Table 3. Properties of useful sulfhydryl reducing agents

Table

Sulfhydryl reagent	Molecular weight	Density of liquid^a	Molarity of liquid^a	Comments
2-Mercaptoethanol^b	78	1.117 g/mL	14.3 M	Volatile
Thioglycerol	108	1.295 g/mL	12 M
Dithiothreitol or dithioerythreitol	154	Solid		Strong reducing agents
2,3-Dimercapto-propanol	124	1.239 g/mL	10 M	Moderately soluble in H₂O
Tributylphosphine^b	203	0.81 g/mL		Slightly soluble in H₂O
tris(2-carboxyethyl) phosphine (TCEP)				Soluble in H₂O; strong reductant over a wide pH range (1.5-8.5); stronger reductant than DTT at pH values <8.0. (Han and Han 1994)
L-cysteine	121	Solid
Thioglycolic acid	92	Solid
Glutathione (reduced)	307	Solid

^aData from Kohn et al. (1983).
^bBecause of high toxicity and offensive odors, use in a chemical fume hood.