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Iodoacetamide (IAA) is an organic compound with the chemical formula I C H 2 CO NH 2. It is an alkylating agent used for peptide mapping purposes. Its actions are similar to those of iodoacetate. It is commonly used to bind covalently with the thiol group of cysteine so the protein cannot form disulfide bonds.
An isotope-coded affinity tag (ICAT) is an in-vitro isotopic labeling method used for quantitative proteomics by mass spectrometry that uses chemical labeling reagents. [1] [2] [3] These chemical probes consist of three elements: a reactive group for labeling an amino acid side chain (e.g., iodoacetamide to modify cysteine residues), an isotopically coded linker, and a tag (e.g., biotin) for ...
In course of the subsequent irreversible alkylation of the SH groups with iodoacetamide the cysteines are transformed to the stable S-carboxyamidomethylcysteine (CAM; adduct: -CH 2-CONH 2). The molecular weight of the cysteine amino-acid residue is thereby increased from 103.01 Da to 160.03 Da.
Iodoacetate is an irreversible inhibitor of all cysteine peptidases, with the mechanism of inhibition occurring from alkylation of the catalytic cysteine residue (see schematic). In comparison with its amide derivative, iodoacetamide, iodoacetate reacts substantially slower. This observation appears contradictory to standard chemical reactivity ...
Given that transcript and protein expression information leave gaps in knowledge surrounding the effects of post-translational modifications and protein-protein interactions on enzyme activity, and that enzyme activity varies across cell types, disease states, and physiological conditions, specialized tools are required to profile enzyme ...
Cysteine-302 is one of three consecutive Cys residues and is crucial to the enzyme's catalytic function. The residue is alkylated by iodoacetamide in both the cytosolic and mitochondrial isozymes, with modifications to Cys-302 indicative of catalytic activity with other residues.
In the 1950s, a serine residue was identified as the catalytic nucleophile of trypsin and chymotrypsin (first purified in the 1930s) [6] by diisopropyl fluorophosphate modification. [7] The structure of chymotrypsin was solved by X-ray crystallography in the 1960s, showing the orientation of the catalytic triad in the active site . [ 8 ]
Phosphorylation occurs when a PO 3 (phosphoryl) group is added to a protein. [3] This chemical modification is the most extensively studied and is reversible. The result of those studies has shown that phosphorylation acts as a regulator for proteins in two ways: the addition or removal of phosphoryl group can impact enzyme kinetics by turning on or off the enzymatic function via ...