The influence of disulfide bonds in proteins on the determination of sulfide.

Acid-labile sulfide content of proteins can be determined spectrophotometrically by procedures leading to the formation of methylene blue. A method has been proposed (involving addition of sulfide) to take into account absorption of dye by samples, but it has been found that recovery of sulfide is influenced by disulfide bonds, resulting in non-linear responses. A simplified procedure has been used to determine acid-labile sulfide in mitochondria from chicken liver and kidney, and linear responses to the amount of protein have been obtained.