Size and Shape of Protein Molecules at the Nanometer Level Determined by Sedimentation, Gel Filtration, and Electron Microscopy

Table 5 Standards for hydrodynamic analysis

Protein	M _raa seq	S _20,w	S _max/S	R _s(nm)	Source	M _rS-M
Ribonuclease A beef pancreas	14,044	2.0^a	1.05^a	1.64	HBC	13,791
Chymotrypsinogen A beef pancreas	25,665	2.6	1.21	2.09	HBC	22,849
Ovalbumin hen egg	42,910s	3.5	1.27	3.05	HBC	44,888
Albumin beef serum	69,322	4.6^a	1.33	3.55	S-M, HBC	68,667
Aldolase rabbit muscle	157,368	7.3	1.45	4.81	HBC	147,650
Catalase beef liver	239,656	11.3	1.21	5.2	S-M	247,085
Apo-ferritin horse spleen	489,324	17.6	1.28	6.1	HBC	451,449
Thyroglobulin bovine	606,444	19	1.37	8.5	HBC	679,107
Fibrinogen, human	387,344	7.9	2.44	10.7	S-M	355,449

Gel filtration calibration kits, containing globular proteins of known molecular weight and R _s, are commercially available (GE Healthcare, Sigma-Aldrich). These same proteins can be used for sedimentation standards. The proteins in these kits are included in the table along with some others that we have found useful. The values for M _r given in the first column are from amino acid sequence data. Values for S _20,w and R _s are from the Siegel–Monte paper (indicated S-M under source), or the CRC Handbook of Biochemistry [3] (indicated HBC). They agree with the values listed for R _s in the GE Healthcare gel filtration calibration kit, with the exception of ferritin. The "M _r calc" in the last column was obtained by our simplification of the Siegel–Monte calculation (M = 4,205 S R _s). Note that the worst disagreement with "M _r aa seq" is about 10%
^a S for ribonuclease A is questionable because of the low S _max/S (1.05). S values for bovine serum albumin vary in the literature from 4.3 to 4.9. Many sources use 4.3, but we find that 4.6 gives a better fit with other standards (note that the standard curve in Figure 5 used 4.3, but 4.6 would have placed it closer to the line)

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