Myeloperoxidase (MPO) catalyzes the formation of potent oxidants that have been implicated in pathogenesis various diseases including atherosclerosis, asthma, arthritis, and cancer. Melatonin plays an important part regulation body functions circadian sleep rhythms, blood pressure, oncogenesis, retinal function, seasonal reproduction, immunity. Here, we demonstrate melatonin serves as a inhibitor MPO under physiological-like conditions. In presence chloride (Cl-), inactivated at two points...

Black cumin (Nigella sativa L. [N.sativa]) seed extracts demonstrated numerous beneficial biological effects including, among others, antidiabetic, anticancer, immunomodulatory, antimicrobial, anti-inflammatory, antihypertensive, and antioxidant activity. To better understand the phytochemical composition of N. seeds, methanol were analyzed for phenolic acid flavonoid content. Furthermore, we tested methanol, n-hexane, aqueous their inhibitory activity against butyrylcholinesterase (BChE)...

Kinetic and structure analysis of inducible nitric oxide synthase (iNOS) revealed that, in addition to the increase iNOS expression inflamed areas, major pathway causing overproduction NO is destabilization iNOS–nitrosyl complex(es) that form during steady-state catalysis. Formation such a complex allows operate at only fraction (20–30%) its maximum activity. Thus, bioavailability scavengers sites inflammation may play an essential role up-regulation catalytic activity iNOS, by preventing...

Heavy metals, due to their inability degrade, pose a serious environmental and nutritional problem. The accumulation of essential non-essential heavy metals in living organisms reduces normal growth development, resulting acute poisoning, disease even death organisms. Melatonin is very important multifunctional molecule protecting plants from oxidative stress its ability directly neutralize reactive oxygen species (ROS). Also, melatonin has chelating property, which may contribute reducing...

We investigated the potential role of co-substrate, thiocyanate (SCN-), in modulating catalytic activity myeloperoxidase (MPO) and other members mammalian peroxidase superfamily (lactoperoxidase (LPO) eosinophil (EPO)). Pre-incubation SCN- with MPO generates a more complex biological setting, because serves as either substrate or inhibitor, causing diverse impacts on heme iron microenvironment. Consistent this hypothesis, relationship between association rate constant nitric oxide binding to...

We examined the potential physiological relevance of myeloperoxidase (MPO)−nitric oxide (NO) interactions as they may relate to cosubstrate, pseudo halide thiocyanate (SCN-), and substrate switching. Direct spectroscopic rapid kinetics studies revealed that SCN- interaction with MPO facilitates formation catalytic intermediate Compound II, limiting overall activity. However, a NO concentration (2 μM or less) dramatically influences build-up, duration, decay steady-state level II during...

Eosinophil peroxidase (EPO) catalyses the formation of oxidants implicated in pathogenesis various respiratory diseases including allergy and asthma. Mechanisms for inhibiting EPO, once released, are poorly understood. The aim this work is to determine mechanisms by which melatonin, a hormone produced brain pineal gland, inhibits catalytic activity EPO.

Abstract Introduction Endothelial dysfunction is involved in the pathogenesis of insulin resistance, diabetes mellitus type 2, diabetic complications and preceded clinical manifestation cardiovascular complications. Increased myeloperoxidase activity has been linked to a number pathologies with compelling evidence initiation progression inflammatory events. The aim this study was compare concentrations metabolite nitric oxide plasma 2 patients on metformin therapy, without signs disease...

Myeloperoxidase (MPO) structural analysis has suggested that halides and pseudohalides bind to the distal binding site serve as substrates or inhibitors, while others have concluded there are two separate sites. Here, evidence for distinct sites comes from bell-shaped effects observed when second-order rate constant of nitric oxide (NO) MPO was plotted versus Cl- concentration. The chloride level used in X-ray structure produced amino terminus helix halide insufficient populate either appear...

Recently research shows that horseradish peroxidase, HRP, when combined with other compounds, is highly reactive toward different human tumour cells and better understanding of catalytic mechanism inhibition HPR could lead to a new targeted cancer therapy. Thus, the HRP activity by dipotassium-trioxohydroxytetrafluorotriborate K 2 [B 3 O F 4 OH] was investigated for possible explanation previously observed antitumour activities this promising drug. studied under steady-state kinetic...

Heme reduction of ferric lactoperoxidase (LPO) into its ferrous form initially leads to the accumulation unstable LPO-Fe(II), which spontaneously converts a more stable species, two can be identified by Soret peaks at 440 and 434 nm, respectively. Our data demonstrate that both LPO-Fe(II) species are capable binding O2 similar rate generate ferrous-dioxy complex. Its formation with respect was first order monophasic constants kon = 3.8 × 104m–1 s–1 koff 11.2 s–1. The dissociation constant...

Heavy metals disturb the redox homeostasis of plant cell. The indolamine hormone, melatonin, protects plants from oxidative damage by directly scavenging reactive oxygen species or stimulating activity antioxidant enzymes. antioxidative role melatonin in leaves two medicinal plants, lemon balm (Melissa officinalis L.) and valerian (Valeriana that were treated with increased concentrations Zn Cd 24 h after sowing at an open field, investigated. Zn, Cd, a mixture mentioned metals. Exogenously...

The kinetic behavior of electron-transfer reactions involving several copper(II/I) complexes has previously been attributed to a dual-pathway "square scheme" mechanism in which changes the coordination geometry occur sequentially, rather than concertedly, with step. In case 14-membered macrocyclic quadridentate ligand studied date, major geometric change appears be inversion two coordinated donor atoms during overall process. However, relative importance these inversions matter speculation....

Eosinophil recruitment and enhanced nitric oxide (NO) production are characteristic features of asthma other airway diseases. peroxidase (EPO), a highly cationic hemoprotein secreted by activation eosinophils, is believed to play central role in host defense against invading pathogens. The enzyme uses hydrogen peroxide (H2O2) bromide (Br-), preferred cosubstrate EPO, generate the cytotoxic oxidant hypobromous acid. aim this work was determine whether NO can compete with plasma levels Br-...

Malignant neoplasms are today one of the leading causes death in world.Their treatment is extremely complex and requires application various chemical compounds which leads to disruption homeostasis human body.During a treatment, there possibility formation with important bioelements, such as copper, iron, cobalt, manganese, others biological system.This paper presents results possible complexes between Fe(II) Mn(II) ions capecitabine (IUPAC name: pentyl...