Search results for "cysteine"
showing 10 items of 550 documents
Identification, Characterization and Synthesis of Natural Parasitic Cysteine Protease Inhibitors – More Potent Falcitidin Analogs
2021
ABSTRACTProtease inhibitors represent a promising therapeutic option for the treatment of parasitic diseases such as malaria and human African trypanosomiasis. Falcitidin was the first member of a new class of inhibitors of falcipain-2, a cysteine protease of the malaria parasite Plasmodium falciparum. Using a metabolomics dataset of 25 Chitinophaga strains for molecular networking enabled identification of over 30 natural analogs of falcitidin. Based on MS/MS spectra, they vary in their amino acid chain length, sequence, acyl residue, and C-terminal functionalization; therefore, they were grouped into the four falcitidin peptide families A-D. The isolation, characterization and absolute st…
Selenoproteins, cholesterol-lowering drugs, and the consequences: revisiting of the mevalonate pathway.
2004
3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) and peroxisome proliferator-activated receptor alpha activators (fibrates) are the backbone of pharmacologic hypercholesterolemia and dyslipidemia treatment. Many of their clinical effects, however, are still enigmatic. This article describes how a side road of the mevalonate pathway, characterized in recent years, can rationalize a major fraction of these unexplained observations. This side road is the enzymatic isopentenylation of selenocysteine-tRNA([Ser]Sec) (Sec-tRNA), the singular tRNA to decode the unusual amino acid selenocysteine. The functionally indispensable isopentenylation of Sec-tRNA requires a unique interm…
Identification of the membrane penetrating domain of Vibrio cholerae cytolysin as a β-barrel structure
2005
Summary Vibrio cholerae cytolysin (VCC) is an oligomerizing pore-forming toxin that is related to cytolysins of many other Gram-negative organisms. VCC contains six cysteine residues, of which two were found to be present in free sulphydryl form. The positions of two intramolecular disulphide bonds were mapped, and one was shown to be essential for correct folding of protoxin. Mutations were created in which the two free cysteines were deleted, so that single cysteine substitution mutants could be generated for site-specific labelling. Employment of polarity-sensitive fluorophores identified amino acid side-chains that formed part of the pore-forming domain of VCC. The sequence commenced at…
Insect Immunity
2001
Two novel antimicrobial peptides, which we propose to name termicin and spinigerin, have been isolated from the fungus-growing termite Pseudacanthotermes spiniger (heterometabole insect, Isoptera). Termicin is a 36-amino acid residue antifungal peptide, with six cysteines arranged in a disulfide array similar to that of insect defensins. In contrast to most insect defensins, termicin is C-terminally amidated. Spinigerin consists of 25 amino acids and is devoid of cysteines. It is active against bacteria and fungi. Termicin and spinigerin show no obvious sequence similarities with other peptides. Termicin is constitutively present in hemocyte granules and in salivary glands. The presence of …
Glutathione Peroxidase-1 and Homocysteine for Cardiovascular Risk Prediction
2005
Objectives This prospective study was designed to evaluate the effect of joint determination of two important contrary biomarkers—homocysteine and glutathione peroxidase (GPx)-1—on cardiovascular risk stratification. Background Homocysteine plasma levels have been associated with cardiovascular risk. Experimental data suggest that antioxidative GPx-1 activity modulates cardiovascular risk associated with homocysteine. Methods In 643 patients with coronary artery disease, we performed a prospective study to assess the risk of homocysteine plasma levels and GPx-1 activity on long-term cardiovascular risk with a median follow-up of 7.1 years. Results Both homocysteine and GPx-1 were among the …
Cathepsin L in Normal and Pathological Bone Remodeling
2011
Abstract Cathepsin L is a ubiquitous lysosomal cysteine endopeptidase that is mainly involved in the metabolic turnover of intracellular proteins. However, it is now well established that this enzyme may also be implicated in the regulation of other important biological processes includ- ing bone resorption. Therefore, altered expression levels of Cathepsin L may result in disturbances of bone homeo- stasis and, eventually, in the onset of pathological condi- tions associated with altered bone turnover. These observations support the concept that Cathepsin L may be regarded as an additional target for the development of novel therapeutic options for the treatment of patients with bone disea…
Altérations du métabolisme de l'homocystéine et maladies cardiovasculaires
1998
Resume L'homocysteine est un produit intermediaire du metabolisme de la methionine. L'augmentation moderee ou intermediaire de la concentration totale en homocysteine circulante, detectee dans les conditions basales ou apres le test de surcharge orale en methionine, est maintenant reconnue comme un facteur de risque important des maladies cardiovasculaires et des thromboses, chez les femmes comme chez les hommes, au meme titre que les facteurs de risques conventionnels. L'hyperhomocysteinemie, qui depend d'une inhibition de la voie de remethylation, d'une inhibition ou d'une saturation de la voie de transsulfuration, resulte d'une alteration de la regulation coordonnee du metabolisme de l'h…
HPLC Method for Cyst(e)ine and Methionine in Infant Formulas
1996
Cyst(e)ine and methionine were converted into cysteic acid and methionine sulfone by oxidizing with performic acid. The oxidized samples were then subjected to acid hydrolysis (6N HCl, 105-110°C/24 hr). After derivatization with phenylisothiocyanate, reverse phase HPLC separation was carried out at 48°C and with UV detection. Different gradients and pH values in the eluent were assayed to determine the best resolution. Analytical parameters, detection and quantification limits, linearity, precision and accuracy, were determined. The method was reliable and accurate for measuring cyst(e)ine and methionine in infant formulae.
Oxidative Stress and Cognitive Alterations Induced by Cancer Chemotherapy Drugs: A Scoping Review
2021
Cognitive impairment is one of the most deleterious effects of chemotherapy treatment in cancer patients, and this problem sometimes remains even after chemotherapy ends. Common classes of chemotherapy-based regimens such as anthracyclines, taxanes, and platinum derivatives can induce both oxidative stress in the blood and in the brain, and these effects can be reproduced in neuronal and glia cell cultures. In rodent models, both the acute and repeated administration of doxorubicin or adriamycin (anthracyclines) or cisplatin impairs cognitive functions, as shown by their diminished performance in different learning and memory behavioural tasks. Administration of compounds with strong antiox…
Safety of Dietary Guanidinoacetic Acid: A Villain of a Good Guy?
2021
Guanidinoacetic acid (GAA) is a natural amino acid derivative that is well-recognized for its central role in the biosynthesis of creatine, an essential compound involved in cellular energy metabolism. GAA (also known as glycocyamine or betacyamine) has been investigated as an energy-boosting dietary supplement in humans for more than 70 years. GAA is suggested to effectively increase low levels of tissue creatine and improve clinical features of cardiometabolic and neurological diseases, with GAA often outcompeting traditional bioenergetics agents in maintaining ATP status during stress. This perhaps happens due to a favorable delivery of GAA through specific membrane transporters (such as…