosis of amyloid heart disease this procedure was prospectively performed in 20 consecutive patients with biopsy-proven primary amyloidosis. Eleven patients had echocardiographic abnormalities compatible with amyloid cardiomyopathy, 9 of whom had congestive heart failure. Diffuse myocardial pyrophosphate uptake was of equal or greater intensity than that of the ribs in 9 of the 11 patients with echocardiograms suggestive of amyloidosis, but in only 2 of the 9 with normal echocardiograms, despite abnormal electrocardiograms (p less than 0.01). Increased wall thickness measured by M-mode echocardiography correlated with myocardial pyrophosphate uptake (r = 0.68, p less than 0.01). None of 10 control patients with nonamyloid, nonischemic heart disease had a strongly positive myocardial pyrophosphate uptake. Thus, myocardial technetium-99m-pyrophosphate scanning is a sensitive and specific test for the diagnosis of cardiac amyloidosis in patients with congestive heart failure of obscure origin. It does not appear to be of value for the early detection of cardiac involvement in patients with known primary amyloidosis without echocardiographic abnormalities.

Aged↗

PubMed1996

The influence of two bone agents (99Tcm-pyrophosphate and 99Tcm-methylenediphosphonate) on quantitative sacroiliac joint scintigraphy.

Bone scintigraphy is an extremely sensitive method for the detection of focal bone disease. In many hospitals, quantitative sacroiliac joint scintigraphy is still a routine procedure in detecting sacroiliitis. In previous studies, both 99Tcm-methylenediphosphonate (99Tcm-MDP) and 99Tcm-pyrophosphate have been used for bone imaging. 99Tcm-pyrophosphate is eliminated more slowly than 99Tcm-MDP from the circulation and gives a higher background activity. We wished to discover the sacroiliac/sacral ratio (SI/S ratio) changes when using different bone agents. The aim of this study was to evaluate differences in SI/S ratios between the two bone agents. Forty-six control subjects, aged 31-50 years, with no history of back pain, scoliosis, kyphosis, joint pain, arthritis, lesions within the pelvis, chemotherapy or systemic diseases such as diabetes or systemic lupus erythematosis, were included in the study. A posterior planar image of the pelvis was performed to calculate the SI/S ratio 3 h after the injection of 740 MBq 99Tcm-MDP or 99Tcm-pyrophosphate. Twenty-five subjects were studied with 99Tcm-MDP and 21 with 99Tcm-pyrophosphate. We found the SI/S ratios using 99Tcm-MDP to be slightly higher than those using 99Tcm-pyrophosphate, especially on the left side, but this difference was not statistically significant (P-values > 0.1 on both sides using Student's t-tests for unpaired data).

Adult↗

PubMed1987

Technetium pyrophosphate labelling following catheter shock: potential for a new intraoperative mapping technique.

Technetium pyrophosphate uptake at the site of catheter shock was studied in four patients and seven experimental dogs. Technetium pyrophosphate scintigraphy was performed following five catheter ablation attempts in humans at different cardiac sites, and following 24 J catheter shocks delivered in the right and left ventricles of seven dogs. In the patients, gamma camera imaging with tomographic reconstruction showed intense focal uptake at the sites of shock. The scans were positive from 1.5 to 5.5 h following ablation and stayed positive for up to five days. In the animals, the low energy shocks produced circumscribed areas of coagulation and contraction band necrosis. The binding of technetium pyrophosphate at these sites was confirmed by in vivo gamma camera imaging, epicardial counting with a 1.2 cm scintillation probe and ex vivo imaging. Ratios of focal binding to normal myocardial uptake of technetium pyrophosphate were calculated from the digital gamma camera images. In all cases, technetium pyrophosphate was bound to myocardial sites where transcatheter energies were delivered in both humans and dogs. Intraoperative localization of the origin of tachycardia in man may be facilitated by combining preoperative endocardial catheter mapping, catheter shock, radionuclide labelling of the site of shock and a search for the focus of radionuclide concentration during subsequent surgery.

Aged↗

PubMed1985

Half-of-the-site reactivity of the decarboxylating component of the pyruvate dehydrogenase complex from pigeon breast muscle with respect to 2-hydroxyethyl thiamine pyrophosphate.

The holopyruvate dehydrogenase is characterized by the charge transfer complex formation between tryptophan residue and thiamine pyrophosphate in each of two active centres. Interaction of apoenzyme with one mole of 2-hydroxyethyl thiamine pyrophosphate results in appearance of the same spectral band which does not change in intensity with further increase in ligand concentration. 2-hydroxyethyl thiamine pyrophosphate: acceptor oxidoreductase activity abolishes after oxidation of only one tryptophan residue per mole of the protein or blocking of one of the active centres with inactive analogue of the coenzyme. In the latter case the charge transfer complex band induced by interaction of apoenzyme with 2-hydroxyethyl thiamine pyrophosphate was not shown at all. These facts testify to half-of-the-site reactivity of pyruvate dehydrogenase with respect to 2-hydroxyethyl thiamine pyrophosphate.

Animals↗

PubMedDate not supplied

Calcium pyrophosphate crystal formation in aqueous solutions.

Pseudogout is characterized by the deposition of calcium pyrophosphate dihydrate, triclinic [CPPD(T)] and calcium pyrophosphate dihydrate, monoclinic [CPPD(M)] crystals in articular connective tissues. We studied aqueous solutions over a range of calcium chloride/sodium pyrophosphate concentrations to determine the ionic conditions under which these particular salts form. At 37 degrees C, CPPD(T) forms when [PPi]t greater than or equal to 10(-4), while formation of CPPD(M) occurs at 10(-3) M < [PPi]t less than or equal to 10(-2) M. When [Na+]t > 120 mM, calcium disodium pyrophosphates precipitate. With 1 mM Mg++, CPPD(M) forms at [PPi]t > 10(-3) M, mixed with a calcium magnesium pyrophosphate at [PPi]t greater than or equal to 10(-2) M. We conclude that CPPD(T) and CPPD(M) crystals form in a restricted ratio and range of [Ca++]t and [PPi]t and that other ions, particularly Mg++ and Na+, affect the nature of the crystal products formed.

Calcium Pyrophosphate↗

PubMed1981

[99mTc-pyrophosphate scintigraphic indices at different times in acute myocardial infarct].

The incorporation rate of 99mTc-pyrophosphate into the myocardium was studied in 123 patients with acute myocardial infarction at different stages of the disease. The capacity of the damaged myocardium to accumulate the labelled pyrophosphate decreased with its healing. The accumulation character of the radiopharmacologic preparation also changed. The revealed phenomena are explained by the features of the 99mTc-pyrophosphate concentration mechanisms of the damaged areas of the myocardium. during the necrosis phase pyrophosphate is accumulated in the irreversibly damaged myocardial cells. The incorporation of 99mTc-pyrophosphate into the myocardium at the late stages of the disease are explained by both the presence of the necrotized cells in the myocardium and possible binding of the radiopharmacologic preparation to collagen.

Diphosphates↗

PubMed1995

Quantitative determination of dihydroxyethylthiamine pyrophosphate by the circular dichroism method.

This work is concerned with a convenient and fast method for quantitative determination of dihydroxyethylthiamine pyrophosphate in solution where it is present as the only component or as a mixture with thiamine pyrophosphate (or other optically inactive compounds). The molar coefficient is given for circular dichroism absorption of dihydroxyethylthiamine pyrophosphate. The method for determining thiamine pyrophosphate in the presence of dihydroxyethylthiamine pyrophosphate is described as well.

Anion Exchange Resins↗