Guanidine hydrochloride has commonly been used for the isolation of RNA, to denature globular proteins and for protein refolding studies. It can also be used to facilitate the generation of tryptic peptides for analysis of complex protein samples.

Guanidine Thiocyanate has commonly been used for the isolation of RNA, to denature globular proteins and for protein refolding studies. It can also be used to facilitate the generation of tryptic peptides for analysis of complex protein samples.