TABLE 1.
Mechanical unfolding properties of different protein domains studied to date by AFM
| Protein | Construct | SCOP Class* | SCOP Fold* | Parallel terminal strands* | Force/pN (speed/nms−1)* | Reference |
|---|---|---|---|---|---|---|
| Calmodulin | (Cam)4 | all α | EF Hand-like | No | <15 (600) | (6) |
| Spectrin | (R16)4 | all α | Spectrin repeat-like | No | 60 and 80 (3000) | (7) |
| Barnase | (I27)5(Ba)3 | α+β | Microbial Ribonuclease | No | 70 (300) | (8) |
| Ubiquitin | (Ub)9 | α+β | β-grasp | Yes | 203 (400) | (3) |
| Ubiquitin | (Ub)8 | α+β | β-grasp | Yes | 230 (1000) | (17) |
| GFP | (Ig)4GFP(Ig)4 or (DdFLN)3GFP(DdFLN)2 | α+β | GFP-like | No | 104 (3000) | (4) |
| C2A | (C2A)9 | all β | Ferredoxin-like | No | 60 (600) | (6) |
| E2lip3 | (I27)4E2lip3 | all β | Barrel-sandwich like | No | <15 (600) | (15) |
| FLN4 | (I27–30)FLN4(I31–34) | all β | Immunoglobulin-like β-sandwich | Yes | 63 and 53 (250–350) | (18) |
| 1FNIII | (1FNIII-2FNIII)6 | all β | Immunoglobulin-like β-sandwich | Yes | 220 (600) | (13) |
| 10FNIII | (10FNIII)8 | all β | Immunoglobulin-like β-sandwich | Yes | 75 | (13) |
| 12FNIII | (12FNIII-13FNIII)5 | all β | Immunoglobulin-like β-sandwich | Yes | 125 | (13) |
| 13FNIII | (I27-13FNIII)8 | all β | Immunoglobulin-like β-sandwich | Yes | 89 | (13) |
| I1 | (I27-I1)4 | all β | Immunoglobulin-like β-sandwich | Yes | 127 (600) | (64) |
| I4 | (I4)8 | all β | Immunoglobulin-like β-sandwich | Yes | 171 | (12) |
| I5 | (I5)8 | all β | Immunoglobulin-like β-sandwich | Yes | 155 | (12) |
| I27 | (I27)8 | all β | Immunoglobulin-like β-sandwich | Yes | 180 | (37) |
| I27 | (I27)8 | all β | Immunoglobulin-like β-sandwich | Yes | 204 | (12) |
| I28 | (I28)8 | all β | Immunoglobulin-like β-sandwich | Yes | 257 | (12) |
| I32 | (I32)8 | all β | Immunoglobulin-like β-sandwich | Yes | 298 | (12) |
| 34 | (I34)8 | all β | Immunoglobulin-like β-sandwich | Yes | 281 | (12) |
The proteins included here all consist of tandem arrays (the C-terminus of one domain is linked to the N-terminus of the next), which include no more than two different protein domains or are such that the protein under study was unambiguously assigned and was mechanically unfolded numerous times at a defined speed to obtain reliable estimates for the measured unfolding forces. The fold classification is taken from SCOP (34). FLN4 is reported to unfold via an intermediate, and both forces are included.
*
In heteropolymers, the data relates to the domain named in the first column.