Cystathionine homocysteine. Medical search. Frequent questions

Bublil EM, Majtan T. Classical homocystinuria: From cystathionine beta-synthase deficiency to novel enzyme therapies. (medlineplus.gov)
Plasma homocysteine levels are elevated ≥ 10-fold in homozygous cystathionine beta-synthase deficiency. (msdmanuals.com)
Vascular complications of cystathionine beta-synthase deficiency: future directions for homocysteine-to-hydrogen sulfide research. (esmed.org)
The purpose of this study was to evaluate the role of free radicals as potential causes of endothelial cell injury in a case-control study of obligate heterozygotes for cystathionine beta-synthase deficiency. (ox.ac.uk)
Firstly, free radical production as measured by neutrophil chemiluminescence in obligate heterozygotes for cystathionine beta-synthase deficiency was compared with age- and sex-matched normal subjects. (ox.ac.uk)
The U.S. Food and Drug Administration has granted Rare Pediatric Disease designation to Orphan Technologies' OT-58 for the treatment of cystathionine beta synthase deficiency homocystinuria. (globalgenes.org)
It is currently in a phase 1/2 double-blind, randomized, placebo-controlled study to assess its safety, tolerability, pharmacokinetics, pharmacodynamics, and clinical effects in HCU patients age 12 who have cystathionine beta-synthase deficiency. (globalgenes.org)
It's usually caused by cystathionine beta-synthase deficiency, but it can also be caused by decreased B12 affinity in cystathionine beta- synthase, or methionine synthase deficiency. (osmosis.org)

In enzymology, a cystathionine gamma-synthase (EC 2.5.1.48) is an enzyme that catalyzes the formation of cystathionine from cysteine and an activated derivative of homoserine, e.g. (wikipedia.org)
O4-succinyl-L-homoserine + L-cysteine ⟶ {\displaystyle \longrightarrow } L-cystathionine + succinate In microorganisms, the activated substrate of this enzyme is O4-succinyl-L-homoserine or O4-acetyl-L-homoserine. (wikipedia.org)
Other names in common use include O-succinyl-L-homoserine succinate-lyase (adding cysteine), O-succinylhomoserine (thiol)-lyase, homoserine O-transsuccinylase, O-succinylhomoserine synthase, O-succinylhomoserine synthetase, cystathionine synthase, cystathionine synthetase, homoserine transsuccinylase, 4-O-succinyl-L-homoserine:L-cysteine, and S-(3-amino-3-carboxypropyl)transferase. (wikipedia.org)
Homocysteine and cysteine synthetases of Neurospora crassa. (wikipedia.org)
Subsequently, cystathionine is hydrolyzed to yield cysteine (Cys) and α -ketobutyrate via vitamin B 6 -dependent cystathionine γ -lyase (CSE) and finally to taurine (Tau) [ 2 , 3 ]. (hindawi.com)
The main generation of H 2 S in cutaneous tissue mostly depends on enzymatic routes using L-cysteine and homocysteine by two pyridoxal-5 - phosphate-dependent enzymes, cystathionine β -synthase (CBS) and cystathionine γ -lyase (CSE). (hindawi.com)
CBS catalyses the generation of cystathionine from the substrates homocysteine and serine and liberates H 2 S from a combination of cysteine and homocysteine. (hindawi.com)
Cystathionine beta-synthase (CBS) is a pivotal enzyme of the transsulfuration pathway responsible for diverting homocysteine to the biosynthesis of cysteine and production of hydrogen sulfide (H 2 S). Aberrant upregulation of CBS and overproduction of H 2 S contribute to pathophysiology of several diseases including cancer and Down syndrome. (rcsb.org)
Converts cystathionine to cysteine, ammonia and 2-oxobutanoate. (nih.gov)
Cystathionine β-synthase (CBS) is a key regulator of sulfur amino acid metabolism, taking homocysteine from the methionine cycle to the biosynthesis of cysteine via the trans-sulfuration pathway. (rhea-db.org)
Some bacteria can synthesize methionine using organic sulfur through transsulfuration of O-succinyl-L-homoserine with L-cysteine to form L-cystathionine. (rhumbarlv.com)
As a universal key intermediate in the MMC, homocysteine is not obtained from the diet, but is remethylated to methionine, or converted to cysteine by the trans-sulfuration pathway. (biomedcentral.com)
in plasma, it undergoes oxidization and transforms to disulfides homocystine and cysteine-homocysteine, the measured plasma level reflects these 3 components. (medscape.com)
Homocysteine is an intermediary amino acid formed during the conversion of methionine to cysteine. (biomedcentral.com)
CBS can also convert homocysteine methionine or cysteine. (drlamcoaching.com)
CBS is a pivotal enzyme in the conversion of the amino acid methionine to homocysteine and then to cysteine. (globalgenes.org)
Finally, the enzyme cystathionase converts cystathionine into cysteine. (osmosis.org)
Now, when there's a problem with cystathionine beta- synthase, homocysteine cannot be combined with serine, so less cysteine is produced, and homocysteine builds up in the body . (osmosis.org)

Homocysteine accumulates due to a deficiency of the enzyme cystathionine b -synthase. (hse.ie)
Homocystinuria is an inherited autosomal recessive defect in methionine metabolism that is caused by a deficiency in cystathionine synthase. (medscape.com)
However, Solomon 1 previously reported on patients with normal values of MMA, homocysteine and serum B12 who still had clinical symptoms of a B12 deficiency and responded favourably to treatment with vitamin B12. (stichtingb12tekort.nl)
Plasma homocysteine levels are elevated in vitamin B-12 deficiency, vitamin B-6 deficiency and in folic acid deficiency. (medscape.com)
Plasma homocysteine levels are usually severely elevated in homozygous cystathionine-β synthase deficiency and moderately elevated in heterozygous cystathionine-β synthase deficiency. (medscape.com)
In most cases, vitamin B-12 deficiency is associated with an elevation in plasma homocysteine and methylmalonic acid levels, whereas folate deficiency is associated with elevated homocysteine levels only. (medscape.com)
Here are 6 enzymes, the first 3 directly convert homocysteine to other amino acids, the other 3 listed here are enzymes which a deficiency of will limit one of those conversions. (radicalhealing.info)
Classical homocystinuria (HCU) is a rare genetic metabolic disorder caused by a deficiency in the enzyme cystathionine beta synthase (CBS). (globalgenes.org)

Structural basis of regulation and oligomerization of human cystathionine beta-synthase, the central enzyme of transsulfuration. (cathdb.info)
7QGT: Crystal structure of human cystathionine beta-synthase (delta516-525) in complex with AOAA. (rcsb.org)
Reversible heme-dependent regulation of human cystathionine beta-synthase by a flavoprotein oxidoreductase. (esmed.org)

Researchers have not determined how excess homocysteine and related compounds lead to the signs and symptoms of homocystinuria. (medlineplus.gov)
Homocystinuria is an autosomal recessive condition resulting from the accumulation in blood of the essential amino acid methionine and one of its metabolic products homocysteine. (hse.ie)
Consequently all infants who present clinically in later life with signs and symptoms suggestive of homocystinuria, such as dislocation of lenses, osteoporosis and inappropriate tall stature should have the disorder excluded formally by measuring plasma levels of total homocysteine. (hse.ie)
About 10 years after the discovery of homocystinuria it was hypothesised by McCully 4 that high plasma homocysteine might be causally related to the vascular complications of the disease. (bmj.com)
Homocystinuria represents a group of hereditary metabolic disorders characterized by an accumulation of homocysteine in the serum and an increased excretion of homocysteine in the urine. (medscape.com)
Plasma and urine homocysteine tests are indicated in the screening and diagnosis of different types of homocystinuria. (medscape.com)
BACKGROUND: Classical homocystinuria (HCU) results from deficient cystathionine -synthase activity, causing elevated levels of Met and homocysteine (Hcy). (cdc.gov)
In homocystinuria , "homocysteine" is a metabolite of the amino acid methionine, and "uria" means, a substance present in urine. (osmosis.org)
So people with homocystinuria have large amounts of homocysteine in their urine, as well as other problems in the connective tissue, muscles, brain, heart, and blood vessels. (osmosis.org)

This should help answer the question: how to people without problematic genetic variants avoid problems associated with elevated homocysteine levels (most notably arteriosclerosis)? (radicalhealing.info)

It is necessary for the conversion of homocysteine to cystathionine. (caasn.com)
Essentially, CBS links the two pathways together, through its conversion of homocysteine into cystathionine. (metabolichealing.com)

In transsulfuration pathway, Hcy is reacted with serine (Ser) to form cystathionine via vitamin B 6 -dependent cystathionine β -synthase (CBS). (hindawi.com)
CBS is the first step of the transsulfuration pathway, converting homocysteine to cystathionine. (drlamcoaching.com)
This article is a follow-up, based upon my own current hypotheses as well as literature-cited observations regarding these complex yet seemingly critical discussions regarding CBS (cystathionine beta synthase) and the transsulfuration pathway. (metabolichealing.com)

The enzymes made by the MTHFR , MTR , MTRR , and MMADHC genes play roles in converting homocysteine to methionine. (medlineplus.gov)
Variants in any of these genes prevent the enzymes from functioning properly, which leads to a buildup of homocysteine in the body. (medlineplus.gov)
This study was aimed at investigating the effects of quercetin on mRNA expression and activity of critical enzymes in homocysteine metabolism in rats fed a methionine-enriched diet. (hindawi.com)
Less severe elevations of homocysteine levels are more commonly observed as a result of heterozygous mutations of these enzymes, dietary deficits of folate or vitamin B 12 , or in patients with liver disease or decreased renal function [ 6 ]. (biomedcentral.com)
H2S is biosynthesized from two enzymes: CBS and CTH (cystathionine gamma lyase), with P5P as the cofactor. (metabolichealing.com)

Thus, 0we hypothesized that long-term administration of a high-methionine diet to T2DM rats with normal renal function may create metabolic changes, culminating in an elevated level of circulating homocysteine. (biomedcentral.com)

L-serine + L-homocysteine = L-cystathionine + H(2)O. (cathdb.info)
This particular enzyme is responsible for using vitamin B6 to convert building block of proteins or amino acids called homocysteine and serine to a molecule called cytathionine. (drlamcoaching.com)
Next, the enzyme cystathionine beta- synthase, which requires vitamin B6 as a substrate, combines homocysteine and serine to create cystathionine. (osmosis.org)

1-3 There are many factors affecting the risk and prognosis of ICH, and high plasma homocysteine (Hcy) concentration, also known as hyperhomocysteinemia (HHcy), is a notable risk factor. (bmj.com)

In remethylation pathway, Hcy can be remethylated to form Met via methionine synthase (MS) or betaine-homocysteine methyltransferase (BHMT), in which cofactors such as folic acid and vitamin B 12 or betaine are required. (hindawi.com)
An alternative remethylation pathway also exists using the cobalamin independent betaine-homocysteine methyltransferase. (bmj.com)

Disorders of cobalamin (vitamin B 12 )/propionate/homocysteine metabolism result from defects in the vitamin B 12 metabolic pathway. (arupconsult.com)
Molecular testing is used to confirm suspected cobalamin/propionate/homocysteine metabolism-related disorders in individuals with clinical symptoms and/or biochemical findings. (arupconsult.com)
Pathogenic germline variants in genes associated with the cobalamin metabolic pathway cause disorders of cobalamin (vitamin B 12 )/propionate/homocysteine metabolism. (arupconsult.com)
1. Cobalamin-responsive disorders in the ambulatory care setting: unreliability of cobalamin, methylmalonic acid, and homocysteine testing. (stichtingb12tekort.nl)
6. Measurement of methylmalonic acid, homocysteine and methionine in cobalamin and folate deficiencies and homocysteinuria. (stichtingb12tekort.nl)
MTHFR polymorphisms and serum cobalamin affect plasma homocysteine concentrations differentially in females and males. (medscape.com)
Pirouzpanah S, Taleban FA, Mehdipour P, Atri M, Foroutan-Ghaznavi M. Plasma Total Homocysteine Level in Association With Folate, Pyridoxine, and Cobalamin Status Among Iranian Primary Breast Cancer Patients. (medscape.com)
Any homocysteine that does not undergo this process can be converted back into methionine by methionine synthase, which requires vitamin B12 , or cobalamin , and folate as substrates. (osmosis.org)

Pathways for the metabolism of homocysteine. (bmj.com)
Conversion of S-adenosyl-L-homocysteine (SAH) to homocysteine increased and the metabolism of homocysteine was reduced under diabetic conditions, and consequently homocysteine accumulated in the elimination phase. (biomedcentral.com)

The CBS gene provides instructions for making an enzyme called cystathionine beta-synthase. (medlineplus.gov)

Some of the excess homocysteine is excreted in urine. (medlineplus.gov)
The reference range of urine homocysteine (24-hour urine collection) varies with the technique used, from 0-9 µmol/g creatinine. (medscape.com)
Whether elevated plasma and urine homocysteine levels represent a cardiovascular risk factor is debatable. (medscape.com)
As a result, homocysteine and other potentially toxic compounds build up in the bloodstream and are excreted in the urine. (drlamcoaching.com)

Serum homocysteine was significantly increased after methionine treatment and decreased after the addition of quercetin. (hindawi.com)
It is concluded that quercetin reduces serum homocysteine by increasing remethylation and transsulfuration of homocysteine in rats exposed to a methionine-enriched diet. (hindawi.com)
MMA and homocysteine are considered more sensitive tests than serum B12. (stichtingb12tekort.nl)

Homocysteine is a sulphur containing amino acid that plays an important role in methionine and folate metabolism. (bmj.com)
Simplified picture showing homocysteine involvement in different metabolic pathways, as well as the role of vitamins B-6, B-12, and folate as a co-factors in this pathway. (medscape.com)
Homocysteine play an important role in many metabolic pathways, mainly the methionine cycle to the folate cycle (see image below). (medscape.com)
Caption: Homocysteine involvement in different metabolic pathways, as well as the role of vitamin B-6, vitamin B-12, and folate as cofactors in these pathways. (medscape.com)
Plasma homocysteine levels can be elevated in vitamin B-12, folate (vitamin B-9), and vitamin B-6 deficiencies. (medscape.com)
We give a new explanation of the well known phenomenon that folate supplementation lowers homocysteine and we show how to use the model to investigate the effects of vitamin deficiencies, gene polymorphisms, and nutrient input changes. (biomedcentral.com)

Can also accept homocysteine as substrate. (nih.gov)
Through the CBS enzyme reaction, the substrate that is generated from homocysteine is cystathionine. (metabolichealing.com)

The mRNA expression and enzymatic activity of cystathionine β -synthase and cystathionine γ -lyase were upregulated after quercetin, methionine, or quercetin plus methionine treatment and a more significant increase was observed for hepatic cystathionine β -synthase in the methionine plus quercetin treated rats, suggesting an interaction between methionine and quercetin. (hindawi.com)
Crystal Structures of Cystathionine beta-Synthase from Saccharomyces cerevisiae: One Enzymatic Step at a Time. (rhea-db.org)

The megaloblastic anemia profile blood test includes testing the levels of cystathionine, homocysteine, 2-methylcitric acid, and methylmalonic acid in the blood. (walkinlab.com)
The megaloblastic anemia profile monitors four compounds, cystathionine, homocysteine, 2-methylcitric acid, and methylmalonic acid, which will allow for a diagnosis of megaloblastic anemia to be determined. (walkinlab.com)
Methylmalonic acid and homocysteine are critical tests to make a diagnosis. (walkinlab.com)

The meta-analysis showed that blood concentrations of oxidative glutathione (GSSG), malondialdehyde, homocysteine, S -adenosylhomocysteine, nitric oxide, and copper were higher in children with ASD than that of HC children. (nature.com)

Often homocysteine and cystathionine convert too quickly to taurine, leaving not enough glutathione for the body. (drlamcoaching.com)

Variants in the CBS gene disrupt the function of cystathionine beta-synthase, preventing homocysteine from being used properly. (medlineplus.gov)
RNA-seq was performed in blood Ly6C high and Ly6C low MC sorted by flow cytometry from control and HHcy cystathionine β-synthase gene-deficient ( Cbs -/- ) mice. (frontiersin.org)
In Phase I, the approach will be developed on a single high-value target gene, Cystathionine beta-Synthase, necessary for homocysteine clearance and cardio-respiratory fitness. (sbir.gov)
Through genetic testing and mutation identification, scientists have found what is known as a cystathionine beta-synthase (CBS) gene mutation, or CBS mutation. (drlamcoaching.com)
In that article I discussed how there appears to be two differing perspectives on the nature of CBS (cystathionine beta synthase) gene mutations: the literature's contention of "down-regulated" CBS enzyme activity among carriers of certain mutations, and certain empirical, clinical observations of the opposite situation, specifically that certain CBS gene mutations can cause an "up-regulation" to enzyme activity. (metabolichealing.com)

homocysteine to a molecule called cystathionine. (medlineplus.gov)

Using the methionine loading test, in which 0.1 mg/kg body weight of this amino acid is administered orally, they found that the prevalence of high circulating homocysteine concentrations, or hyperhomocysteinaemia, was higher than in normal controls. (bmj.com)
The aim of the current study was to predict changes in plasma methionine and homocysteine concentrations after simulated consumption of methionine-rich foods, following the development of a mathematical model for MMC in Zucker Diabetic Fatty (ZDF) rats, as a representative T2DM animal model. (biomedcentral.com)
Using our model, we performed simulations to compare the changes in plasma methionine and homocysteine concentrations between ZDF and normal rats, by multiple administrations of the methionine-rich diet of 1 mmol/kg, daily for 60 days. (biomedcentral.com)

When pyridoxine supplementation was initiated at age 18 years, the patient's plasma homocysteine levels decreased below the reference range. (medscape.com)
Randomized controlled trials have demonstrated that supplementation with B vitamins, including vitamin B 6 , could effectively reduce homocysteine levels. (oregonstate.edu)

High levels of circulating homocysteine are associated with an increased risk of cardiovascular disease . (oregonstate.edu)
Low levels of vitamin B6 in the blood are associated with inflammation, elevated levels of C - reactive protein (CRP), increased blood levels of homocysteine, and increased risk of cardiovascular disease. (caasn.com)
The abnormality is established by measuring fasting plasma homocysteine levels in patients with cardiovascular disease or thromboembolism who are suspected of having the disorder. (msdmanuals.com)

At age 50 years, the patient's plasma homocysteine levels still remained low. (medscape.com)
Although alterations in the methionine metabolism cycle (MMC) have been associated with vascular complications of diabetes, there have not been consistent results about the levels of methionine and homocysteine in type 2 diabetes mellitus (T2DM). (biomedcentral.com)
The levels of methionine and homocysteine were elevated approximately two- and three-fold, respectively, in ZDF rats, while there were no changes observed in the normal control rats. (biomedcentral.com)
To verify this hypothesis, mathematical modeling of methionine metabolism was required to predict the levels of homocysteine derived from given amounts of methionine. (biomedcentral.com)
Zhang F, Li X, Dong Q, Wang Y, Zhang H. Risk of Acute Cerebral Infarction and Plasma Asymmetrical Dimethylarginine and Homocysteine Levels: A Clinical Correlation Analysis of Chinese Population. (medscape.com)
High homocysteine levels. (caasn.com)
Therefore, routine measurement of homocysteine levels in patients with venous and arterial thromboembolism is discouraged. (msdmanuals.com)
Due to the high levels of taurine and ammonia this mutation causes, it is common to see lower levels of cystathionine and homocysteine. (drlamcoaching.com)
Classical HCU leads to significantly elevated levels of the amino acid homocysteine that can result in debilitating comorbidities in patients including severe cardiovascular, skeletal, neurologic and ophthalmologic complications. (globalgenes.org)
OT-58 is a modified recombinant enzyme therapy in development for patients suffering from classical HCU that is designed to help patients reduce their homocysteine levels and restore a normal lifestyle. (globalgenes.org)

It is elevated in deficiencies of cystathionine synthase, methionine synthase, and vitamin B6. (medpreptogo.com)

Most of these mutations transform single amino acids in CBS, or cystathionine beta-synthase. (drlamcoaching.com)
All these mutations disrupt the normal function of the cystathionine beta-synthase enzyme. (drlamcoaching.com)

We found that the neurite outgrowth velocity and motor functional recovery in the ICH plus HHcy group were significantly slower than that in the control group, indicating that homocysteine (Hcy) significantly impedes the neurite outgrowth recovery after ICH. (bmj.com)

High homocysteine also increases the risk of oxidative damage in the endothelial wall of blood vessels and contributes to vascular plaque formation. (drlamcoaching.com)

These studies will facilitate Phase II to query all genes related to homocysteine clearance, and to spur a field trial in which individual genotype and metabolite profile are diagnostic for potential performance enhancement. (sbir.gov)

The reference range of plasma homocysteine may vary with the technique used. (medscape.com)

Homocysteine is metabolized by means of 2 pathways: remethylation and transsulfuration. (medscape.com)
The remethylation pathway comprises 2 intersecting biochemical pathways and results in the transfer of a methyl group (CH 3 ) to homocysteine from methylcobalamin, which receives its methyl group from S-adenosylmethionine (SAM), from 5-methyltetrahydrofolate (an active form of folic acid), or from betaine (trimethylglycine). (medscape.com)

The latter compound is methylated by the homocysteine methyltransferase of these microorganisms. (rhumbarlv.com)

Upon investigating the CBS mutation, researchers discovered the path to disruption of the normal function of cystathionine beta-synthase, which causes a buildup in the blood of homocysteine and other potentially toxic compounds. (drlamcoaching.com)

However, homocysteine lowering by B vitamins has failed to lower the risk of adverse cardiovascular outcomes in high-risk individuals. (oregonstate.edu)
Homocysteine lowering by B vitamins and the secondary prevention of deep vein thrombosis and pulmonary embolism: A randomized, placebo-controlled, double-blind trial. (msdmanuals.com)

Homocysteine is toxic to the lining of the blood vessels and predisposes the individual to thrombus formation and blood clots and a number of other complications including osteoporosis (thinning of the bones) and eye complication. (hse.ie)

Anatomy2

Organisms2

Diseases9

Chemicals and Drugs56

Analytical, Diagnostic and Therapeutic Techniques and Equipment5

Phenomena and Processes14

Technology, Industry, Agriculture1

Information Science3

Health Care1

Beta-synthase deficiency8

Cysteine18

Deficiency8

Human cystathionine beta-syn3

Homocystinuria9

Elevated homocysteine levels1

Conversion of homocysteine2

Transsulfuration pathway3

Enzymes5

Level of circulating1

Serine3

High plasma homocysteine1

Betaine-homocysteine meth2

Cobalamin8

Metabolism of homocysteine2

Instructions for making an enzyme1

Urine4

Serum3

Folate6

Substrate2

Enzymatic2

Methylmalonic acid3

Nitric oxide1

Glutathione1

Gene5

Molecule called1

Concentrations3

Supplementation2

Cardiovascular disease3

Levels10

Methionine synthase1

Mutations2

HHcy1

Oxidative1

Genes1

Plasma1

Remethylation2

Microorganisms1

Buildup1

Lowering by B vitamins2

Toxic1