2.4.3. Disulfide bond content
Disulfide bond content in NAMwas determined using 2-nitro-5-
thiosulfobenzoate (NTSB) assay according to the method of
Thannhauser, Konishi, and Scheraga (1987). To 0.2 ml of NAM
sample (4 mg/ml), 3.0 ml of freshly prepared NTSB assay solution
was added. The mixture was incubated in the dark at room
temperature (25–27 C) for 25 min. Absorbance at 412 nm was
measured. Disulfide bond content was calculated using the
extinction coefficient of 13,900 M1 cm1.