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Hieronim Jakubowski - One of the best experts on this subject based on the ideXlab platform.
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paraoxonase 1 q192r genotype and activity affect homocysteine Thiolactone levels in humans
The FASEB Journal, 2018Co-Authors: Joanna Perlakajan, Kamila Borowczyk, Rafal Glowacki, Ottar Nygard, Hieronim JakubowskiAbstract:Genetic or nutritional deficiencies in 1 carbon and homocysteine (Hcy) metabolism elevate Hcy-Thiolactone levels and are associated with cardiovascular and neurologic diseases. Hcy-Thiolactone caus...
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quantification of urinary s and n homocysteinylated protein and homocysteine Thiolactone in mice
Analytical Biochemistry, 2016Co-Authors: Hieronim JakubowskiAbstract:Abstract Homocysteine (Hcy) and its metabolites Hcy-Thiolactone, N -Hcy-protein, and S -Hcy-protein are implicated in vascular and neurological diseases. However, quantification of these metabolites remains challenging. Here I describe streamlined assays for these metabolites based on their conversion to Hcy-Thiolactone. Free Hcy-Thiolactone is extracted from the urine with chloroform/methanol. Total Hcy is converted to Hcy-Thiolactone in the presence of 1 N HCl. Major urinary protein (MUP)-bound S -linked Hcy is liberated from the protein by reduction with dithiothreitol and converted to Hcy-Thiolactone. Acid hydrolysis of MUP with 6 N HCl liberates N -linked Hcy as Hcy-Thiolactone, which is then extracted with chloroform/methanol. Ferritin is used as an N -Hcy-protein standard and an authentic Hcy-Thiolactone is used to monitor the efficiency of extraction. Hcy-Thiolactone (free, derived from total Hcy, or from MUP-bound N -linked or S -linked Hcy) is separated by a cation exchange high-performance liquid chromatography, post-column derivatized with o -phthaldialdehyde, and quantified by fluorescence. Using these assays with as little as 2–20 μL of urine I show that MUP carry N -linked and S -linked Hcy and that N -Hcy-MUP and S -Hcy-MUP and Hcy-Thiolactone are severely elevated in cystathionine β-synthase-deficient mice. These assays will facilitate examination of the role of protein-related Hcy metabolites in health and disease.
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homocysteine Thiolactone and n homocysteinylated protein induce pro atherogenic changes in gene expression in human vascular endothelial cells
Amino Acids, 2015Co-Authors: Dorota Gurda, Hieronim Jakubowski, Luiza Handschuh, Weronika KotkowiakAbstract:Genetic or nutritional deficiencies in homocysteine (Hcy) metabolism lead to hyperhomocysteinemia (HHcy) and cause endothelial dysfunction, a hallmark of atherosclerosis. In addition to Hcy, related metabolites accumulate in HHcy but their role in endothelial dysfunction is unknown. Here, we examine how Hcy-Thiolactone, N-Hcy-protein, and Hcy affect gene expression and molecular pathways in human umbilical vein endothelial cells. We used microarray technology, real-time quantitative polymerase chain reaction, and bioinformatic analysis with PANTHER, DAVID, and Ingenuity Pathway Analysis (IPA) resources. We identified 47, 113, and 30 mRNAs regulated by N-Hcy-protein, Hcy-Thiolactone, and Hcy, respectively, and found that each metabolite induced a unique pattern of gene expression. Top molecular pathways affected by Hcy-Thiolactone were chromatin organization, one-carbon metabolism, and lipid-related processes [−log(P value) = 20–31]. Top pathways affected by N-Hcy-protein and Hcy were blood coagulation, sulfur amino acid metabolism, and lipid metabolism [−log(P value)] = 4–11; also affected by Hcy-Thiolactone, [−log(P value) = 8–14]. Top disease related to Hcy-Thiolactone, N-Hcy-protein, and Hcy was ‘atherosclerosis, coronary heart disease’ [−log(P value) = 9–16]. Top-scored biological networks affected by Hcy-Thiolactone (score = 34–40) were cardiovascular disease and function; those affected by N-Hcy-protein (score = 24–35) were ‘small molecule biochemistry, neurological disease,’ and ‘cardiovascular system development and function’; and those affected by Hcy (score = 25–37) were ‘amino acid metabolism, lipid metabolism,’ ‘cellular movement, and cardiovascular and nervous system development and function.’ These results indicate that each Hcy metabolite uniquely modulates gene expression in pathways important for vascular homeostasis and identify new genes and pathways that are linked to HHcy-induced endothelial dysfunction and vascular disease.
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metabolism and neurotoxicity of homocysteine Thiolactone in mice protective role of bleomycin hydrolase
Amino Acids, 2012Co-Authors: Hieronim Jakubowski, Kamila Borowczyk, Joanna TisonczykAbstract:Genetic or nutritional disorders in homocysteine (Hcy) metabolism elevate Hcy-Thiolactone and cause heart and brain diseases. Hcy-Thiolactone has been implicated in these diseases because it has the ability to modify protein lysine residues and generate toxic N-Hcy-proteins with auto-immunogenic, pro-thrombotic, and amyloidogenic properties. Bleomycin hydrolase (Blmh) has the ability to hydrolyze l-Hcy-Thiolactone (but not d-Hcy-Thiolactone) to Hcy in vitro, but whether this reflects a physiological function has been unknown. Here, we show that Blmh−/− mice excreted in urine 1.8-fold more Hcy-Thiolactone than wild-type Blmh+/+ animals (P = 0.02). Hcy-Thiolactone was elevated 2.3-fold in brains (P = 0.004) and 2.0-fold in kidneys (P = 0.047) of Blmh−/− mice relative to Blmh+/+ animals. Plasma N-Hcy-protein was elevated in Blmh−/− mice fed a normal (2.3-fold, P < 0.001) or hyperhomocysteinemic diet (1.5-fold, P < 0.001), compared with Blmh+/+ animals. More intraperitoneally injected l-Hcy-Thiolactone was recovered in plasma in Blmh−/− mice than in wild-type Blmh+/+ animals (83.1 vs. 39.3 μM, P < 0.0001). In Blmh+/+ mice injected intraperitoneally with d-Hcy-Thiolactone, d,l-Hcy-Thiolactone, or l-Hcy-Thiolactone, 88, 47, or 6.3%, respectively, of the injected dose was recovered in plasma. The incidence of seizures induced by l-Hcy-Thiolactone injections (3,700 nmol/g body weight) was higher in Blmh−/− than in Blmh+/+ mice (93.8 vs. 29.5%, P < 0.001). Using the Blmh null mice, we provide the first direct evidence that a specific Hcy metabolite, Hcy-Thiolactone, rather than Hcy itself, is neurotoxic in vivo. Taken together, our findings indicate that Blmh protects mice against l-Hcy-Thiolactone toxicity by metabolizing it to Hcy and suggest a mechanism by which Blmh might protect against neurodegeneration associated with hyperhomocysteinemia and Alzheimer’s disease.
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metabolism and neurotoxicity of homocysteine Thiolactone in mice evidence for a protective role of paraoxonase 1
Journal of Alzheimer's Disease, 2012Co-Authors: Kamila Borowczyk, Diana M Shih, Hieronim JakubowskiAbstract:Homocysteine (Hcy)-Thiolactone is toxic, induces epileptic seizures in rodents, and has been implicated in Alzheimer’s disease. Paraoxonase 1 (Pon1), a component of high-density lipoprotein, hydrolyzes Hcy-Thiolactone in vitro. Whether this reflects a physiological function and whether Pon1 can protect against Hcy-Thiolactone toxicity was unknown. Here we show that Hcy-Thiolactone was elevated in brains of Pon1−/− mice (1.5-fold, p = 0.047) and that Pon1−/− mice excrete more Hcy-Thiolactone than wild type animals (2.4-fold, p = 0.047). The frequency of seizures induced by intraperitoneal injections of L-Hcy-Thiolactone was significantly higher in Pon1−/− mice compared with wild type animals (52.8% versus 29.5%, p = 0.042); the latency of seizures was lower in Pon1−/− mice than in wild type animals (31.8 min versus 41.2 min, p = 0.019). Using the Pon1 null mice, we provide the first direct evidence that a specific Hcy metabolite, Hcy-Thiolactone, rather than Hcy itself is neurotoxic in vivo. Our findings indicate that Pon1 protects mice against Hcy-Thiolactone neurotoxicity by hydrolyzing it in the brain, and suggest a mechanism by which Pon1 can protect against neurodegeneration associated with hyperhomocysteinemia and Alzheimer’s disease.
Filip Du Prez - One of the best experts on this subject based on the ideXlab platform.
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a Thiolactone strategy for straightforward synthesis of disulfide linked side chain to tail cyclic peptides featuring an n terminal modification handle
ChemBioChem, 2018Co-Authors: Dorien Van Lysebetten, Pieter Espeel, Filip Du Prez, Stefania Felissati, Eirini Antonatou, Lieselot L G Carrette, Evelien Focquet, Annemieke MadderAbstract:The development of straightforward and versatile peptide cyclisation methods is highly desired to meet the demand for more stable peptide-based drugs. Herein, a new method for the synthesis of side-chain-to-tail cyclic peptides with the simultaneous introduction of an N-terminal handle, based on the introduction of an N-terminal Thiolactone building block, is described. A primary amine liberates a homocysteine analogue from the Thiolactone building block, which further enables cyclisation of the peptide through disulfide-bond formation with a C-terminal cysteamine. Postcyclisation modification can be achieved by using small bifunctional amines. Alternatively, the synthesis of lipopeptides is demonstrated through direct Thiolactone opening with long-chain alkyl amines.
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structurally diverse polymers from norbornene and Thiolactone containing building blocks
European Polymer Journal, 2018Co-Authors: Daniel Frank, Pieter Espeel, Nezha Badi, Filip Du PrezAbstract:Abstract A wide set of norbornene-derived polymers with a diversity in backbone and side chain structures has been prepared based on norbornene building blocks that also include a Thiolactone group. For this purpose, two Thiolactone monomers with differently substituted norbornene moieties were synthesized and their reactivity compared using three different polymerization strategies. First, their potential for amine-thiol-ene polymerization was evaluated using different amines, solvents and initiator concentrations in order to screen their influence on the molecular weight and glass transition temperature. Free radical (co-)polymerization and ring-opening metathesis polymerization were also applied and the obtained polymers were submitted to post-polymerization modification. The results showed that only the monomer 5-norbornenemethyl Thiolactone carbamate results in polymer formation under the tested conditions. The obtained compounds were characterized by SEC, TGA, DSC and NMR.
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multifunctional dendrimer formation using Thiolactone chemistry
Macromolecular Chemistry and Physics, 2017Co-Authors: Filip Du Prez, Ugur N Kaya, Nezha BadiAbstract:Thiolactone chemistry is a powerful tool for the design of complex multifunctional architectures. In this study, this versatile click-inspired synthetic strategy is conducted to prepare multifunctional dendrimer-like structures. For this purpose, a Thiolactone bearing an isocyanate function, prepared in multigram scale, is utilized for multiple step functionalization starting from a 4-arm star-shaped poly(ethylene glycol). Amine-thiol-acrylate conjugation is carried out in order to form the aforementioned structures. The efficient aminolysis of the Thiolactone ring and the reaction of the generated thiol with the double bond of an acrylate derivative are completed in a one-pot procedure. The choice of the amine and/or acrylate derivatives can allow the introduction of different functional groups for each new generation, potentially leading to multivalent dendrimer-like structures.
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uv cured multifunctional coating resins prepared from renewable Thiolactone derivatives
Progress in Organic Coatings, 2017Co-Authors: Cristina Resetco, Tamara Dikic, Tom Verbrugge, Filip Du PrezAbstract:Abstract A set of multifunctional UV-cured thiol-ene polymer resins were systematically prepared from Thiolactone containing monomers and different amine compounds. Aminolysis of the Thiolactone moiety enabled the introduction of different side chains and cross-linkers into the polymers. The glass transition temperature of the polymers varied between 22 and 90 °C, depending on the type and molar ratio of amine-containing compounds relative to the monomer. The properties of the UV-cured thin films were screened using standard tests for coatings, including pencil hardness, impact resistance, and cross-hatch adhesion. Thiolactone-derived polymer films exhibited high transparency of 90%, pencil hardness in the range of 3B-HB, high impact resistance >2 kg m, and good adhesion to steel in dry conditions.
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responsive Thiolactone derived n substituted poly urethane amide s
Macromolecular Rapid Communications, 2017Co-Authors: Pieter Espeel, Sensu Celasun, Pinar Sinem Omurtag, Steven Martens, Filip Du PrezAbstract:: AB' type monomers containing a Thiolactone unit and vinyl ether moiety have been prepared with high yields. Aminolysis of the Thiolactone moiety generates the corresponding thiol in situ, and upon UV-irradiation, radical polyaddition occurs in the same medium, yielding linear poly(amide-urethane)s with different side chain residues and (Poly(Ethylene Oxide)) PEO-like backbone. Moreover, these unique polymers feature lower critical solution temperature behavior in water. Systematic modification of the responsive polymers reveals the influence of the variation of the side chains and the backbone structure on the corresponding solubility properties. In selected cases, multiresponsive polymers have been developed, which also respond to pH and metal concentration.
Pieter Espeel - One of the best experts on this subject based on the ideXlab platform.
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a Thiolactone strategy for straightforward synthesis of disulfide linked side chain to tail cyclic peptides featuring an n terminal modification handle
ChemBioChem, 2018Co-Authors: Dorien Van Lysebetten, Pieter Espeel, Filip Du Prez, Stefania Felissati, Eirini Antonatou, Lieselot L G Carrette, Evelien Focquet, Annemieke MadderAbstract:The development of straightforward and versatile peptide cyclisation methods is highly desired to meet the demand for more stable peptide-based drugs. Herein, a new method for the synthesis of side-chain-to-tail cyclic peptides with the simultaneous introduction of an N-terminal handle, based on the introduction of an N-terminal Thiolactone building block, is described. A primary amine liberates a homocysteine analogue from the Thiolactone building block, which further enables cyclisation of the peptide through disulfide-bond formation with a C-terminal cysteamine. Postcyclisation modification can be achieved by using small bifunctional amines. Alternatively, the synthesis of lipopeptides is demonstrated through direct Thiolactone opening with long-chain alkyl amines.
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structurally diverse polymers from norbornene and Thiolactone containing building blocks
European Polymer Journal, 2018Co-Authors: Daniel Frank, Pieter Espeel, Nezha Badi, Filip Du PrezAbstract:Abstract A wide set of norbornene-derived polymers with a diversity in backbone and side chain structures has been prepared based on norbornene building blocks that also include a Thiolactone group. For this purpose, two Thiolactone monomers with differently substituted norbornene moieties were synthesized and their reactivity compared using three different polymerization strategies. First, their potential for amine-thiol-ene polymerization was evaluated using different amines, solvents and initiator concentrations in order to screen their influence on the molecular weight and glass transition temperature. Free radical (co-)polymerization and ring-opening metathesis polymerization were also applied and the obtained polymers were submitted to post-polymerization modification. The results showed that only the monomer 5-norbornenemethyl Thiolactone carbamate results in polymer formation under the tested conditions. The obtained compounds were characterized by SEC, TGA, DSC and NMR.
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responsive Thiolactone derived n substituted poly urethane amide s
Macromolecular Rapid Communications, 2017Co-Authors: Pieter Espeel, Sensu Celasun, Pinar Sinem Omurtag, Steven Martens, Filip Du PrezAbstract:: AB' type monomers containing a Thiolactone unit and vinyl ether moiety have been prepared with high yields. Aminolysis of the Thiolactone moiety generates the corresponding thiol in situ, and upon UV-irradiation, radical polyaddition occurs in the same medium, yielding linear poly(amide-urethane)s with different side chain residues and (Poly(Ethylene Oxide)) PEO-like backbone. Moreover, these unique polymers feature lower critical solution temperature behavior in water. Systematic modification of the responsive polymers reveals the influence of the variation of the side chains and the backbone structure on the corresponding solubility properties. In selected cases, multiresponsive polymers have been developed, which also respond to pH and metal concentration.
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double modification of polymer end groups through Thiolactone chemistry
Macromolecular Rapid Communications, 2016Co-Authors: Frank Driessen, Filip Du Prez, Steven Martens, Bernhard De Meyer, Pieter EspeelAbstract:A straightforward synthetic procedure for the double modification and polymer-polymer conjugation of telechelic polymers is performed through amine-thiol-ene conjugation. Thiolactone end-functionalized polymers are prepared via two different methods, through controlled radical polymerization of a Thiolactone-containing initiator, or by modification of available end-functionalized polymers. Next, these different linear polymers are treated with a variety of amine/acrylate-combinations in a one-pot procedure, creating a library of tailored end-functionalized polymers. End group conversions are monitored via SEC, NMR, and MALDI-TOF analysis, confirming the quantitative modification after each step. Finally, this strategy is applied for the synthesis of block copolymers via polymer-polymer conjugation and the successful outcome is analyzed via LCxSEC measurements.
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Thiolactone chemistry and copper mediated crp for the development of well defined amphiphilic dispersing agents
Polymer Chemistry, 2016Co-Authors: Frank Driessen, Pieter Espeel, Roald Herckens, Filip Du PrezAbstract:A straightforward synthetic pathway was developed for the synthesis of amphiphilic graft and toothbrush copolymers by combining copper-mediated controlled radical polymerization with the Thiolactone-based amine–thiol–ene conjugation in a “grafting-onto approach”. First, a series of well-defined, Thiolactone containing macromolecular backbones were synthesized via copolymerization with a Thiolactone-containing monomer. Next, acrylate end-functionalized polymers were obtained in a post-polymerization modification procedure and coupled to the backbones. Furthermore, in-depth characterization of the different structures was performed by the use of SEC, NMR, MALDI-TOF and LCxSEC analysis. In order to demonstrate the amphiphilic behaviour of these graft and toothbrush copolymers, micelle formation tests were carried out and measured with DLS and TEM, while the dispersing features of these comb-like copolymers were evaluated by pigment stabilization tests.
Nagy A Farid - One of the best experts on this subject based on the ideXlab platform.
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metabolism and disposition of the thienopyridine antiplatelet drugs ticlopidine clopidogrel and prasugrel in humans
The Journal of Clinical Pharmacology, 2010Co-Authors: Nagy A Farid, Atsushi Kurihara, Steven A WrightonAbstract:Ticlopidine, clopidogrel, and prasugrel are thienopyridine prodrugs that inhibit adenosine-5'-diphosphate (ADP)― mediated platelet aggregation in vivo. These compounds are converted to thiol-containing active metabolites through a corresponding Thiolactone. The 3 compounds differ in their metabolic pathways to their active metabolites in humans. Whereas ticlopidine and clopidogrel are metabolized to their Thiolactones in the liver by cytochromes P450, prasugrel proceeds to its Thiolactone following hydrolysis by carboxylesterase 2 during absorption, and a portion of prasugrel's active metabolite is also formed by intestinal CYP3A. Both ticlopidine and clopidogrel are subject to major competing metabolic pathways to inactive metabolites. Thus, varying efficiencies in the formation of active metabolites affect observed effects on the onset of action and extent of inhibition of platelet aggregation (IPA). Knowledge of the CYP-dependent formation of ticlopidine and clopidogrel Thiolactones helps explain some of the observed drug-drug interactions with these molecules and, more important, the role of CYP2C19 genetic polymorphism on the pharmacokinetics of and pharmacodynamic response to clopidogrel. The lack of drug interaction potential and the absence of CYP2C19 genetic effect result in a predictable response to thienopyridine antiplatelet therapy with prasugrel. Current literature shows that greater ADP-mediated IPA is associated with significantly better clinical outcomes for patients with acute coronary syndrome.
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a possible mechanism for the differences in efficiency and variability of active metabolite formation from thienopyridine antiplatelet agents prasugrel and clopidogrel
Drug Metabolism and Disposition, 2009Co-Authors: Katsunobu Hagihara, Miho Kazui, Atsushi Kurihara, Osamu Okazaki, Nagy A Farid, Michiharu Yoshiike, Kokichi Honda, Toshihiko IkedaAbstract:The efficiency and interindividual variability in bioactivation of prasugrel and clopidogrel were quantitatively compared and the mechanisms involved were elucidated using 20 individual human liver microsomes. Prasugrel and clopidogrel are converted to their thiol-containing active metabolites through corresponding Thiolactone metabolites. The formation rate of clopidogrel active metabolite was much lower and more variable [0.164 ± 0.196 μl/min/mg protein, coefficient of variation (CV) = 120%] compared with the formation of prasugrel active metabolite (8.68 ± 6.64 μl/min/mg protein, CV = 76%). This result was most likely attributable to the less efficient and less consistent formation of clopidogrel Thiolactone metabolite (2.24 ± 1.00 μl/min/mg protein, CV = 45%) compared with the formation of prasugrel Thiolactone metabolite (55.2 ± 15.4 μl/min/mg protein, CV = 28%). These differences may be attributed to the following factors. Clopidogrel was largely hydrolyzed to an inactive acid metabolite (approximately 90% of total metabolites analyzed), and the clopidogrel concentrations consumed were correlated to human carboxylesterase 1 activity in each source of liver microsomes. In addition, 48% of the clopidogrel Thiolactone metabolite formed was converted to an inactive Thiolactone acid metabolite. The oxidation of clopidogrel to its Thiolactone metabolite correlated with variable activities of CYP1A2, CYP2B6, and CYP2C19. In conclusion, the active metabolite of clopidogrel was formed with less efficiency and higher variability than that of prasugrel. This difference in Thiolactone formation was attributed to hydrolysis of clopidogrel and its Thiolactone metabolite to inactive acid metabolites and to variability in cytochrome P450-mediated oxidation of clopidogrel to its Thiolactone metabolite, which may contribute to the poorer and more variable active metabolite formation for clopidogrel than prasugrel.
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mechanism based inhibition of human cytochrome p450 2b6 by ticlopidine clopidogrel and the Thiolactone metabolite of prasugrel
Drug Metabolism and Disposition, 2009Co-Authors: Yumi Nishiya, Katsunobu Hagihara, Atsushi Kurihara, Nagy A Farid, Masami Tajima, Shinichi Miura, Toshihiko IkedaAbstract:Mechanism-based inhibition of CYP2B6 in human liver microsomes by thienopyridine antiplatelet agents ticlopidine and clopidogrel and the Thiolactone metabolites of those two agents plus that of prasugrel were investigated by determining the time- and concentration-dependent inhibition of the activity of bupropion hydroxylase as the typical CYP2B6 activity. By comparing the ratios of k inact (maximal inactivation rate constant)/ K I (the inactivator concentration producing a half-maximal rate of inactivation), it was found that the Thiolactone metabolite of prasugrel is 10- and 22-fold less potent, respectively, in the mechanism-based inhibition of CYP2B6 than ticlopidine and clopidogrel. The k inact / K I ratio of the Thiolactone metabolite of ticlopidine was comparable with that of the parent compound, whereas this ratio for the Thiolactone metabolite of clopidogrel was significantly smaller than that of clopidogrel. In conclusion, ticlopidine, its Thiolactone metabolite, and clopidogrel were more potent mechanism-based inhibitors of CYP2B6 than the Thiolactone metabolite of prasugrel.
Rafal Glowacki - One of the best experts on this subject based on the ideXlab platform.
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urinary excretion of homocysteine Thiolactone and the risk of acute myocardial infarction in coronary artery disease patients the wenbit trial
Journal of Internal Medicine, 2019Co-Authors: Kamila Borowczyk, Rafal Glowacki, Ottar Nygard, Justyna Piechocka, Indu Dhar, Oivind Midtun, Grethe S Tell, Per Magne UelandAbstract:Objectives No individual homocysteine (Hcy) metabolite has been studied as a risk marker for coronary artery disease (CAD). Our objective was to examine Hcy-Thiolactone, a chemically reactive metabolite generated by methionyl-tRNA synthetase and cleared by the kidney, as a risk predictor of incident acute myocardial infarction (AMI) in the Western Norway B-Vitamin Intervention Trial. Design Single centre, prospective double-blind clinical intervention study, randomized in a 2 × 2 factorial design. Subjects and methods Patients with suspected CAD (n = 2049, 69.8% men; 61.2-year-old) were randomized to groups receiving daily (i) folic acid (0.8 mg)/vitamin B12 (0.4 mg)/vitamin B6 (40 mg); (ii) folic acid/vitamin B12 ; (iii) vitamin B6 or (iv) placebo. Urinary Hcy-Thiolactone was quantified at baseline, 12 and 38 months. Results Baseline urinary Hcy-Thiolactone/creatinine was significantly associated with plasma tHcy, ApoA1, glomerular filtration rate, potassium and pyridoxal 5'-phosphate (positively) and with age, hypertension, smoking, urinary creatinine, plasma bilirubin and kynurenine (negatively). During median 4.7-years, 183 patients (8.9%) suffered an AMI. In Cox regression analysis, Hcy-Thiolactone/creatinine was associated with AMI risk (hazard ratio = 1.58, 95% confidence interval = 1.10-2.26, P = 0.012 for trend; adjusted for age, gender, tHcy). This association was confined to patients with pyridoxic acid below median (adjusted HR = 2.72, 95% CI = 1.47-5.03, P = 0.0001; Pinteraction = 0.020). B-vitamin/folate treatments did not affect Hcy-Thiolactone/creatinine and its AMI risk association. Conclusions Hcy-Thiolactone/creatinine ratio is a novel AMI risk predictor in patients with suspected CAD, independent of traditional risk factors and tHcy, but modified by vitamin B6 catabolism. These findings lend a support to the hypothesis that Hcy-Thiolactone is mechanistically involved in cardiovascular disease.
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paraoxonase 1 q192r genotype and activity affect homocysteine Thiolactone levels in humans
The FASEB Journal, 2018Co-Authors: Joanna Perlakajan, Kamila Borowczyk, Rafal Glowacki, Ottar Nygard, Hieronim JakubowskiAbstract:Genetic or nutritional deficiencies in 1 carbon and homocysteine (Hcy) metabolism elevate Hcy-Thiolactone levels and are associated with cardiovascular and neurologic diseases. Hcy-Thiolactone caus...
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determination of homocysteine Thiolactone in urine by field amplified sample injection and sweeping mekc method with uv detection
Journal of Chromatography B, 2014Co-Authors: Paulina Furmaniak, Pawel Kubalczyk, Rafal GlowackiAbstract:Abstract Homocysteine Thiolactone (Hcy-Thiolactone), an intramolecular thioester, easily acylates free-amino groups in proteins, which impairs or alters the protein's biological function. Here, we describe new capillary electrophoresis assay for the determination of Hcy-Thiolactone in human urine based on a field amplified sample injection and sweeping MEKC with UV detection. The two steps procedure relies on sample liquid–liquid extraction followed by CE separation and UV detection at 240 nm. The Hcy-Thiolactone standard added to the urine before the extraction step shows that the response of the detector is linear within the range studied, from 0.1 to 1 μmol L −1 urine. The intra- and interday precision and recovery were 3.2–14.4% (average 5.1% and 9.3%) and 92.5–112.6% (average 99.8% and 99.1%), respectively. The lower limit of quantification was 0.09 nmol Hcy-Thiolactone in 1 mL of urine. The proposed method was applied for the analysis of 15 urine samples donated by apparently healthy volunteers. The average concentration of the analyte was 0.170 ± 0.029 μmol L −1 .
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an on column derivatization method for the determination of homocysteine Thiolactone and protein n linked homocysteine
Amino Acids, 2011Co-Authors: Rafal Glowacki, Hieronim Jakubowski, Edward BaldAbstract:Homocysteine (Hcy) is incorporated into protein via a reaction of the thioester Hcy-Thiolactone with e-amino group of a protein lysine residue generating N-Hcy-protein. This reaction impairs and alters protein’s function and has been implicated in atherothrombotic disease. Here, we describe new high-performance liquid chromatography assays for the determination of Hcy-Thiolactone, protein N-linked Hcy, and Hcy based on an on-column derivatization with o-phthaldialdehyde and fluorescence detection. The on-column derivatization generates narrow peaks, which allows fast run times (3–5 min) and facilitates determination of N-linked Hcy directly from acid hydrolysates of plasma protein. Utility of these assays was demonstrated with human urine and plasma samples.
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chemical biology of homocysteine Thiolactone and related metabolites
Advances in Clinical Chemistry, 2011Co-Authors: Hieronim Jakubowski, Rafal GlowackiAbstract:: Protein-related homocysteine (Hcy) metabolism produces Hcy-Thiolactone, N-Hcy-protein, and N epsilon-homocysteinyl-lysine (N epsilon-Hcy-Lys). Hcy-Thiolactone is generated in an error-editing reaction in protein biosynthesis when Hcy is erroneously selected in place of methionine by methionyl-tRNA synthetase. Hcy-Thiolactone, an intramolecular thioester, is chemically reactive and forms isopeptide bonds with protein lysine residues in a process called N-homocysteinylation, which impairs or alters the protein's biological function. The resulting protein damage is exacerbated by a thiyl radical-mediated oxidation. N-Hcy-proteins undergo structural changes leading to aggregation and amyloid formation. These structural changes generate proteins, which are toxic and which induce an autoimmune response. Proteolytic degradation of N-Hcy-proteins generates N epsilon-Hcy-Lys. Levels of Hcy-Thiolactone, N-Hcy-protein, and N epsilon-Hcy-Lys increase under pathological conditions in humans and mice and have been linked to cardiovascular and brain disorders. This chapter reviews fundamental biological chemistry of Hcy-Thiolactone, N-Hcy-protein, and N epsilon-Hcy-Lys and discusses their clinical significance.
