Hello everyone. I'm reading articles to perform for the first time an internalization assay of membrane receptors with Sulfo-NHS-Biotin. I understand that for cleavage biotin it is necessary that glutathione (GSH) reduces the disulfide bridge present in Sulfo-NHS-Biotin.

My doubt is that in some articles they use reduced GSH and in others oxidized GSH, but I do not understand on the basis of which criteria I should use one or the other.

Thank you in advance,

Alejandro F.