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SW56 (60) rotor

Centrifugation

Density gradient centrifugation

Density gradient centrifugation

Volumes and concentrations for log-linear^* sucrose gradients

Calculations of Barbara-Ellen Jackson, Andrew O. Jackson and Myron K. Brakke as described in Analytical Biochemistry 38, 56-64 (1970)

For SW 65L Rotor (5.3ml gradients for 1/2 x 2 inch cellulose nitrate tubes using 0.2ml sample^a)

Pb 1.3	6oC		Pb 1.3	14oC		Pb 1.5	6oC		Pb 1.5	14oC
ml	mg/ml		ml	mg/ml		ml	mg/ml		ml	mg/ml
0..35	0		0.47	0		0.45	0		0.57	0
0.61	80		0.67	80		0.54	80		0.58	80
1.03	160		0.84	160		0.72	160		0.69	160
1.11	210		1.12	210		1.08	210		1.07	210
1.48	260		1.53	260		1.70	260		1.53	270
0.72	300		0.67	300		0.81	300		0.86	300

For SW 65L Rotor (5.05 ml gradients for 1/2 x 2 inch polyallomar tubes using 0.2ml sample^a)

Pb 1.3	6oC		Pb 1.3	14oC		Pb 1.5	6oC		Pb 1.5	14oC
ml	mg/ml		ml	mg/ml		ml	mg/ml		mg/ml	ml
0.46	0		0.56	0		0.53	0		0.58	0
0.60	80		0.63	80		0.52	80		0.58	80
0.86	160		0.81	160		0.73	160		0.73	160
1.04	210		1.11	210		1.02	210		1.02	210
1.49	260		1.44	260		1.58	260		1.49	260
0.60	300		0.50	300		0.67	300		0.65	300

^* For these gradients log of depth is a linear function of log of sedimentation coefficient, simplifying estimation of sedimentation coefficients. Layered gradients (dilute phosphate buffer) were stored at 2^oC for 15-16 hours. After layering samples, the centrifuge rotor was held at low speed until temperature stabilized. See original paper for further details.
^a Remove a volume equal to sample size from the top of the gradient shortly before floating samples on the gradients.
^b P_b is the buoyant density of the particle in sucrose and the temperature is that at which the gradient is centrifuged. P_b=1.3 is usually used for viruses and P_b=1.5 for RNA centrifugation