Table 1.
Reported ∆GU and Tm values for protein stability in the presence and absence of crowding agents are listed together with key properties (polypeptide length, fold, folded and unfolded state radius of gyration) of the proteins
| Name of the protein | Protein length (# of residues) | Protein fold (α, β, α/β) | Rg (nm)a | Thermal stability Tm (°C) | Chemical stability ∆GU (kJ/mol) | References | |||
|---|---|---|---|---|---|---|---|---|---|
| Unfolded | Folded | Buffer | Crowdingb | Buffer | Crowdingb | ||||
| D. desulfuricans apoflavodoxin | 148 | α/β | 4.0 | 1.7 | 48 (Hepes) | 64 (Hepes) 400 mg/ml Ficoll70 | 26.3 (phosphate) | 26.5 100 mg/ml Ficoll70 | (Stagg et al. 2007) |
| B. burgdorferi VlsE | 341 | α | 6.6 | 2.3 | 49 | 55 400 mg/ml Ficoll70 | 24 | 29 100 mg/ml Ficoll70 | (Perham et al. 2007) |
| Horse heart cytochrome c | 104 | α | 3.2 | 1.5 | 63 (1 M GuHCl) | 70 (1 M GuHCl) 400 mg/ml Ficoll70 | 45 | 45 200 mg/ml Ficoll70 | (Christiansen et al. 2010) |
| Human co-chaperonin 10 | 102 (heptamer) | β | 3.2c | 1.5c | 67 | 71 300 mg/ml Ficoll70 | 9 c | 12 c 300 mg/ml Ficoll 70 | (Aguilar et al. 2011) |
| phosphoglycerate kinase (PGK) | 415 | α | 7.4 | 2.5 | 39 | 40.5 200 mg/ml Ficoll70 | – | – | (Dhar et al. 2010) |
| A. aeolicus ribosomal protein S16 | 116 | α/β | 3.4 | 1.5 | – | – | 18 | 31 200 mg/ml dextran20 | (Mikaelsson et al. 2012) |
| Hen egg-white lysozyme | 129 | α/β | 3.6 | 1.6 | 56 (pH 2) | 59 (pH 2) 300 mg/ml dextran70 | – | – | (Sasahara et al. 2003) |
| Glutaredoxin 2 | 215 | α/β | 5.0 | 2.0 | – | – | 14.0 | 15.1 100 mg/ml dextran70 | (Kuhnert et al. 2008) |
| Human glutathione transferase A1-1 | 222 (dimer) | α | 5.1c | 2.0c | – | – | 24.0 | 26.2 100 mg/ml dextran70 | (Kuhnert et al. 2008) |
| A. vinelandii apoflavodoxin | 179 | α/β | 4.5 | 1.8 | 48.1 | 52.3 400 mg/ml dextran70 | – | – | (Engel et al. 2008) |
| Cellular retinoic acid-binding protein 1 | 137 | Mostly α | 3.8 | 1.6 | – | – | 35 | 33 150 mg/ml Ficoll70 | (Hong and Gierasch 2010) |
| E coli maltose binding protein | 370 | Mostly α | 6.9 | 2.4 | 62 | 63 300 mg/ml Ficoll70 | – | – | (Kulothungan et al. 2009) |
| Apocytochrome b562 | 106 | α | 3.2 | 1.5 | – | – | 12 | 13 85 mg/ml PEG20 | (Ai et al. 2006) |
| Human FK506-binding protein | 107 | α/β | 3.3 | 1.5 | – | – | 21.0 | 23.1 180 mg/ml Ficoll70 | (Spencer et al. 2005) |
| Deoxyribonuclease I (DNase I) | 282 | α/β | 5.9 | 2.2 | 60 | >80 200 mg/ml PEG4 | – | – | (Sasaki et al. 2007) |
| Skeletal muscle G-actin | 374 | α/β | 7.0 | 2.4 | 45 | 49 100 mg/ml PEG6 | – | – | (Tellam et al. 1983) |
In each case, the amount and kind of crowding agent used in the original study is given. If important, the solution conditions are also given. We note that data for only one crowded condition is listed for each protein; in most cases, several concentrations and types of crowding agents were tested. Rg values were estimated using chain-length correlations in (Millett et al. 2002)
aRadius of gyration (Rg) for unfolded and folded forms of the proteins were estimated using empirical chain length correlations reported in (Millett et al. 2002)
bFicoll70, 70 kDa; dextran70, 70 kDa; dextran20, 20 kDa; PEG4, 4 kDa; PEG6, 6 kDa; PEG20, 20 kDa
cValues for individual monomers