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Found in plants, bacteria, and yeast, cystathionine beta-lyase is an essential part of the methionine biosynthesis pathway as homocysteine can be directly converted into methionine by methionine synthase.
The CHAP domain is found in a wide range of protein architectures; it is commonly associated with bacterial type SH3 domains and with several families of amidase domains. It has been suggested that CHAP domain containing proteins utilise a catalytic cysteine residue in a nucleophilic-attack mechanism. [1] [2]
The cysteine sulfhydryl group is nucleophilic and easily oxidized. The reactivity is enhanced when the thiol is ionized, and cysteine residues in proteins have pK a values close to neutrality, so are often in their reactive thiolate form in the cell. [23] Because of its high reactivity, the sulfhydryl group of cysteine has numerous biological ...
The two thioether linkages are typically made by cysteine residues of the protein. These linkages do not allow the heme C to easily dissociate from the holoprotein , cytochrome c , compared with the more easily dissociated heme B that may dissociate from the holoprotein, the heme-protein complex, even under mild conditions.
Papain-like proteases share a common catalytic dyad active site featuring a cysteine amino acid residue that acts as a nucleophile. [1] The human genome encodes eleven cysteine cathepsins which have a broad range of physiological functions. [3] In some parasites papain-like proteases have roles in host invasion, such as cruzipain from ...
In plants, sulfate is absorbed by the roots and then transported to the chloroplasts by the transipration stream where the sulfur are reduced to sulfide with the help of a series of enzymatic reactions. Furthermore, the reduced sulfur is incorporated into cysteine, [2] an amino acid that is a precursor to many other sulfur-containing compounds ...
Zinc and Cadmium are tetrahedrally coordinated to cysteine residues, and each metallothionein protein molecule may bind up to 7 atoms of Zn or Cd. [5] The biosynthesis of metallothionein appears to increase several-fold during periods of oxidative stress to shield the cells against cytotoxicity and DNA damage.
Bacterial-type ferredoxins may in turn be subdivided into further groups, based on their sequence properties. Most contain at least one conserved domain, including four cysteine residues that bind to a [Fe 4 S 4] cluster. In Pyrococcus furiosus Fe 4 S 4 ferredoxin, one of the conserved Cys residues is substituted with aspartic acid.