L-homocysteine

Three steps

• (S)-malateReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. (2S)-2-aminobutanoate + glyoxylate = 2-oxobutanoate + glycine
  3. glyoxylate + acetyl-CoA + H2O = (S)-malate + CoA + H(+)

  Catalysed by CTH, AGXT2, CLYBLOne of 9 routes

• CHEBI:15611Reach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate + glycine + H2O = (6S)-5,6,7,8-tetrahydrofolate + L-serine
  3. S-Adenosyl-L-methionine:glycine N-methyltransferase

  Catalysed by MTR, SHMT1, SHMT2, GNMTcytosol

• (4aS,6R)-4a-hydroxy-L-erythro-5,6,7,8-tetrahydrobiopterinReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of methionine and tryptophan (cytosol to extracellular)
  3. (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin + L-tryptophan + O2 = 5-hydroxy-L-tryptophan + (4aS,6R)-4a-hydroxy-L-erythro-5,6,7,8-tetrahydrobiopterin

  Catalysed by MTR, SLC7A5, TPH1, TPH2extracellular space, cytosolOne of 2 routes

• CHEBI:15650Reach from here →
  1. L-homocysteine + L-serine = L,L-cystathionine + H2O
  2. N-acetylglutamate synthase (N-acetyl-L-cystathionine)
  3. N-acetyl-LTE4 to leukotriene E4 conversion

  Catalysed by CBS, NAGS, ZDHHC11B, NAA10 and 30 moremitochondrial matrix, cytosolOne of 2 routes

• trimethylenediamineReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of lysine and methionine (cytosol to extracellular)
  3. deoxyhypusine synthase (1,3-diaminopropane)

  Catalysed by MTR, SLC7A6, DHPSextracellular space, cytosol

• CHEBI:15727Reach from here →
  1. L-homocysteine + L-serine = L,L-cystathionine + H2O
  2. N-acetylglutamate synthase (N-acetyl-L-cystathionine)
  3. N-alpha-acetyltransferase 10, NatA catalytic subunit (acetylcarnosine)

  Catalysed by CBS, NAGS, NAA10mitochondrial matrix, cytosolOne of 2 routes

• CHEBI:15746Reach from here →
  1. L-homocysteine + L-serine = L,L-cystathionine + H2O
  2. N-acetylglutamate synthase (N-acetyl-L-cystathionine)
  3. diamine N-acetyltransferase (N1-acetylspermine)

  Catalysed by CBS, NAGS, SAT1, SAT2mitochondrial matrix, cytosolOne of 2 routes

• CHEBI:15765Reach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of methionine and tyrosine (cytosol to extracellular)
  3. L-Tyrosine,tetrahydrobiopterin:oxygen oxidoreductase (3-hydroxylating)

  Catalysed by MTR, SLC7A5, THextracellular space, cytosolOne of 5 routes

• malonateReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. hydrogen sulfide + 2 O2 = sulfate + H(+)
  3. malonate(in) + sulfate(out) = malonate(out) + sulfate(in)

  Catalysed by CTH, SOD1, SLC25A14, SLC25A30 and 1 moreinner side of the membrane, outer side of the membraneOne of 2 routes

• N-carbamoyl-L-aspartic acidReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. L-aspartate(in) + L-methionine(out) = L-aspartate(out) + L-methionine(in)
  3. carbamoyl-phosphate:L-aspartate carbamoyltransferase

  Catalysed by MTR, SLC7A13, CADinner side of the membrane, outer side of the membrane, cytosol

• alpha-D-glucosamine 6-phosphateReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of glutamine and methionine (cytosol to extracellular)
  3. L-glutamine:D-fructose-6-phosphate isomerase (deaminating)

  Catalysed by MTR, SLC7A5, GFPT2, GFPT1extracellular space, cytosol

• thioredoxin dithiolReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. L-Methionine:tRNAMet ligase (AMP-forming)
  3. glycyl-tRNA(gly) phosphorylation

  Catalysed by MTR, MARS1cytosolOne of 2 routes

• a halide anionReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. thiosulfate + 2 glutathione = glutathione disulfide + hydrogen sulfide + sulfite + 2 H(+)
  3. RX + glutathione = an S-substituted glutathione + a halide anion + H(+)

  Catalysed by CTH, TSTD1, GSTT4, GSTA4 and 21 more

• ureaReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of arginine and methionine (cytosol to extracellular)
  3. L-Arginine amidinohydrolase

  Catalysed by MTR, SLC7A6, ARG1extracellular space, cytosolOne of 3 routes

• 2-methyl-3-oxopropanoic acidReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. 2-oxobutanoate + L-alanine = (2S)-2-aminobutanoate + pyruvate
  3. (R)-3-Amino-2-methylpropanoate:pyruvate aminotransferase

  Catalysed by CTH, AGXT2mitochondrial matrix

• L-cystineReach from here →
  1. L-homocysteine + L-serine = L,L-cystathionine + H2O
  2. L-cystathionine cysteine-lyase (deaminating
  3. thioredoxin-disulfide reductase (NADPH) (cystine)

  Catalysed by CBS, CTH, TXNRD1, TXNRD3 and 1 morecytosolOne of 9 routes

• 11-cis-retinolReach from here →
  1. L-homocysteine + L-serine = L,L-cystathionine + H2O
  2. N-acetylglutamate synthase (N-acetyl-L-cystathionine)
  3. Palmitoyl-CoA:retinol O-acyltransferase

  Catalysed by CBS, NAGS, DGAT1, LRAT and 3 moremitochondrial matrix, cytosol

• cob(II)alaminReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. N(6)-L-threonylcarbamoyladenosine(37) in tRNA + (sulfur carrier)-SH + AH2 + 2 S-adenosyl-L-methionine = 2-methylsulfanyl-N(6)-L-threonylcarbamoyladenosine(37) in tRNA + (sulfur carrier)-H + 5'-deoxyadenosine + L-methionine + A + S-adenosyl-L-homocysteine + 2 H(+)
  3. 2 cob(II)alamin + A + 2 H2O + 2 H(+) = 2 aquacob(III)alamin + AH2

  Catalysed by MTR, CDKAL1, MTRR

• (R)-3-aminoisobutyric acidReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of alanine and methionine (cytosol to extracellular)
  3. (R)-3-Amino-2-methylpropanoate:pyruvate aminotransferase

  Catalysed by MTR, SLC7A5, AGXT2extracellular space, cytosol, mitochondrial matrix

• iodideReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of methionine and tyrosine (cytosol to extracellular)
  3. thyroid peroxidase (iodine)

  Catalysed by MTR, SLC7A5, TPOextracellular space, cytosolOne of 25 routes

• oxaloacetateReach from here →
  1. L-homocysteine + L-serine = L,L-cystathionine + H2O
  2. N-acetylglutamate synthase (N-acetyl-L-cystathionine)
  3. ATP citrate lyase (citrate)

  Catalysed by CBS, NAGS, ACLYmitochondrial matrix, cytosolOne of 10 routes

• nitric oxideReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of arginine and methionine (cytosol to extracellular)
  3. L-Arginine, NADPH:Oxygen Oxidoreductase (Nitric-Oxide-Forming)

  Catalysed by MTR, SLC7A6, NOS3, NOS1 and 1 moreextracellular space, cytosolOne of 3 routes

• CHEBI:16523Reach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate + glycine + H2O = (6S)-5,6,7,8-tetrahydrofolate + L-serine
  3. transport of D-serine and glycine (cytosol to extracellular)

  Catalysed by MTR, SHMT1, SHMT2, SLC3A2 and 1 moreextracellular space, cytosolOne of 4 routes

• N(2)-acetyl-L-ornithineReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of methionine and ornithine (cytosol to extracellular)
  3. N2-Acetyl-L-ornithine amidohydrolase

  Catalysed by MTR, SLC7A6, ACY1extracellular space, cytosol

• 2-phenylacetamideReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of methionine and phenylalanine (cytosol to extracellular)
  3. L-phenylalanine:oxygen 2-oxidoreductase (decarboxylating)

  Catalysed by MTR, SLC7A5, EPXextracellular space, cytosol

• CHEBI:16633Reach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of alanine and methionine (cytosol to extracellular)
  3. L-selenocysteine selenide-lyase (L-alanine-forming)

  Catalysed by MTR, SLC7A5, SCLYextracellular space, cytosolOne of 2 routes

• (S)-lactateReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. 2-oxobutanoate + L-alanine = (2S)-2-aminobutanoate + pyruvate
  3. (S)-lactate + NAD(+) = pyruvate + NADH + H(+)

  Catalysed by CTH, AGXT2, LDHA, LDHB and 3 more

• quinolinic acidReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. hydrogen sulfide + 2 O2 = sulfate + H(+)
  3. Transport of Quinolinic Acid

  Catalysed by CTH, SOD1, SLC22A6extracellular space, cytosolOne of 2 routes

• 3'-deoxy-3',4'-didehydro-CTPReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. N(6)-L-threonylcarbamoyladenosine(37) in tRNA + (sulfur carrier)-SH + AH2 + 2 S-adenosyl-L-methionine = 2-methylsulfanyl-N(6)-L-threonylcarbamoyladenosine(37) in tRNA + (sulfur carrier)-H + 5'-deoxyadenosine + L-methionine + A + S-adenosyl-L-homocysteine + 2 H(+)
  3. CTP + AH2 + S-adenosyl-L-methionine = 3'-deoxy-3',4'-didehydro-CTP + 5'-deoxyadenosine + L-methionine + A + H2O + H(+)

  Catalysed by MTR, CDKAL1, RSAD2

• N-[(S)-lactoyl]-L-phenylalanineReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of methionine and phenylalanine (cytosol to extracellular)
  3. (S)-lactate + L-phenylalanine = N-[(S)-lactoyl]-L-phenylalanine + H2O

  Catalysed by MTR, SLC7A5, CNDP2extracellular space, cytosol

• tryptamineReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of methionine and tryptophan (cytosol to extracellular)
  3. L-tryptophan decarboxy-lyase

  Catalysed by MTR, SLC7A5, DDCextracellular space, cytosol

• 2-oxoglutaramateReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of glutamine and methionine (cytosol to extracellular)
  3. L-Glutamine:pyruvate aminotransferase

  Catalysed by MTR, SLC7A5, KYAT1extracellular space, cytosolOne of 5 routes

• (S)-2-hydroxyglutarateReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. N(6)-L-threonylcarbamoyladenosine(37) in tRNA + (sulfur carrier)-SH + AH2 + 2 S-adenosyl-L-methionine = 2-methylsulfanyl-N(6)-L-threonylcarbamoyladenosine(37) in tRNA + (sulfur carrier)-H + 5'-deoxyadenosine + L-methionine + A + S-adenosyl-L-homocysteine + 2 H(+)
  3. (S)-2-hydroxyglutarate + A = 2-oxoglutarate + AH2

  Catalysed by MTR, CDKAL1, L2HGDH

• formaldehydeReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. methanethiol + O2 + H2O = hydrogen sulfide + formaldehyde + H2O2 + H(+)
  3. methanethiol + O2 + H2O = hydrogen sulfide + formaldehyde + H2O2 + H(+)

  Catalysed by CTH, SELENBP1One of 2 routes

• 3-fumarylpyruvateReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. 2-oxobutanoate + L-alanine = (2S)-2-aminobutanoate + pyruvate
  3. 3-fumarylpyruvate + H2O = fumarate + pyruvate + H(+)

  Catalysed by CTH, AGXT2, FAHD1

• CHEBI:16856Reach from here →
  1. L-homocysteine + L-serine = L,L-cystathionine + H2O
  2. L-cystathionine cysteine-lyase (deaminating
  3. cystine to cysteine conversion

  Catalysed by CBS, CTHcytosolOne of 4 routes

• glyoxylic acidReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate + glycine + H2O = (6S)-5,6,7,8-tetrahydrofolate + L-serine
  3. glycine:oxygen oxidoreductase (deaminating)

  Catalysed by MTR, SHMT1, SHMT2, DAOperoxisome

• N-acetyl-L-aspartateReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. L-aspartate(in) + L-methionine(out) = L-aspartate(out) + L-methionine(in)
  3. acetyl-CoA:L-aspartate N-acetyltransferase

  Catalysed by MTR, SLC7A13, NAT8Linner side of the membrane, outer side of the membrane, mitochondrial matrixOne of 2 routes

• oxalic acidReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of chloride and methionine (cytosol to extracellular)
  3. transport of chloride and oxalate (cytosol to extracellular)

  Catalysed by MTR, SLC6A14, SLC26A6extracellular space, cytosolOne of 2 routes

• (R)-3-hydroxybutyric acidReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. 2-hydroxybutyrate:NAD+ oxidoreductase
  3. transport of (R)-3-hydroxybutanoate (cytosol to extracellular)

  Catalysed by CTH, LDHB, LDHC, LDHAL6A and 7 morecytosol, extracellular spaceOne of 4 routes

• 3-hydroxypyruvateReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. 2-oxobutanoate + L-alanine = (2S)-2-aminobutanoate + pyruvate
  3. L-serine + pyruvate = 3-hydroxypyruvate + L-alanine

  Catalysed by CTH, AGXT2, AGXT

• L-glutamic 5-semialdehydeReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of methionine and ornithine (cytosol to extracellular)
  3. L-Ornithine:2-oxo-acid aminotransferase

  Catalysed by MTR, SLC7A6, OATextracellular space, cytosol, mitochondrial matrix

• anilineReach from here →
  1. L-homocysteine + L-serine = L,L-cystathionine + H2O
  2. N-acetylglutamate synthase (N-acetyl-L-cystathionine)
  3. Acetyl-CoA:arylamine N-acetyltransferase

  Catalysed by CBS, NAGS, NAT2, NAT1mitochondrial matrix, cytosol

• aceneuramateReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. 2-oxobutanoate + L-alanine = (2S)-2-aminobutanoate + pyruvate
  3. aceneuramate = aldehydo-N-acetyl-D-mannosamine + pyruvate

  Catalysed by CTH, AGXT2, NPL

• CHEBI:17312Reach from here →
  1. L-homocysteine + L-serine = L,L-cystathionine + H2O
  2. N-acetylglutamate synthase (N-acetyl-L-cystathionine)
  3. N1,N12-diacetylspermine to N1-acetylspermine conversion

  Catalysed by CBS, NAGSmitochondrial matrix, cytosolOne of 2 routes

• 5'-deoxyadenosineReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. N(6)-L-threonylcarbamoyladenosine(37) in tRNA + (sulfur carrier)-SH + AH2 + 2 S-adenosyl-L-methionine = 2-methylsulfanyl-N(6)-L-threonylcarbamoyladenosine(37) in tRNA + (sulfur carrier)-H + 5'-deoxyadenosine + L-methionine + A + S-adenosyl-L-homocysteine + 2 H(+)
  3. N(6)-dimethylallyladenosine(37) in tRNA + (sulfur carrier)-SH + AH2 + 2 S-adenosyl-L-methionine = 2-methylsulfanyl-N(6)-dimethylallyladenosine(37) in tRNA + (sulfur carrier)-H + 5'-deoxyadenosine + L-methionine + A + S-adenosyl-L-homocysteine + 2 H(+)

  Catalysed by MTR, CDKAL1, CDK5RAP1One of 5 routes

• sulfiteReach from here →
  1. L-homocysteine + H2O = 2-oxobutanoate + hydrogen sulfide + NH4(+) + H(+)
  2. Sulfide:glutathione,quinone oxidoreductase
  3. Persulfide dioxygenase

  Catalysed by CTH, SQOR, ETHE1mitochondrial matrixOne of 10 routes

• CHEBI:17380Reach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of methionine and tryptophan (cytosol to extracellular)
  3. Transport of 3-Hydroxy-L-Kynurenine

  Catalysed by MTR, SLC7A5extracellular space, cytosolOne of 2 routes

• (S)-1-pyrroline-5-carboxylateReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of methionine and proline (cytosol to extracellular)
  3. L-proline:(acceptor) oxidoreductase

  Catalysed by MTR, SLC7A5, PRODH2extracellular space, cytosolOne of 2 routes

• agmatineReach from here →
  1. (6S)-5-methyl-5,6,7,8-tetrahydrofolate + L-homocysteine = (6S)-5,6,7,8-tetrahydrofolate + L-methionine
  2. transport of arginine and methionine (cytosol to extracellular)
  3. L-arginine carboxy-lyase (agmatine-forming)

  Catalysed by MTR, SLC7A6extracellular space, cytosol, mitochondrial matrix