TABLE 2.

Buffers for solubilization of recombinant E. coli cell extracts for GT MG517 purification

Buffer	Total proteina	Specific activityb
	mg/ml	units/mg
Buffer A: glycerol (20%) in 0.5 m NaCl, 50 mm phosphate, pH 7	4.1	0.083
Buffer B: Triton X-100 (0.5%) + glycerol (5%) in 0.5 m NaCl, 50 mm phosphate, pH 7	6.3	0.17
Buffer C: CHAPS (20 mm) in 0.5 m NaCl, 20 mm HEPES, pH 8	4.8	0.076
Buffer D: CHAPS (20 mm) + glycerol (10%) in 0.5 m NaCl, 20 mm HEPES, pH 8	7.0	0.24

^a Total protein in the soluble fraction after extraction, expressed as mg of protein/ml of cell extract.

^b Specific activity of the solubilized protein extract determined by the radiometric assay. Conditions were as follows: 1 mm UDPGal, 1.25 mm DOG, 20 mm HEPES, 20 mm MgCl₂, 20 mm CHAPS, 12.5 mm DOPG, pH 8.0, 35 °C. Units/mg, μmol of [¹⁴C]Gal incorporated/min/mg of total protein.