Low-activity Form Research Articles

Low-active forms of cellulosolitic microorganisms in archaeological contexts

This article presents the results of the study on low-active forms of cellulosolitic microorganisms in the soils of archaeological sites. The objects of the study were soils with traces of wooden structures in Vyatichi burials (12th century). To date, traces of wood are not visible at the macro level. The data obtained are compared with the results of a laboratory experiment to determine rates of cellulose decomposition in soils from various archaeological contexts. Cellulosolitic activity was determined by the application method. It has been shown that the cellulase activity of soils with traces of burial wooden structures is 20% of the level of modern soils. This suggests the awakening or presence of living, low-active microorganisms that have survived in the soil for 800 years.

Camptothecin: Solubility, In-Vitro Drug Release, and Effect on Human Red Blood Cells and Sperm Cold Preservation

BACKGROUND: Camptothecin (CPT) is an anticancer drug, and is not employed in the clinic because of its high hydrophobicity and low active form stability. CPT may also have potential for use in cold preservation. OBJECTIVE : To overcome these drawbacks, CPT solubility variations in the presence of cyclodextrins (CDs) and polyethylene glycol (PEG) were evaluated by Higuchi solubility experiments. MATERIALS AND METHODS: CPT was encapsulated in different cyclodextrins and polyethylene glycol using a co-evaporation method. The CPT interactions with CDs and PEG 6000 were investigated by Fourier-transformed infrared spectroscopy (FT-IR), and X-ray powder diffraction (XRPD). Then, CPT complexes were evaluated for in-vitro drug release. To evaluate the potential anticancer efficacy of the CPT complexes system, in-vitro cytotoxicity studies on human red blood cells were carried out using UV assay. The impact of the CPT complex systems on sperm motility protection during cold preservation at 4°C was studied using CASA. RESULTS: The dissolution profile of these preparations shows the improvement of the dissolution of the CPT following a fickien diffusion. The CPT solubility and stability improvement were the cause of the cytotoxicity on the red blood cells test. However, CPT alone, encapsulated, dispersed, and chemically modified protected spermatozoids during cold preservation. CONCLUSION: We confirm the interest in CPT encapsulated and dispersed in anticancer treatments. We also found that CPT encapsulated or dispersed could protect sperm against oxidative damage and improve the membrane integrity of human sperm. Consequently, CPT encapsulated our dispersed could eventually be beneficial for infertility therapy.

Selected Determinants of Health Behaviors of Primary School Teachers in the Kalisz County in Poland

Abstract Objectives The main goal of this paper is to assess the health behaviors of primary school teachers from the Kalisz county in the context of selected sociodemographic determinants. Material and methods The study was carried out between September and December 2021 among 500 primary school teachers in the Kalisz county in Poland. The selection of schools for the study was purposive sampling; 22 schools were randomly selected from primary schools in the Kalisz county. Ultimately, 315 correctly completed questionnaires were qualified for the study. The study employed the Authors’ Questionnaire Survey and the following standardized questionnaire: Inventory of Health-Related Behavior (IHB). Calculations were performed using STATISTICA 13.3 PL (TIBCO Software). Results The intensity of health behaviors was described as ‘average’ by 61.90% of the respondents. Based on the IHB questionnaire, it was found that the ‘preventive behaviors’ of the respondents had the strongest impact on their behavior and health. In the analyzed group, incorrect health behaviors (low physical activity or sedentary forms of leisure) prevailed. Conclusions The study discovered the prevalence of anti-health behaviors, which were dependent on sociodemographic factors. It is necessary to introduce corrective actions aimed at raising teachers’ health awareness and eliminating anti-health behaviors among this professional group.

The Two-Species Model of transketolase explains donor substrate-binding, inhibition and heat-activation

We recently characterised a low-activity form of E. coli transketolase, TKlow, which also binds the cofactor thiamine pyrophosphate (TPP) with an affinity up to two-orders of magnitude lower than the previously known high TPP-affinity and high-activity form, TKhigh, in the presence of Mg2+. We observed previously that partial oxidation was responsible for increased TKhigh activity, while low-activity TKlow was unmodified. In the present study, the fluorescence-based cofactor-binding assay was adapted to detect binding of the β-hydroxypyruvate (HPA) donor substrate to wild-type transketolase and a variant, S385Y/D469T/R520Q, that is active towards aromatic aldehydes. Transketolase HPA affinity again revealed the two distinct forms of transketolase at a TKhigh:TKlow ratio that matched those observed previously via TPP binding to each variant. The HPA dissociation constant of TKlow was comparable to the substrate-inhibition dissociation constant, KiHPA, determined previously. We provide evidence that KiHPA is a convolution of binding to the low-activity TKlow-TKlow dimer, and the TKlow subunit of the partially-active TKhigh-TKlow mixed dimer, where HPA binding to the TKlow subunit of the mixed dimer results in inhibition of the active TKhigh subunit. Heat-activation of transketolase was similarly investigated and found to convert the TKlow subunit of the mixed dimer to have TKhigh-like properties, but without oxidation.

Mechanism of Filamentation-Induced Allosteric Activation of the SgrAI Endonuclease

Filament formation by enzymes is increasingly recognized as an important phenomenon with potentially unique regulatory properties and biological roles. SgrAI is an allosterically regulated type II restriction endonuclease that forms filaments with enhanced DNA cleavage activity and altered sequence specificity. Here, we present the cryoelectron microscopy (cryo-EM) structure of the filament of SgrAI in its activated configuration. The structural data illuminate the mechanistic origin of hyperaccelerated DNA cleavage activity and suggests how indirect DNA sequence readout within filamentous SgrAI may enable recognition of substantially more nucleotide sequences than its low-activity form, thereby altering and partially relaxing its DNA sequence specificity. Together, substrate DNA binding, indirect readout, and filamentation simultaneously enhance SgrAI's catalytic activity and modulate substrate preference. This unusual enzyme mechanism may have evolved to perform the specialized functions of bacterial innate immunity in rapid defense against invading phage DNA without causing damage to the host DNA.

Synthesis of High Crystalline TiO2 Nanoparticles on a Polymer Membrane to Degrade Pollutants from Water

Titanium dioxide (TiO2) is described as an established material to remove pollutants from water. However, TiO2 is still not applied on a large scale due to issues concerning, for example, the form of use or low photocatalytic activity. We present an easily upscalable method to synthesize high active TiO2 nanoparticles on a polyethersulfone microfiltration membrane to remove pollutants in a continuous way. For this purpose, titanium(IV) isopropoxide was mixed with water and hydrochloric acid and treated up to 210 °C. After cooling, the membrane was simply dip-coated into the TiO2 nanoparticle dispersion. Standard characterization was undertaken (i.e., X-ray powder diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, water permeance, contact angle). Degradation of carbamazepine and methylene blue was executed. By increasing synthesis temperature crystallinity and photocatalytic activity elevates. Both ultrasound modification of nanoparticles and membrane pre-modification with carboxyl groups led to fine distribution of nanoparticles. The ultrasound-treated nanoparticles gave the highest photocatalytic activity in degrading carbamazepine and showed no decrease in degradation after nine times of repetition. The TiO2 nanoparticles were strongly bound to the membrane. Photocatalytic TiO2 nanoparticles with high activity were synthesized. The innovative method enables a fast and easy nanoparticle production, which could enable the use in large-scale water cleaning.

Global Kinetic Mechanism of Microsomal Glutathione Transferase 1 and Insights into Dynamic Enzyme Activation.

Microsomal glutathione transferase 1 (MGST1) has a unique ability to be activated, ≤30-fold, by modification with sulfhydryl reagents. MGST1 exhibits one-third-of-the-sites reactivity toward glutathione and hence heterogeneous binding to different active sites in the homotrimer. Limited turnover stopped-flow kinetic measurements of the activated enzyme allowed us to more accurately determine the KD for the "third" low-affinity GSH binding site (1.4 ± 0.3 mM). The rate of thiolate formation, k2 (0.77 ± 0.06 s-1), relevant to turnover, could also be determined. By deriving the steady-state rate equation for a random sequential mechanism for MGST1, we can predict KM, kcat, and kcat/KM values from these and previously determined pre-steady-state rate constants (all determined at 5 °C). To assess whether the pre-steady-state behavior can account for the steady-state kinetic behavior, we have determined experimental values for kinetic parameters at 5 °C. For reactive substrates and the activated enzyme, data for the microscopic steps account for the global mechanism of MGST1. For the unactivated enzyme and more reactive electrophilic substrates, pre-steady-state and steady-state data can be reconciled only if a more active subpopulation of MGST1 is assumed. We suggest that unactivated MGST1 can be partially activated in its unmodified form. The existence of an activated subpopulation (approximately 10%) could be demonstrated in limited turnover experiments. We therefore suggest that MSGT1 displays a preexisting dynamic equilibrium between high- and low-activity forms.

Discovery and structure-guided fragment-linking of 4-(2,3-dichlorobenzoyl)-1-methyl-pyrrole-2-carboxamide as a pyruvate kinase M2 activator

Tumor cells switch glucose metabolism to aerobic glycolysis by expressing the pyruvate kinase M2 isoform (PKM2) in a low active form, providing glycolytic intermediates as building blocks for biosynthetic processes, and thereby supporting cell proliferation. Activation of PKM2 should invert aerobic glycolysis to an oxidative metabolism and prevent cancer growth. Thus, PKM2 has gained attention as a promising cancer therapy target. To obtain novel PKM2 activators, we conducted a high-throughput screening (HTS). Among several hit compounds, a fragment-like hit compound with low potency but high ligand efficiency was identified. Two molecules of the hit compound bound at one activator binding site, and the molecules were linked based on the crystal structure. Since this linkage succeeded in maintaining the original position of the hit compound, the obtained compound exhibited highly improved potency in an in vitro assay. The linked compound also showed PKM2 activating activity in a cell based assay, and cellular growth inhibition of the A549 cancer cell line. Discovery of this novel scaffold and binding mode of the linked compound provides a valuable platform for the structure-guided design of PKM2 activators.

Systemic lupus erythematosus: an update.

Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disease predominantly affecting women of childbearing age. New classification criteria for SLE have greater sensitivity and therefore improve the diagnostic certainty for some patients, especially those who may previously have been labelled as having undifferentiated symptoms. Uncontrolled disease activity leads to irreversible end-organ damage, which in turn increases the risk of premature death; early and sustained control of disease activity can usually be achieved by conventional immunosuppressant therapy. The development of biological therapy lags behind that for other rheumatic diseases, with belimumab being the only targeted therapy approved by the Therapeutic Goods Administration. "Treat-to-target" concepts are changing trial design and clinical practice, with evidence-based definition of response criteria in the form of remission and low disease activity now on the horizon. While new therapies are awaited, research should also focus on optimising the use of current therapy and improving the quality of care of patients with SLE.

Effects of apoE variants on PLTP interaction and activation of low and high activity forms of PLTP

Effects of apoE variants on PLTP interaction and activation of low and high activity forms of PLTP

Protein evolution analysis of S-hydroxynitrile lyase by complete sequence design utilizing the INTMSAlign software.

Development of software and methods for design of complete sequences of functional proteins could contribute to studies of protein engineering and protein evolution. To this end, we developed the INTMSAlign software, and used it to design functional proteins and evaluate their usefulness. The software could assign both consensus and correlation residues of target proteins. We generated three protein sequences with S-selective hydroxynitrile lyase (S-HNL) activity, which we call designed S-HNLs; these proteins folded as efficiently as the native S-HNL. Sequence and biochemical analysis of the designed S-HNLs suggested that accumulation of neutral mutations occurs during the process of S-HNLs evolution from a low-activity form to a high-activity (native) form. Taken together, our results demonstrate that our software and the associated methods could be applied not only to design of complete sequences, but also to predictions of protein evolution, especially within families such as esterases and S-HNLs.

The criminal gene: the link between MAOA and aggression (REVIEW)

BackgroundOne emerging aspect of recent advances in neurocriminology is the discovery of possible links between violent criminal behaviour and genetics. Analysis of data from several studies indicates that the strongest link between genetic variation and aggression comes from monoamine oxidase A (MAOA); a gene encoding an enzyme responsible for catabolising amine neurotransmitters such as dopamine, serotonin and noradrenaline. In this work, we present a critical review of the data available from recent investigations regarding the impact of an allelic variation of the MAOA gene on criminal behaviour.METHODSThe main approach used in this work was reviewing and analysing data presented in a variety of research papers accessed through electronic search.RESULTSThe low activity form of the MAOA gene (MAOA-L) has been linked to increased levels of aggression and violence. Data from a 2007 study suggests that MAOA-L individuals are hypersensitive, so are affected more by negative experiences... Language: en

Phosphorylation and Prolyl Isomerization Independently Regulate the Signal Adapter Function of CrkII

The signaling protein CrkII switches between forms with high or low binding affinity. Both phosphorylation and native-state prolyl isomerization were suggested to regulate the transition between these forms. Here we analyzed how phosphorylation at Tyr222 and Tyr252 and the Pro238Ala substitution affect signal transfer of human and chicken CrkII to a downstream target. Human CrkII is regulated by phosphorylation only, but chicken CrkII is regulated by Pro238 trans→cis isomerization and by Tyr222 phosphorylation. Surprisingly, they act in an independent fashion. Apparently, the allosteric transition to a low-activity form can be induced by phosphorylation or prolyl isomerization located at distant sites in CrkII.

Oxidized extracellular DNA suppresses nitric oxide production by endothelial NO synthase (eNOS) in human endothelial cells (HUVEC).

Circulating DNA from patients with cardiovascular diseases reduce the synthesis of NO in endothelial cells, which is probably related to oxidative modification of DNA. To test this hypothesis, HUVEC cells were cultured in the presence of DNA containing ~1 (nonoxidized DNA), 700, or 2100 8-oxodG/10(6) nucleosides. Nonoxidized DNA stimulated the synthesis of NO, which was associated with an increase in the expression of endothelial NO synthase. Oxidized NO decreased the amount of mRNA and protein for endothelial NO synthase, but increased the relative content of its low active form. These changes were accompanied by reduction of NO production. These findings suggest that oxidative modification of circulating extracellular DNA contributes to endothelial dysfunction manifested in suppression of NO production.

MAOA and male antisocial behavior: A review

Of all the risk factors for the development of antisocial behavior, “maleness” is by far the most robust predictor. Among the numerous biological factors that have been identified as increasing risk for antisocial behavior, one of the most well-supported has inexplicably received very little attention with regard to implications for explaining why maleness is such a robust predictor. That factor is the low activity form of the monoamine oxidase-A gene. A major reason for this inattention to the MAOA-L gene appears to be the failure to appreciate that its location on the X chromosome reflects the enormous biological disadvantage of the male compared to the female. This article, after presenting a brief overview of the research which establishes that MAOA-L is one of the most well-supported biological risk factors for antisocial behaviors, explained how the enormous male biological disadvantage related to the sex difference in the prevalence of MAOA-L and thus helped explain why maleness is the most robust predictor of antisocial behavior. • Maleness is the most robust predictor of antisocial behavior. • The low activity form of the monoamine oxidase-A gene (MAOA-L) is the most well-supported link between a genetic variation and antisocial behavior. • Male are three times more likely than females to have the MAOA-L variation.

Genetic biomarkers of placebo response: what could it mean for future trial design?

Genetic biomarkers of placebo response: what could it mean for future trial design?

MAOA and Aggression

Political scientists tend to focus on environmental triggers as the primary precipitating cause for political violence. However, little has been done to explain why certain individuals faced with certain pressures resort to violence, while others confronting the same situation seek out diplomatic and peaceful resolutions to conflict. Here, using two independent samples, we explore the interaction between genetic disposition and violent early life events and their influence on engaging in physical violence. We find that individuals with the low-activity form of monoamine oxidase-A, who are exposed to violence in youth have a greater likelihood of engaging in physical aggression later in adulthood. Our findings hold important implications for the value of environmental intervention in communities besieged by political violence in order to reduce the likelihood of the intergenerational transfer of its propensity.

Serotonin in the Gut: What Does It Do?

Serotonin in the Gut: What Does It Do?

Chromia-alumina catalysts for the dehydrogenation of propane prepared by a modified method of codeposition

A method for preparing chromia-alumina catalysts for the dehydrogenation of propane, enabling us to increase the activity and thermal stability of a catalyst relative to currently known catalysts, is proposed. Chromia-alumina catalysts were prepared for the first time using a modified method of codeposition, in which a suspension of chromium and aluminum hydroxides was subjected to a high-temperature treatment (550°C). The proposed method is simple and allows us to reduce the number of stages in the preparation of the catalyst. The phase composition and texture of the catalyst, and the formation and properties of surface-active forms in dependence on the conditions of catalyst preparation, were studied using a set of physicochemical methods. The selected conditions of catalyst preparation ensured high specific surface area and a stable bond between the surface forms of chromium and the support, hindering the formation of the catalytically low-activity form α-Cr2O3 during calcination. In this work, we synthesized and studied laboratory samples of a chromia-alumina catalyst with different contents of chromium (2.8–11.3 wt %). With respect to the main parameters (conversion of propane, selectivity to propylene, and resistance to coke formation), the catalyst was as good as more active samples known from the literature and exhibited high activity at low chromium contents (2.8–5.5 wt %). This method of catalyst preparation is protected by a patent of the Russian Federation and recommended for improving industrial technology.

PET imaging of CXCR4 using copper-64 labeled peptide antagonist

Expression of CXCR4 in cancer has been found to correlate with poor prognosis and resistance to chemotherapy. In this study we developed a derivative of the CXCR4 peptide antagonist, T140-2D, that can be labeled easily with the PET isotope copper-64, and thereby enable in vivo visualization of CXCR4 in tumors. T140 was conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid mono (N-hydroxysuccinimide ester) (DOTA-NHS) to give T140-2D, which contains a DOTA molecule on each of the two lysine residues. (64)Cu-T140-2D was evaluated in vitro by migration and binding experiments, and in vivo by microPET imaging and biodistribution, in mice bearing CXCR4-positive and CXCR4-negative tumor xenografts. T140-2D was labeled with copper-64 to give (64)Cu-T140-2D in a high radiochemical yield of 86 ± 3% (not decay-corrected) and a specific activity of 0.28 - 0.30 mCi/µg (10.36 - 11.1 MBq/µg). (64)Cu-T140-2D had antagonistic and binding characteristics to CXCR4 that were similar to those of T140. In vivo, (64)Cu-T140-2D tended to bind to red blood cells and had to be used in a low specific activity form. In this new form (64)Cu-T140-2D enabled specific imaging of CXCR4-positive, but not CXCR4-negative tumors. Undesirably, however, (64)Cu-T140-2D also displayed high accumulation in the liver and kidneys. In conclusion, (64)Cu-T140-2D was easily labeled and, in its low activity form, enabled imaging of CXCR4 in tumors. It had high uptake, however, in metabolic organs. Further research with imaging tracers targeting CXCR4 is required.