Guanidine hydrochloride

A strong organic base existing primarily as guanidium ions at physiological pH. It is found in the urine as a normal product of protein metabolism. It is also used in laboratory research as a protein denaturant. (From Martindale, the Extra Pharmacopoeia, 30th ed and Merck Index, 12th ed) It is also used in the treatment of myasthenia and as a fluorescent probe in HPLC. (In Vitro) :Guanidine hydrochloride at low concentrations refolds acid-unfolded apomyoglobin and cytochrome c, stabilizing the molten globule state, i.e. a compact denatured state with a significant amount of secondary structure, but substantially disordered tertiary structure. Guanidine hydrochloride (> 1 M) causes co-operative unfolding of the molten globule state.A considerable degree of ordered structure remains due to the presence of disulfide bonds, which Guanidinehydrochloride does not affect.Guanidine hydrochloride at millimolar concentrations, is able to causes efficient loss of the normally stable [PSI+] element from yeast cells. 5 mM Guanidine hydrochloride in growth media cures [PSI+] and other prions of yeast. 5 mM Guanidine hydrochloride significantly reduces Hsp104-mediated basal and acquired thermotolerance by 30-fold and 50 fold, respectively. Guanidine hydrochloride also reduces the ability of Hsp104 to restore activity of thermally denatured luciferase. (In Vivo) :A significant reduction in the death rate of infant mice infected with ten LD50) of coxsackievirus A16 is observed when they are treated 58 h after infection with two injections of Guanidine hydrochloride at 145 mg/kg per injection.