TABLE 2.

Summary of the hydrodynamic properties and structural features determined for MARS particles in solution or estimated from bead models representing the ab initio SAXS and EM three-dimensional reconstructions of MARS molecular envelope

M_r, molecular mass; Rh/R_g = hydrodynamic/gyration radius; f/f₀, frictional ratio; S, sedimentation coefficient; Sved, Svedberg units; Dmax, maximum particle size.

Experimental or predicted values from	Mr	Rh	f/f0	S	Rg	Dmax	Volume	Shape factorsa
								Rg/Rh	Smax/S
	MDa	Å		Sved	Å	Å	106 Å3
SDS-PAGE analysis + titrationb	∼1.51						∼1.82c		∼2.0
SEC-MALLS	1.59 ± 0.02	151 ± 11
DLS		147 ± 25						0.93–1.16
AUC	∼1.19 ± 0.1	123	1.8	21.81				1.13	1.85 ± 0.1
SAXS					139 ± 2	520 ± 25
Selected SAXS bead models		130–136		21–22f	138–141	490–520		1–1.1	1.9–2.0
EM volumes in negative staind		80		35f	67	218	1.5	0.84	1.2
EM volumes in vitreous iced		99		28f	74	271	1.6	0.75	1.4
Escherichia coli 50 S ribosomee	1.55	99		50f	73	271	1.7	0.74	1
E. coli 70 S ribosomee	2.5	117		66f	89	288	2.7	0.76	1

^a R_g/Rh is typically ∼0.77 and ∼1.4 for a globular and denatured protein, respectively (50), and S_max/S is in the ranges 1.2–1.3, 1.5–1.9, and 2.0–3.0 for globular, moderately elongated, and highly elongated proteins, respectively (47). R_g/Rh was determined using R_g obtained by SAXS or predicted from the bead models, and S_max/S was determined using S_max ∼ 0.00361(M_r)^2/3 (47), M_r ∼ 1.2 MDa for all bead models as in Wolfe et al. (29), and S was obtained by AUC or predicted from the bead models.

^b SDS-PAGE densitometric analysis combined with enzymatic titration.

^c Sum of the standard atomic volumes of each component according to Voss and Gerstein (46) (Table I).

^d Volumes were from EM images in negative stain and vitreous ice filtered to 30 and 36 Å, respectively, from Norcum and Boisset (27).

^e PDB code 2AW4 (50 S); PDB codes 2AW4 + 2AVY for 70 S.

^f Solution properties predicted from bead models or crystal structures with the program HYDROPRO (40).