Sugarcane Phosphoribosyl Pyrophosphate Synthetase: Molecular Characterization of a Phosphate-independent PRS

Phosphoribosyl pyrophosphate synthetase (PRS-EC:2.7.6.1) is an important enzyme present in several metabolic pathways, thus forming a complex family of isoenzymes. However, plant PRS enzymes have not been extensively investigated. In this study, a sugarcane prs gene has been characterized from the Sugar Cane Expressed Sequence Tag Genome Project. This gene contains a 984-bp open reading frame encoding a 328-amino acid protein. The predicted amino acid sequence has 77% and 78% amino acid sequence identity to Arabidopsis thaliana and Spinacia oleracea PRS4, respectively. The assignment of sugarcane PRS as a phosphate-independent PRS isoenzyme (Class II PRS) is verified following enzyme assay and phylogenetic reconstruction of PRS homologues. To gain further insight into the structural framework of the phosphate independence of sugarcane PRS, a molecular model is described. This model reveals the formation of two conserved domains elucidating the structural features involved in sugarcane PRS phosphate independence. The recombinant PRS retains secondary structure elements and a quaternary arrangement consistent with known PRS homologues, based on circular dichroism measurements.

Inorganic pyrophosphate-phosphohydrolytic activity associated with rat osseous plate alkaline phosphatase

Purified membrane-bound alkaline phosphatase from rat osseous plate hydrolyzed pyrophosphate in the presence of magnesium ions, with a specific activity of 92.7 U/mg. Optimal apparent pH for pyrophosphatase activity was 8.0 and it remained unchanged on increasing the pyrophosphate concentration. In the absence of magnesium ions the enzyme had a K-m = 88 mu M and V = 36.7 U/mg for pyrophosphate and no inhibition by excess substrate was observed. Pyrophosphatase activity was rapidly destroyed at temperatures above 40 degrees C, but magnesium ions apparently protected the enzyme against danaturation. Sodium metavanadate (Ki = 1.0 mM) was a competitive inhibitor of pyrophosphatase activity, while levamisole (Ki = 8.2 mM) and theophylline (Ki = 7.4 mM) were uncompetitive inhibitors. Magnesium ions (K-0.5 = 1.7 mu M) stimulated pyrophosphatase activity, while cobalt (Ki = 48.5 mu M) and zinc (Ki = 22.0 mu M) ions were non-competitive inhibitors. Manganese and calcium ions had no effect on pyrophosphatase activity. The M-w of the pyrophosphatase: protein was 130 kDa by gel filtration, but a value of 65 kDa was obtained by dissociative gel electrophoresis, suggesting that it was a dimer of apparently identical subunits. These results suggested that pyrophosphatase activity stems from the membrane-bound osseous plate alkaline phosphatase and not from a different protein.

Thermal, structural and optical properties of new tungsten lead-pyrophosphate glasses

Crystalline lead-pyrophosphate precursor was prepared in aqueous solution from lead nitrate and phosphoric acid and characterized by X-ray diffraction, thermogravimetry and Raman scattering. This crystalline lead-phosphate was then used to prepare glass samples in the binary system Pb(2)P(2)O(7)-WO(3). Dependence of WO(3) content on thermal, structural and optical properties were investigated by thermal analysis (DSC), Raman spectroscopy, UV-visible and near-infrared absorption and M-Line technique to access refractive index values. Incorporation of WO(3) in the lead-pyrophosphate matrix enhances the glass transition temperature and thermal stability against devitrification, favors formation of P-O-W bonds and WO(6) clusters. In addition, optical properties are strongly modified with a redshift of the optical bandgap with WO(3) incorporation as well as an increase of the refractive index from 1.89 to 2.05 in the visible. (C) 2011 Elsevier B.V. All rights reserved.

Putative pyrophosphate phosphofructose 1-kinase genes identified in sugarcane may be getting energy from pyrophosphate

Pyrophosphate-dependent phosphofructokinase (PPi-PFK) has been detected in several types of plant cells, but the gene has not been reported in sugar cane. Using Citrux paradixi PPi-PFK gene (AF095520 and AF095521) sequences to search the sugar cane EST database, we have identified both the α and β subunits of this enzyme. The deduced amino acid sequences showed 76 and 80% similarity with the corresponding α and β subunits of C. paradisi. A high degree of similarity was also observed among the PFK β subunits when the alignment of the sugar cane sequences was compared to those of Ricinus communis and Solanum tuberosum, it appears that α and β are two distinct subunits; they were found at different concentrations in several sugar cane tissues. It remains to be determined if the different gene expression levels have some physiological importance and how they affect sucrose synthesis, export, and storage in vacuoles. A comparison between the amino acid sequences of β PFKs from a variety of organisms allowed us to identify the two critical Asp residues typical of this enzyme's activity site and the other binding sites; these residues are tightly conserved in all members of this protein family. Apparently, there are catalytic residues on the β subunit of the pyrophosphate-dependent enzyme.

Nonlinear Optical Properties of Tungsten Lead-Pyrophosphate Glasses Containing Metallic Copper Nanoparticles

We have prepared heavy metal oxide glasses containing metallic copper nanoparticles with promising nonlinear optical properties which were determined by Z-scan and pump-probe measurements using femtosecond laser pulses. For the wavelengths within the plasmon band, we have observed saturable absorption and response times of 2.3 ps. For the other regions of the spectrum, reverse saturable absorption and lifetimes shorter than 200 fs were verified. The nonlinear refractive index is about 2.0 × 10-19 m2/W from visible to telecom region, thus presenting an enhancement effect at wavelengths near the plasmon and Cu+2 d-d band. © 2013 Springer Science+Business Media New York.

Third-order nonlinearities and other properties of molybdenum lead-pyrophosphate glass

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Farnesol is utilized for isoprenoid biosynthesis in plant cells via farnesyl pyrophosphate formed by successive monophosphorylation reactions

The ability of Nicotiana tabacum cell cultures to utilize farnesol (F-OH) for sterol and sesquiterpene biosynthesis was investigated. [3H]F-OH was readily incorporated into sterols by rapidly growing cell cultures. However, the incorporation rate into sterols was reduced by greater than 70% in elicitor-treated cell cultures whereas a substantial proportion of the radioactivity was redirected into capsidiol, an extracellular sesquiterpene phytoalexin. The incorporation of [3H]F-OH into sterols was inhibited by squalestatin 1, suggesting that [3H]F-OH was incorporated via farnesyl pyrophosphate (F-P-P). Consistent with this possibility, N. tabacum proteins were metabolically labeled with [3H]F-OH or [3H]geranylgeraniol ([3H]GG-OH). Kinase activities converting F-OH to farnesyl monophosphate (F-P) and, subsequently, F-P-P were demonstrated directly by in vitro enzymatic studies. [3H]F-P and [3H]F-P-P were synthesized when exogenous [3H]F-OH was incubated with microsomal fractions and CTP. The kinetics of formation suggested a precursor–product relationship between [3H]F-P and [3H]F-P-P. In agreement with this kinetic pattern of labeling, [32P]F-P and [32P]F-P-P were synthesized when microsomal fractions were incubated with F-OH and F-P, respectively, with [γ-32P]CTP serving as the phosphoryl donor. Under similar conditions, the microsomal fractions catalyzed the enzymatic conversion of [3H]GG-OH to [3H]geranylgeranyl monophosphate and [3H]geranylgeranyl pyrophosphate ([3H]GG-P-P) in CTP-dependent reactions. A novel biosynthetic mechanism involving two successive monophosphorylation reactions was supported by the observation that [3H]CTP was formed when microsomes were incubated with [3H]CDP and either F-P-P or GG-P-P, but not F-P. These results document the presence of at least two CTP-mediated kinases that provide a mechanism for the utilization of F-OH and GG-OH for the biosynthesis of isoprenoid lipids and protein isoprenylation.

Mammalian inositol polyphosphate multikinase synthesizes inositol 1,4,5-trisphosphate and an inositol pyrophosphate

Using a consensus sequence in inositol phosphate kinase, we have identified and cloned a 44-kDa mammalian inositol phosphate kinase with broader catalytic capacities than any other member of the family and which we designate mammalian inositol phosphate multikinase (mIPMK). By phosphorylating inositol 4,5-bisphosphate, mIPMK provides an alternative biosynthesis for inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. mIPMK also can form the pyrophosphate disphosphoinositol tetrakisphosphate (PP-InsP4) from InsP5. Additionally, mIPMK forms InsP4 from Ins(1,4,5)P3 and InsP5 from Ins(1,3,4,5)P4.

Interleukin 1 beta suppresses transforming growth factor-induced inorganic pyrophosphate (PPi) production and expression of the PPi-generating enzyme PC-1 in human chondrocytes.

Articular cartilage chondrocytes have the unique ability to elaborate large amounts of extracellular pyrophosphate (PPi), and transforming growth factor beta (TGF beta) appears singular among cartilage regulatory factors in stimulating PPi production. TGF beta caused a time and dose-dependent increase in intracellular and extracellular PPi in human articular chondrocyte cultures. TGF beta and interleukin 1 beta (IL-1 beta) antagonistically regulate certain chondrocyte functions. IL-1 beta profoundly inhibited basal and TGF beta-induced PPi elaboration. To address mechanisms involved with the regulation of PPi synthesis by IL-1 beta and TGF beta, we analyzed the activity of the PPi-generating enzyme NTP pyrophosphohydrolase (NTPPPH) and the PPi-hydrolyzing enzyme alkaline phosphatase. Human chondrocyte NTPPPH activity was largely attributable to plasma cell membrane glycoprotein 1, PC-1. Furthermore, TGF beta induced comparable increases in the activity of extracellular PPi, intracellular PPi, and cellular NTPPPH and in the levels of PC-1 protein and mRNA in chondrocytes as well as a decrease in alkaline phosphatase. All of these TGF beta-induced responses were completely blocked by IL-1 beta. Thus, IL-1 beta may be an important regulator of mineralization in chondrocytes by inhibiting TGF beta-induced PPi production and PC-1 expression.

The thermal expansion of uranium pyrophosphate and of ceramic bodies in the system UO-UPO; internal research,

Cover title.

Beitrage zur kenntniss der pyrophosphate.

Thesis (doctoral)--

Force determinants of sit-to-stand transfer in patients with haemophilic arthropathy: Cross-sectional study

SIN FINANCIACIÓN

Relationship of joint deterioration with the generation of muscle strength in patients with hemophilic arthropathy. An observational study

SIN FINANCIACIÓN

Design of a myofascial therapy protocol for the treatment of hemophilic arthropathy of the knee and ankle

Hemophilic arthropathy limits daily life activities of patients with hemophilia, presenting with clinical manifestations such as chronic pain, limited mobility, or muscular atrophy. Although physical therapy is considered essential for these patients, few clinical studies have demonstrated the efficacy and safety of the various physiotherapy techniques. Physical therapy may be useful for treating hemophilic arthropathy by applying safe and effective techniques. However, it is necessary to create protocols for possible treatments to avoid the risk of bleeding in these patients. This article describes the musculoskeletal pathology of hemophilic arthropathy and characteristics of fascial therapy. This systematic protocol for treatment by fascial therapy of knee and ankle arthropathy in patients with hemophilia provides an analysis of the techniques that, depending on their purpose and methodology, can be used in these patients. Similarly, the protocol's applicability is analyzed and the steps to be followed in future research studies are described. Fascial therapy is a promising physiotherapy technique for treating fascial tissue and joint contractures in patients with hemophilic arthropathy. More research is needed to assess the efficacy and safety of this intervention in patients with hemophilia, particularly with randomized multicenter clinical trials