Different protease inhibitors were evaluated: metalloproteases inhibitor (ethylenediamine-tetraacetic acid--EDTA), at 1mM and 10mM; serine proteases inhibitor (fluoride fenilmetilsulfonila--PMSF), at 1mM and 10mM; cysteine proteases inhibitor (iodoacetic acid) at 1mM and 10mM; and the aspartate proteases inhibitor (pepstatin A) at 0.1 mM.
Iodoacetic acid at 1 mM was the inhibitor that had higher action on the enzyme thus indicating that the evaluated proteases can be a cysteine protease.
Effect of some SH-reacting compounds: Pre-incubating the enzyme with SH-reacting compounds such as iodoacetic acid
(5mM) iodoacetamide (10mM) N-ethyl- maleimide (10mM) and p-hydroxymercuri-benzoate (0.5mM) for 10 min at various pH ranging from 3 to 8 before the addition of p-nitrophenyl phosphate showed that these compounds inhibited the enzyme to lesser extent (10-20%) revealing that SH-group containing amino acids in the enzyme may not be significant for its catalytic activity.
When iopamidol was dissolved in river water spiked with chlorine or chloramine, high levels of iodoacetic acid and iodo-trihalomethanes were produced in a dose-dependent manner.
Iodo-DBPs are more toxic than brominated and chlorinated analogs, and iodoacetic acid is the most genotoxic of all DBPs tested so far.
These include iodine-containing acids such as iodoacetic acid
. Other work has linked iodoacetic acid
to birth defects in mice.
For the first HPLC method (44), samples were incubated at pH 8.0 with iodoacetic acid [(IAA); final concentration, 50 mmol/L] for 45 min, and then 0.2 mL of each sample was diluted with 0.2 mL of FDNB (15 mL/L in ethanol) for 3 h.
 Nonstandard abbreviations: GSH, reduced glutathione; GSSG, glutathione disulfide; CDNB, 1-chloro-2,4-dinitrobenzene; GR, glutathione reductase; NEM, N-ethylmaleimide; FDNB, 2,4-dinitrofluorobenzene; MBB, monobromobimane; RBC, red blood cell; IAA, iodoacetic acid; TCA, trichloroacetic acid; SH, sulthydryl; and Hb, hemoglobin.
I made derivatives of these proteins in which their cysteine residues have been modified with iodoacetamide, iodoacetic acid
, and assayed for poly (C)-dependent ATP hydrolysis.
After reduction, the albumin was reacted for 45 min with a 2.5 mol/mol excess of iodoacetic acid
(pH 8.0) over total thiol groups and then dialyzed against water and freeze-dried.
Moreover, no adducts were detected when iodoacetic acid
was used as the alkylation reagent.