TABLE 2.

Requirements for maltosyltransferase activity

Incubations mixtures	Radioactivity in methanol-insoluble product
	Crude extract (not dialyzed)	(NH4)2SO4 fraction (dialyzed)
	cpm
Completea	8200	9600
Heat-killed enzyme	1300	1200
Without glycogen	1100	1400
Plus 300 nm Pi	6000	6600
3 mm Pi	2000	2800
Plus 300 nm arsenate	4100	2900
3 mm arsenate	1500	1300
Plus 300 mm Glc-1-P	6300	8700
3 mm Glc-1-P	4900	7300
Plus 3 mm ATP	1000	1000

^a Complete reaction contained 150 μl of 50 mm Tris buffer, pH 7.0, 50 μl of glycogen (10 mg/ml), 25 μl of [¹⁴C]maltose-1-P (12.5 nmol, 125,000 cpm), enzyme (25–50 μg of protein), and other components as shown. Incubations were for 20 min and were stopped by placing tubes in a boiling water bath for 3 min. Then 900 μl of methanol were added, and tubes were vortexed vigorously and placed in a −20 °C freezer for 30 min. The precipitates were isolated by centrifugation, suspended in water, and subjected to scintillation counting.