Which of the following reagents is correctly defined?
A) iodoacetic acid: reduces disulfide bonds
B) guanadinium hydrochloride: disrupts ionic interactions and hydrogen bonds
C) phenylisothiocyanate: reacts with free carboxyl groups
D) cyanogen bromide: reacts with internal cysteine residues
E) performic acid: reacts with free cysteine residues

Question

Quizplus · Accepted Answer

Guanidine hydrochloride disrupts ionic interactions and hydrogen bonds, which can cause denaturation of proteins. Iodoacetic acid is actually used to form disulfide bonds, so answer choice A is incorrect. Phenylisothiocyanate reacts with free amino groups, not carboxyl groups, so answer choice C is incorrect. Cyanogen bromide cleaves peptide bonds at the C-terminal side of methionine residues, not cysteine residues, so answer choice D is incorrect. Performic acid reacts with methionine residues, not cysteine residues, so answer choice E is incorrect.

Which of the Following Reagents Is Correctly Defined