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2.
Clin Exp Immunol ; 202(1): 28-46, 2020 10.
Article in English | MEDLINE | ID: mdl-32562256

ABSTRACT

Bronchial asthma is believed to be provoked by the interaction between airway inflammation and remodeling. Airway remodeling is a complex and poorly understood process, and controlling it appears key for halting the progression of asthma and other obstructive lung diseases. Plants synthesize a number of valuable compounds as constitutive products and as secondary metabolites, many of which have curative properties. The aim of this study was to evaluate the anti-remodeling properties of extracts from transformed and transgenic Leonurus sibiricus roots with transformed L. sibiricus roots extract with transcriptional factor AtPAP1 overexpression (AtPAP1). Two fibroblast cell lines, Wistar Institute-38 (WI-38) and human fetal lung fibroblast (HFL1), were incubated with extracts from transformed L. sibiricus roots (TR) and roots with transcriptional factor AtPAP1 over-expression (AtPAP1 TR). Additionally, remodeling conditions were induced in the cultures with rhinovirus 16 (HRV16). The expressions of metalloproteinase 9 (MMP)-9, tissue inhibitor of metalloproteinases 1 (TIMP-1), arginase I and transforming growth factor (TGF)-ß were determined by quantitative polymerase chain reaction (qPCR) and immunoblotting methods. AtPAP1 TR decreased arginase I and MMP-9 expression with no effect on TIMP-1 or TGF-ß mRNA expression. This extract also inhibited HRV16-induced expression of arginase I, MMP-9 and TGF-ß in both cell lines (P < 0·05) Our study shows for the first time to our knowledge, that transformed AtPAP1 TR extract from L. sibiricus root may affect the remodeling process. Its effect can be attributed an increased amount of phenolic acids such as: chlorogenic acid, caffeic acid or ferulic acid and demonstrates the value of biotechnology in medicinal research.


Subject(s)
Airway Remodeling/drug effects , Antigens, Differentiation/biosynthesis , Fibroblasts/metabolism , Gene Expression Regulation/drug effects , Leonurus/chemistry , Plant Extracts/pharmacology , Plant Roots/chemistry , Cell Line , Female , Humans , Plant Extracts/chemistry
3.
J Chem Phys ; 152(12): 124101, 2020 Mar 31.
Article in English | MEDLINE | ID: mdl-32241125

ABSTRACT

DFTB+ is a versatile community developed open source software package offering fast and efficient methods for carrying out atomistic quantum mechanical simulations. By implementing various methods approximating density functional theory (DFT), such as the density functional based tight binding (DFTB) and the extended tight binding method, it enables simulations of large systems and long timescales with reasonable accuracy while being considerably faster for typical simulations than the respective ab initio methods. Based on the DFTB framework, it additionally offers approximated versions of various DFT extensions including hybrid functionals, time dependent formalism for treating excited systems, electron transport using non-equilibrium Green's functions, and many more. DFTB+ can be used as a user-friendly standalone application in addition to being embedded into other software packages as a library or acting as a calculation-server accessed by socket communication. We give an overview of the recently developed capabilities of the DFTB+ code, demonstrating with a few use case examples, discuss the strengths and weaknesses of the various features, and also discuss on-going developments and possible future perspectives.

4.
J Environ Manage ; 198(Pt 1): 277-288, 2017 Aug 01.
Article in English | MEDLINE | ID: mdl-28477569

ABSTRACT

A key component of California's cap-and-trade program is the use of carbon offsets as compliance instruments for reducing statewide GHG emissions. Under this program, offsets are tradable credits representing real, verifiable, quantifiable, enforceable, permanent, and additional reductions or removals of GHG emissions. This paper focuses on the permanence and additionality standards for offset credits as defined and operationalized in California's Compliance Offset Protocol for U.S. Forest Projects. Drawing on a review of the protocol, interviews, current offset projects, and existing literature, we discuss how additionality and permanence standards relate to project participation and overall program effectiveness. Specifically, we provide an overview of offset credits as compliance instruments in California's cap-and-trade program, the timeline for a forest offset project, and the factors shaping participation in offset projects. We then discuss the implications of permanence and additionality at both the project and program levels. Largely consistent with previous work, we find that stringent standards for permanent and additional project activities can present barriers to participation, but also, that there may be a trade-off between project quality and quantity (i.e. levels of participation) when considering overall program effectiveness. We summarize what this implies for California's forest offset program and provide suggestions for improvements in light of potential program diffusion and policy learning.


Subject(s)
Conservation of Natural Resources , Forestry , California , Carbon , Forests
5.
J Mater Chem B ; 5(24): 4690-4696, 2017 Jun 28.
Article in English | MEDLINE | ID: mdl-32264311

ABSTRACT

Self-assembly of a tetrapeptide covalently attached to a thiophene-based monomer produced a gel with a fibrous, porous structure. Conditions were identified in which the thiophene end groups could undergo polymerization while retaining the 3D structure, resulting in the formation of nanofibrous gels with conductivities averaging 10-4 S cm-1.

6.
Biofabrication ; 7(1): 015011, 2015 Mar 02.
Article in English | MEDLINE | ID: mdl-25727172

ABSTRACT

Albumin is rarely used for electrospinning because it does not form fibres in its native globular form. This paper presents a novel method for electrospinning human albumin from a solution containing pharmaceutical grade protein and 25% polyethylene oxide (PEO) used as the fibre-forming agent. After spontaneous cross-linking at body temperature, with no further chemicals added, the fibres become insoluble and the excess PEO can be washed out. Albumin deposited along the fibres retains its native characteristics, such as its non-adhesiveness to cells and its susceptibility for degradation by macrophages. To demonstrate this we evaluated the mechanical properties, biocompatibility and biodegradability of this novel product. After subcutaneous implantation in mice, albumin mats were completely resorbable within six days and elicited only a limited local inflammatory response. In vitro, the mats suppressed cell attachment and migration. As this product is inexpensive, produced from human pharmaceutical grade albumin without chemical modifications, retains its native protein properties and fulfils the specific requirements for anti-adhesive dressings, its clinical use can be expedited. We believe that it could specifically be used when treating paediatric patients with epidermolysis bullosa, in whom non-healing wounds occur after minor hand injuries which lead to rapid adhesions and devastating contractures.


Subject(s)
Biocompatible Materials/pharmacology , Materials Testing/methods , Tissue Engineering , Albumins/ultrastructure , Animals , Circular Dichroism , Female , Fibroblasts/cytology , Fibroblasts/drug effects , Humans , Leukocytes/drug effects , Mice, Inbred BALB C , Microscopy, Atomic Force , Pilot Projects , Polyethylene Glycols/chemistry , Prosthesis Implantation , Solubility , Solutions
7.
J Biomater Sci Polym Ed ; 25(8): 802-25, 2014.
Article in English | MEDLINE | ID: mdl-24754323

ABSTRACT

The study was conducted to evaluate the cytocompatibility and hydrolytic degradability of the new poly(lactic acid)/polyethylene glycol-polyhedral oligomeric silsesquioxane (peg-POSS/PLLA) nanocomposite as potential material for cartilage regeneration. PLLA scaffolds containing 0 to 5% of peg-POSS were fabricated by electrospinning. Human mesenchymal stem cells (hMSC's) were cultured in vitro to evaluate the cytocompatibility of the new nanocomposite material. Hydrolytic degradation studies were also carried out to analyze the mass loss rate of the nanocomposites through time. The addition of the peg-POSS to the PLLA did not affect the processability of the nanocomposite by electrospinning. It was also observed that peg-POSS did not show any relevant change in fibers morphology, concluding that it was well dispersed. However, addition of peg-POSS caused noticeable decrease in mean fiber diameter, which made the specific surface area of the scaffold to rise. hMSC's were able to attach, to proliferate, and to differentiate into chondrocytes in a similar way onto the different types of electrospun peg-POSS/PLLA and pure PLLA scaffolds, showing that the peg-POSS as nano-additive does not exhibit any cytotoxicity. The hydrolytic degradation rate of the material was lower when peg-POSS was added, showing a higher durability of the nanocomposites through time. Results demonstrate that the addition of peg-POSS to the PLLA scaffolds does not affect its cytocompatibility to obtain hyaline cartilage from hMSC's.


Subject(s)
Biocompatible Materials/chemistry , Chondrogenesis/drug effects , Electricity , Lactic Acid/chemistry , Nanocomposites/chemistry , Organosilicon Compounds/chemistry , Polymers/chemistry , Regeneration/drug effects , Biocompatible Materials/pharmacology , Chondrocytes/cytology , Chondrocytes/drug effects , Humans , Hydrolysis , Mesenchymal Stem Cells/cytology , Mesenchymal Stem Cells/drug effects , Polyesters , Tissue Scaffolds/chemistry , Viscosity
8.
Eur J Surg Oncol ; 38(6): 490-6, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22381671

ABSTRACT

BACKGROUND: Metastatic gastric cancer remains a significant problem as the majority of Western patients are diagnosed with disseminated disease and no routine therapeutic regimen is accepted in such cases. METHODS: A cohort of 3141 patients with gastric cancer operated between 1990 and 2005 was evaluated using a multicenter data set held by the Polish Gastric Cancer Study Group to determine potential risks and benefits of non-curative gastrectomy for metastatic disease. Additionally, parameters of Quality of Life (QoL) were evaluated prospectively in 140 patients undergoing gastrectomy using the QLQ-C30 questionnaire. RESULTS: Gastrectomy was carried out in 2258 patients. Distant organ metastases were diagnosed in 951 patients, 415 of which underwent non-curative gastrectomy. The overall mortality rates were significantly higher in patients undergoing non-resectional surgery (10%) than either curative (3%, P < 0.001) or non-curative (4%, P = 0.002) gastrectomy. The overall median survival in patients with metastatic disease was significantly higher for non-curative gastrectomy (10.6 months, 95% confidence interval (CI) 9.3-11.9) than for non-resective operations (4.4 months, 95% CI 4.0 to 4.8, P < 0.001). The hazard ratio of death in patients subject to non-resectional surgery compared to those treated by gastrectomy was 2.923 (95% CI 2.473 to 3.454, P < 0.001). A gradual impairment in QoL parameters was found over 12 months after non-curative resections but changes did not reach statistical significance and individual parameters were similar to gastrectomy without distant metastases. CONCLUSION: Non-curative gastrectomy for metastatic gastric cancer is associated with significantly better survival compared to non-resective surgery and does not impair quality of life.


Subject(s)
Gastrectomy , Quality of Life , Stomach Neoplasms/pathology , Stomach Neoplasms/surgery , Adolescent , Adult , Aged , Aged, 80 and over , Constipation/etiology , Diarrhea/etiology , Female , Gastrectomy/adverse effects , Humans , Male , Medical Records , Middle Aged , Odds Ratio , Poland , Proportional Hazards Models , Prospective Studies , Retrospective Studies , Surveys and Questionnaires , Survival Analysis , Time Factors , Treatment Outcome
9.
Neuroscience ; 194: 220-6, 2011 Oct 27.
Article in English | MEDLINE | ID: mdl-21839809

ABSTRACT

A goal of our studies is to develop a potential therapeutic for Parkinson's disease (PD) by a human glial cell line-derived neurotrophic factor (hGDNF) expression plasmid administered to the rat striatum as a compacted DNA nanoparticle (DNP) and which will generate long-term hGDNF expression at biologically active levels. In the present study, we used a DNA plasmid encoding for hGDNF and a polyubiquitin C (UbC) promoter that was previously shown to have activity in both neurons and glia, but primarily in glia. A two-fold improvement was observed at the highest plasmid dose when using hGDNF DNA incorporating sequences found in RNA splice variant 1 compared with splice variant 2; of note, the splice variant 2 sequence is used in most preclinical studies. This optimized expression cassette design includes flanking scaffold matrix attachment elements (S/MARs) as well as a CpG-depleted prokaryotic domain and, where possible, eukaryotic elements. Stable long-term GDNF activity at levels 300-400% higher than baseline was observed following a single intracerebral injection. In a previous study, DNP plasmids encoding for reporter genes had been successful in generating long-term reporter transgene activity in the striatum (>365 days) and in this study produced sustained GDNF activity at the longest assessed time point (6 months).


Subject(s)
Brain Chemistry/genetics , Corpus Striatum/metabolism , DNA/administration & dosage , Genetic Therapy/methods , Glial Cell Line-Derived Neurotrophic Factor/genetics , Nanoparticles/administration & dosage , Animals , Disease Models, Animal , Drug Delivery Systems/methods , Gene Expression Regulation/genetics , Glial Cell Line-Derived Neurotrophic Factor/administration & dosage , Humans , Male , Microinjections/methods , Nanoparticles/therapeutic use , Parkinsonian Disorders/genetics , Parkinsonian Disorders/metabolism , Parkinsonian Disorders/therapy , Primary Cell Culture , Rats , Rats, Sprague-Dawley
10.
Gene Ther ; 13(13): 1048-51, 2006 Jul.
Article in English | MEDLINE | ID: mdl-16525478

ABSTRACT

Nanoparticles consisting of single molecules of DNA condensed with polyethylene glycol-substituted lysine 30-mers efficiently transfect lung epithelium following intrapulmonary administration. Nanoparticles formulated with lysine polymers having different counterions at the time of DNA mixing have distinct geometric shapes: trifluoroacetate or acetate counterions produce ellipsoids or rods, respectively. Based on intracytoplasmic microinjection studies, nanoparticle ellipsoids having a minimum diameter less than the 25 nm nuclear membrane pore efficiently transfect non-dividing cells. This 25 nm size restriction corresponds to a 5.8 kbp plasmid when compacted into spheroids, whereas the 8-11 nm diameter of rod-like particles is smaller than the nuclear pore diameter. In mice, up to 50% of lung cells are transfected after dosing with a rod-like compacted 6.9 kbp lacZ expression plasmid, and correction of the CFTR chloride channel was observed in humans following intranasal administration of a rod-like compacted 8.3 kbp plasmid. To further investigate the potential size and shape limitations of DNA nanoparticles for in vivo lung delivery, reporter gene activity of ellipsoidal and rod-like compacted luciferase plasmids ranging in size between 5.3 and 20.2 kbp was investigated. Equivalent molar reporter gene activities were observed for each formulation, indicating that microinjection size limitations do not apply to the in vivo gene transfer setting.


Subject(s)
Cystic Fibrosis/therapy , Genetic Therapy/methods , Lung/enzymology , Plasmids/genetics , Transfection/methods , Cell Line , Cystic Fibrosis/metabolism , Epithelial Cells/enzymology , Gene Expression , Green Fluorescent Proteins/analysis , Green Fluorescent Proteins/genetics , Humans , Luciferases/analysis , Luciferases/genetics , Microscopy, Electron, Transmission , Nanostructures , Nanotechnology
11.
Brain Res ; 901(1-2): 184-94, 2001 May 18.
Article in English | MEDLINE | ID: mdl-11368966

ABSTRACT

The effect of different temperatures of ACSF (18-42 degrees C) on carbachol (CCH)-induced field potentials were examined in the present study. Two hundred and thirty one experiments were performed on hippocampal formation slices maintained in a gas-liquid interface chamber. All slices were perfused with 50 microM CCH. A recording electrode was positioned in the region of CA3c pyramidal cells. The experiments gave two main findings. First, in a presence of continuous cholinergic stimulation the temperature of the bathing medium per se determined the rate of synchronization of the field potentials and pattern of EEG activity recorded. Second, within the temperature range from 33 degrees to 37 degrees C a window effect of temperature on CCH-induced theta-like activity (TLA) was noted: in this temperature range all slices tested responded only with one pattern of EEG activity-TLA. The results are discussed in light of temperature effects on hippocampal neuronal networks.


Subject(s)
Action Potentials/physiology , Body Temperature/physiology , Carbachol/pharmacology , Cholinergic Agonists/pharmacology , Hippocampus/physiology , Neurons/physiology , Theta Rhythm/drug effects , Action Potentials/drug effects , Animals , Epilepsy/chemically induced , Epilepsy/physiopathology , Hippocampus/drug effects , Male , Neurons/drug effects , Organ Culture Techniques , Rats , Rats, Wistar
12.
Curr Med Chem ; 8(1): 51-64, 2001 Jan.
Article in English | MEDLINE | ID: mdl-11172692

ABSTRACT

Multidrug resistance (MDR) in model systems is known to be conferred by two different integral proteins--the 170-kDa P-glycoprotein (P-gp) and the 190-kDa multidrug resistance-associated protein (MRP1)--that pump drugs out of MDR cells. The intracellular level of a drug, which influences the drug's cytotoxic effect, is a function of the amount of drug transported inside the cell (influx) and the amount of drug expelled from the cell (efflux). One possible pharmacological approach to overcoming drug resistance is the use of specific inhibitors that enhance the cytotoxicity of known antineoplastic agents. Many compounds have been proven to be very efficient in inhibiting P-gp activity, but only some of them can inhibit MRP1. However, the clinical results obtained so far by this approach have been rather disappointing. The other likely approach is based on the design and synthesis of new non-cross-resistant drugs whose physicochemical properties favor the uptake of such drug by resistant cells. Our recent studies have shown that whereas the P-gp- and MRP1-mediated efflux of different anthracycline-based drugs may not differ considerably, their kinetics of uptake do. Thus, the high uptake of drug by cells may lead to concentrations at the cellular target site high enough to achieve the needed cytotoxicity against MDR cells. Therefore, increased drug lipophilicity might be one factor in improving drug cytotoxicity in MDR cells. In vitro studies have shown that idarubicin, an analogue of daunorub cin, is more effective than daunorubicin and doxorubicin against MDR tumor cell lines and that this increased effectiveness is related in part to the increased lipophilicity of idarubicin. Other studies have also confirmed the strong impact of lipophilicity on the uptake and retention of anthracyclines in MDR cells.


Subject(s)
Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Drug Resistance, Multiple/genetics , Drug Resistance, Neoplasm/genetics , Neoplasms/drug therapy , Neoplasms/metabolism , Animals , Antibiotics, Antineoplastic/metabolism , Antibiotics, Antineoplastic/pharmacology , Biological Transport, Active/drug effects , Biological Transport, Active/genetics , Humans , Tumor Cells, Cultured
13.
Postepy Hig Med Dosw ; 54(3): 279-90, 2000.
Article in Polish | MEDLINE | ID: mdl-10941262

ABSTRACT

The present paper reviews the experimental data concerning the use of trans-slice preparation technique in investigation of theta-like activity generation in the limbic cortex. Specific aspects of the technical arrangement of the hippocampal formation and entorhinal cortex microelectroencephalographic registration were emphasized.


Subject(s)
Electroencephalography , Limbic System/physiology , Animals , Electroencephalography/instrumentation , Electroencephalography/methods , Entorhinal Cortex/physiology , Hippocampus/physiology , In Vitro Techniques , Microelectrodes , Theta Rhythm
14.
Acta Neurobiol Exp (Wars) ; 60(1): 67-85, 2000.
Article in English | MEDLINE | ID: mdl-10769932

ABSTRACT

The generation of EEG theta rhythm in the mammalian limbic cortex is a prime example of rhythmic activity that involves central mechanisms of oscillations and synchrony. This EEG pattern has been extensively studied since 1938, when Jüng and Kornmüller (1938) demonstrated the first theta recordings in the hippocampal formation of rabbits. In 1986 in collaboration with Drs. B.H. Bland, S.H. Roth and B.M. MacIver we demonstrated for the first time that bath perfusion of hippocampal slices with the cholinergic agonist, carbachol, resulted in theta-like oscillations. Since this initial demonstration of in vitro theta-like activity, we have carried out a number of experiments in an attempt to answer the basic question: what are the similarities between cholinergic-induced in vitro theta-like activity and theta rhythm which naturally occurs in the in vivo preparation. Thus far, our studies have provided strong evidence that theta-like activity recorded in vitro shares many of the physiological and pharmacological properties of theta rhythm observed in vivo. The question whether in vitro theta-like oscillations reflect features of epileptiform activity is also addressed in this review.


Subject(s)
Entorhinal Cortex/physiopathology , Epilepsy/physiopathology , Limbic System/physiopathology , Theta Rhythm , Animals , Cholinergic Fibers/physiology , Entorhinal Cortex/cytology , In Vitro Techniques , Limbic System/cytology
15.
Opt Lett ; 25(5): 332-4, 2000 Mar 01.
Article in English | MEDLINE | ID: mdl-18059871

ABSTRACT

The wavelength dependence of the one-photon absorption-induced photodegradation rate has been measured from the visible to the near IR for a variety of electro-optic chromophore-doped polymers. Systematic behavior is identified. The lifetime of the electro-optic activity is found to increase exponentially over 4-6 orders of magnitude for wavelengths ranging from peak of absorption, typically in the visible, to ~1000 nm. Many popular chromophores developed for electro-optics over the past 10 years are compared.

17.
Med Wieku Rozwoj ; 3(4): 471-84, 1999.
Article in Polish | MEDLINE | ID: mdl-10910672

ABSTRACT

Anti-tobacco education programmes for children and youth, developed at the National Research Institute of Mother and Child, are presented. The targets and goals of elaboration and implementation of these programmes are discussed. The four programmes contribute to a continuum of anti-tobacco education from preschool to secondary school. For each programme, the elaborated educational objectives, curriculum structure and methodology are presented. Problems related to evaluation of health promotion programmes are discussed in relation to the requirements of evidence-based medicine. Results of pilot programme implementation are presented. The programmes have been accepted by teachers, pupils and parents and can be implemented in the reformed education system in Poland.


Subject(s)
Health Education/organization & administration , Schools , Smoking Prevention , Adolescent , Child , Curriculum , Evidence-Based Medicine , Humans , Pilot Projects , Poland , Program Development , Program Evaluation
18.
Opt Lett ; 24(23): 1741-3, 1999 Dec 01.
Article in English | MEDLINE | ID: mdl-18079921

ABSTRACT

The photodegradation of the azobenzene chromophore DR1 {4-[N-ethyl-N-(2-hydroxyethyl)amino]-4(?)-nitroazobenzene]} incorporated as a side chain or as a guest in a poly(methyl) methacrylate host has been evaluated as a function of wavelength, temperature, and the atmospheric environment. The effects of these variables on the lifetime of DR1-based electro-optic devices is quantified.

19.
Obstet Gynecol ; 91(3): 396-400, 1998 Mar.
Article in English | MEDLINE | ID: mdl-9491867

ABSTRACT

OBJECTIVE: To investigate the association between a low unconjugated estriol (uE3) in the second trimester and adverse pregnancy outcomes. METHODS: Three hundred nine women who underwent second-trimester maternal serum alpha-fetoprotein (AFP)-hCG-uE3 screening were divided into two groups: those with uE3 at most 0.75 multiples of the median (MoM) (n = 81) and those with uE3 exceeding 0.75 MoM (n = 228). Entry criteria included: hCG below 2 MoM, AFP below 2 MoM, age less than 35 years at delivery, complete prenatal records, and completed delivery. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for a variety of adverse pregnancy outcomes. RESULTS: After adjusting for smoking and hCG, women with uE3 at or below 0.75 MoM were found to have significantly higher odds of developing fetal growth restriction, low amniotic fluid index (AFI), and small for gestational age (SGA) with ORs (and 95% CIs) of 6.73 (2.55, 17.74), 3.85 (1.53, 9.68), and 2.89 (1.27, 6.57), respectively, for each of the outcomes. CONCLUSION: Low uE3 in the second trimester appears to be associated with fetal growth restriction, low AFI, and SGA, and the risk seems to be independent of risk for adverse infant outcome associated with elevated AFP or hCG.


Subject(s)
Estriol/blood , Pregnancy Outcome , Adult , Biomarkers/blood , Female , Fetal Growth Retardation/etiology , Humans , Infant, Small for Gestational Age , Odds Ratio , Pregnancy , Pregnancy Trimester, Second
20.
Biochemistry ; 35(30): 9772-81, 1996 Jul 30.
Article in English | MEDLINE | ID: mdl-8703950

ABSTRACT

Polyphosphate glucokinase from Mycobacterium tuberculosis catalyzes the phosphorylation of glucose using inorganic polyphosphates [poly(P)] or ATP. The steady-state kinetic mechanisms of the poly(P)- and ATP-dependent glucokinase reactions were investigated using initial velocity, product inhibition, and dead-end inhibition analyses. In the poly(P)-dependent reaction, the enzyme follows an Ordered Bi Bi sequential mechanism with poly(P) binding to the enzyme first and glucose 6-phosphate dissociating last. Polyphosphate is utilized nonprocessively with a preference for longer chains due to higher kcat/K(m) values. The lack of inhibition at high poly(P) concentrations suggests that binding of poly(P) as a product is not favorable. In the ATP-dependent glucokinase reaction, the data are also consistent with an Ordered Bi Bi sequential mechanism, with ATP binding to the enzyme first and glucose 6-phosphate leaving last. At high concentrations, ATP displays competitive substrate inhibition with respect to glucose, which is consistent with the formation of an enzyme.ATP.ATP nonproductive complex. The overall catalytic efficiencies (kcat/KiaK(b)) of the poly(P)- and ATP-dependent reactions are approximately 10(11) M-2 s-1 and approximately 10(8) M-2 s-1, respectively. The higher catalytic efficiency, high value of the substrate specificity constant (kcat/K(a)) approaching a diffusion-controlled limit, and the absence of substrate inhibition in the poly(P)-dependent reaction suggest that poly(P), rather than ATP, is the major phosphate donor for poly(P)-glucokinase in M. tuberculosis.


Subject(s)
Mycobacterium tuberculosis/enzymology , Phosphotransferases/metabolism , Adenosine Triphosphate/metabolism , Enzyme Inhibitors/pharmacology , Kinetics , Mathematics , Models, Theoretical , Polyphosphates/metabolism , Substrate Specificity
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