Table 1.

Mean values and standard deviations of Gaussian fits of the size distributions in Figure 3 and comparison of the full molecule length distribution to the sum of two long lobe dimension distributions. Lobe dimensions fit well within the maximum and minimum dimensions that can be measured from the respective crystallographic models (maximum dimension holo = 6.5 nm and apo = 6.8 nm; minimum dimension holo = 4.1 nm and apo = 4.8 nm). The comparison of the experimentally measured full molecule length and the sum of the lobe dimensions indicates a broadening of the full molecule length distribution which is in agreement with the observed elongation of the experimentally observed molecules with respect to the crystallographic models, which yield the following projected full-length dimensions: 9.5 nm for holo- and 10.5 nm for apo-transferrin.

	Lobe long dimension (nm)		Lobe short dimension (nm)		Full molecule length       (nm)		Sum of lobe long dim. (nm)
	Holo	Apo	Holo	Apo	Holo	Apo	Holo	Apo
Mean value ($\mu$)	5.1	5.8	4.3	5.0	11.5	12.4	10.2	11.6
Standard deviation ($\sigma$)	0.8	1.1	0.7	0.8	2.4	2.5	1.1	1.6