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Skeletal formula
Space-filling model
CAS number 144-48-9 YesY
PubChem 3727
ChemSpider 3596 YesY
EC number 205-630-1
RTECS number AC4200000
Jmol-3D images Image 1
Molecular formula C2H4INO
Molar mass 184.96 g mol−1
Appearance white crystals (yellow colouration indicates the presence of iodine)
Melting point 94 °C (201 °F; 367 K)
MSDS brief MSDS, extended MSDS
NFPA 704
Infobox references

2-Iodoacetamide 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.[1][2] Also used in ubiquitin studies as an inhibitor of deubiquitinase enzymes (DUBs) because it alkylates the cysteine residues at the DUB active site.

Peptidase inhibitor[edit]

Iodoacetamide 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 acid derivative, iodoacetate, iodoacetamide reacts substantially more quickly. This observation appears contradictory to standard chemical reactivity, however the presence of a favourable interaction between the positive imidazolium ion of the catalytic histidine and the negatively charged carboxyl-group of the iodoacetate is the reason for the increased relative activity of iodoacetamide.[3]

Mechanism of irreversible inhibition of cysteine peptidases with iodoacetamide.


  1. ^ Smythe CV (1936). "The reactions of Iodoacetate and of Iodoacetamide with various Sulfhydryl groups, with Urease, and with Yeast preparations". J. Biol. Chem. 114 (3): 601–12. 
  2. ^ Anson ML (1940). "The reactions of Iodine and Iodoacetamide with native Egg Albumin". J. Gen. Physiol. 23 (3): 321–31. doi:10.1085/jgp.23.3.321. PMC 2237930. PMID 19873158. 
  3. ^ Polgar, L (1979). "Deuterium isotope effects on papain acylation. Evidence for lack of general base catalysis and for enzyme-leaving group. interaction". Eur. J. Biochem. 98 (2): 369–374. doi:10.1111/j.1432-1033.1979.tb13196.x. PMID 488108. 

External links[edit]