Ligand L-cystine

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Basic Ligand Information

Molecular Structure
Picture of L-cystine (click for magnification)
Molecular Formula
BRENDA Name
InChIKey
C6H12N2O4S2
L-cystine
LEVWYRKDKASIDU-IMJSIDKUSA-N
Synonyms:
cystine, L-cystine(side 2), L-cystine[side 2]


Show all pahtways known for Show all BRENDA pathways known for L-cystine

Roles as Enzyme Ligand

In Vivo Substrate in Enzyme-catalyzed Reactions (7 results)

EC NUMBER
PROVEN IN VIVO REACTION
REACTION DIAGRAM
LITERATURE
ENZYME 3D STRUCTURE
cystine + GSH = cysteine + GSSG
show the reaction diagram
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L-cystine + H2O = pyruvate + NH3 + L-thiocysteine
show the reaction diagram
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L-cystine + H2O = ? + NH3
show the reaction diagram
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In Vivo Product in Enzyme-catalyzed Reactions (3 results)

EC NUMBER
PROVEN IN VIVO REACTION
REACTION DIAGRAM
LITERATURE
ENZYME 3D STRUCTURE

Substrate in Enzyme-catalyzed Reactions (40 results)

EC NUMBER
REACTION
REACTION DIAGRAM
LITERATURE
ENZYME 3D STRUCTURE
cystine + NADPH + H+ = 2 cysteine + NADP+
show the reaction diagram
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cystine + glutathione = cysteine + glutathione disulfide
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5-L-glutamyl-4-nitroanilide + L-cystine = 4-nitroaniline + 5-L-glutamyl-L-cystine
show the reaction diagram
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L-cystine + phenylpyruvate = cystine ketimine + phenylalanine
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L-cystine + H2O = ?
show the reaction diagram
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L-cystine + H2O = ? + pyruvate + NH3
show the reaction diagram
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L-cystine = ?
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L-cystine + H2O = ?
show the reaction diagram
-
L-cystine + H2O = ?
show the reaction diagram
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L-cystine + H2O = ?
show the reaction diagram
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L-cystine + H2O = ? + NH3
show the reaction diagram
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ATP + (R)-4'-phosphopantothenate + cystine = (R)-4'-phosphopantothenoyl-L-cystine + ADP + phosphate
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Product in Enzyme-catalyzed Reactions (20 results)

EC NUMBER
REACTION
REACTION DIAGRAM
LITERATURE
ENZYME 3D STRUCTURE
L-cysteine + O2 = L-cystine + H2O
show the reaction diagram
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starch + cysteine + O2 = malto-oligosaccharide aldonic acid + cystine + H2O
show the reaction diagram
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L-cysteine + NADPH = L-cystine + NADP+
show the reaction diagram
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cysteine + homocystine = cystine + 2 homocysteine
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L-cysteine + protein disulfide = cystine + protein-dithiol
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L-cystinyl-p-nitroanilide + H2O = L-cystine + p-nitroaniline
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Cystinyl 4-nitroanilide + H2O = Cystine + 4-nitroaniline
show the reaction diagram
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L-2-iminothiazolidine-4-carboxylate + H2O = L-cystine
show the reaction diagram
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Activator in Enzyme-catalyzed Reactions (7 results)

EC NUMBER
COMMENTARY
LITERATURE
ENZYME 3D STRUCTURE
20 mM, slight activation
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causes an increase in Vmax value and a decrease in Km value, nonessential mode of activation
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16% activation at 1 mM
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5 mM, 142% of initial activity
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25% activation at 1 mM, 73% activation at 5 mM
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Inhibitor in Enzyme-catalyzed Reactions (29 results)

EC NUMBER
COMMENTARY
LITERATURE
ENZYME 3D STRUCTURE
25% residual activity at 2 mM
-
42% inhibition at 5 mM
-
inhibition not reversed by glutathione
-
81% inhibition at 1.5 mM
-
strongly and selectively inhibits the reductive amination reaction
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55% inhibition at 10 mM
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allosteric inhibition
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competitive versus O-acetyl-L-serine, the cystine-binding residues are highly conserved in all OASS proteins; competitive versus O-acetyl-L-serine, the cystine-binding residues are highly conserved in all OASS proteins. Active site of CysK2–cystine binding structure, overview. Cystine occupies the substrate/product binding site of the enzyme
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oxidized form, inhibition almost completely reversible by addition of reduced dithiothreitol
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adenylate kinase activity is diminished in the brain cortex of rats loaded with cystine dimethylester (0.0016 mg/g body weight), co-administration with cysteamine (0.00046 mg/g body weight) prevents inhibition of adenylate kinase caused by cystine
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inhibits the enzyme activity in presence of TNF-alpha
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slight inhibition
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5 mM, 15 min, 100% residual activity in absence of substrate S-pantetheine-3-pyruvate, 32% residual activity in presence of the substrate S-pantetheine-3-pyruvate
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1 mM, 11% inhibition
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Enzyme Kinetic Parameters

kcat Value (Turnover Number) (2 results)

EC NUMBER
TURNOVER NUMBER [1/S]
TURNOVER NUMBER MAXIMUM [1/S]
COMMENTARY
LITERATURE
30.3
-
pH 7.5, 22°C, wild-type enzyme TRP14
29
-
pH 8.3, 30°C

KM Value (27 results)

EC NUMBER
KM VALUE [MM]
KM VALUE MAXIMUM [MM]
COMMENTARY
LITERATURE
5
-
-
0.23
-
-
1.4
-
pH 9.0, 37°C
2
-
enzyme A
2.1
-
pH 8.3, 30°C

References & Links

Links to other databases for L-cystine

ChEBI
PubChem
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PubChem