Cysteic acid also known as 3-sulfo--alanine is the
organic compound with the formula HO
3SCH
2CH(NH
2)CO
2H. It is often referred to as cysteate, which near neutral pH takes the form
−O
3SCH
2CH(NH
3+)CO
2−.
It is an
amino acid generated by oxidation of
cysteine
Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile.
When present as a deprotonated catalytic residue, sometime ...
, whereby a thiol group is fully oxidized to a
sulfonic acid
In organic chemistry, sulfonic acid (or sulphonic acid) refers to a member of the class of organosulfur compounds with the general formula , where R is an organic alkyl or aryl group and the group a sulfonyl hydroxide. As a substituent, it is kn ...
/sulfonate group. It is further metabolized via 3-sulfolactate, which converts to pyruvate and sulfite/bisulfite. The enzyme
L-cysteate sulfo-lyase
The enzyme L-cysteate sulfo-lyase (EC 4.4.1.25) catalyzes the reaction
:L-cysteate + H2O = hydrogensulfite + pyruvate + NH3 (overall reaction)
::(1a) L-cysteate = hydrogensulfite + 2-aminoprop-2-enoate
::(1b) 2-aminoprop-2-enoate = 2-iminopropan ...
catalyzes this conversion. Cysteate is a biosynthetic precursor to
taurine in microalgae. By contrast, most taurine in animals is made from
cysteine sulfinate.
References
Sulfur amino acids
Sulfonic acids
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