Table 4.
Conformations of the binding-site loop in streptavidin structures from this study and as deposited at the PDB
| Subunit | |||||||
| Structurea | A | B | C | D | Bound ligand | pH | Mutations |
| apo-SAm1 | Ob | O | O | O | — | 7.3 | E44V/S45T/V47R |
| SAm1•StrepII | O | O | O | O | Strep-tag II peptide | 6.9 | E44V/S45T/V47R |
| apo-SAm2 | O | O | O | O | — | 7.3 | E44I/S45G/V47R |
| SAm2•StrepII | O | O | O | O | Strep-tag II peptide | 7.5 | E44I/S45G/V47R |
| 1df8 | C | biotin | 4.5 | S45A | |||
| 1pts | C | D | FSHPQNT | na | |||
| 1rst | O | Strep-tag peptide | 7.0 | ||||
| 1rsu | O | Strep-tag II peptide | 7.0 | ||||
| 1sld | O | Cyclo-Ac-CHPQFC-NH2 | 7.5 | ||||
| 1sle | O | O | Ac-CHPQGPPC-NH2 | 5.0 | |||
| 1slf | C | C | 2 • (NH4)2SO4 | 5.6 | |||
| 1slg | O | O | Ac-FCHPQNT | 5.6 | |||
| 1sre | C | C | HABA | na | |||
| 1srf | C | C | 3-t-Butyl-HABA | na | |||
| 1srg | C | C | 3-Methyl-HABA | na | |||
| 1srh | C | C | 3`5`-Dimethoxy-HABA | na | |||
| 1sri | C | C | 3`5`-Dimethyl-HABA | na | |||
| 1srj | C | C | Naphtyl-HABA | na | |||
| 1stp | C | biotin | 7.8 | ||||
| 1str | O | O | Ac-CHPQNT-NH2 | 7.0 | |||
| 1sts | O | O | FCHPQNT-NH2 | 7.0 | |||
| 1swa | C | D(O) | D(O) | D(O) | — | 4.5 | |
| 1swb | C | D(O) | D(O) | D(O) | — | 7.5 | |
| 1swc | D(O) | O | D(O) | O | — | 4.5 | |
| 1swd | C | D(O) | D(O) | C | biotin | 4.5 | |
| 1swe | C | C | C | C | biotin | 4.5 | |
| 1swh | D | D | D(O) | D(O) | — | 4.5 | W79F |
| 1swj | D(O) | C | O | D(O) | — | 4.5 | W79F |
| 1swk | C | C | C | C | biotin | 4.5 | W79F |
| 1swl | C | D(O) | D | D | — | 7.0 | W108F |
| 1swn | C | D(O) | C | C | biotin | 7.0 | W108F |
| 1swo | C | D(O) | D(O) | D(O) | — | 7.5 | W120F |
| 1swp | C | C | C | C | biotin | 7.5 | W120F |
| 1swq | D | D(O) | D | D(O) | — | 7.5 | W120A |
| 1swr | C | C | C | C | biotin | 7.5 | W120A |
| 1sws | D(O) | O | D(O) | D(O) | — | 4.5 | D128A |
| 1swt | O | O | biotin | 4.5 | D128A | ||
| 1swu | C | D(O) | D(O) | D(O) | — | 4.5 | Y43F |
| 1vwa | O | O | FSHPQNT | 4.5 | |||
| 1vwb | O | Cyclo-Ac-CHPQFC-NH2 | 11.8 | ||||
| 1vwc | O | Cyclo-Ac-CHPQFC-NH2 | 2.0 | ||||
| 1vwd | O | Cyclo-Ac-CHPQFC-NH2 | 3.0 | ||||
| 1vwe | O | Cyclo-Ac-CHPQFC-NH2 | 3.6 | ||||
| 1vwf | O | Cyclo-Ac-CHPQGPPC-NH2 | 3.7 | ||||
| 1vwg | O | (Cyclo-Ac-CHPQGPPC-NH2)2 | 2.5 | ||||
| 1vwh | O | (Cyclo-Ac-CHPQGPPC-NH2)2 | 3.5 | ||||
| 1vwi | O | O | Cyclo-[5S-Valeramido-HPQGPPC]K-NH2 | 1.5 | |||
| 1vwj | O | O | Cyclo-[5S-Valeramido-HPQGPPC]K-NH2 | 2.5 | |||
| 1vwk | O | O | Cyclo-[5S-Valeramido-HPQGPPC]K-NH2 | 3.0 | |||
| 1vw1 | O | O | Cyclo-[5S-Valeramido-HPQGPPC]K-NH2 | 3.5 | |||
| 1vwm | O | Cyclo-Ac-CHPQFC-NH2 | 4.2 | ||||
| 1vwn | O | Cyclo-Ac-CHPQFC-NH2 | 4.8 | ||||
| 1vwo | O | Cyclo-Ac-CHPQGPPC-NH2 | 2.9 | ||||
| 1vwp | O | Cyclo-Ac-CHPQGPPC-NH2 | 2.5 | ||||
| 1vwq | O | Cyclo-[5S-Valeramido-HPQGPPC]K-NH2 | 2.5 | ||||
| 1vwr | O | Cyclo-[5S-Valeramido-HPQGPPC]K-NH2 | 3.5 | ||||
| 2iza | C | — | 2.0 | ||||
| 2izb | C | — | 3.1 | ||||
| 2izc | C | — | 2.0 | ||||
| 2izd | C | — | 3.0 | ||||
| 2ize | C | — | 3.1 | ||||
| 2izf | C | C | biotin | 4.0 | |||
| 2izg | C | C | biotin | 2.0 | |||
| 2izh | C | C | biotin | 10.4 | |||
| 2izi | C | C | biotin | 2.5 | |||
| 2izj | C | C | biotin | 3.5 | |||
| 2izk | C | C | glycoluril | 2.6 | |||
| 2izl | C | C | 2-iminobiotin | 7.3 | |||
| 2rta | C | C | — | 3.0 | |||
| 2rtb | C | C | — | 3.3 | |||
| 2rtc | C | C | — | 3.6 | |||
| 2rtd | C | C | biotin | 1.4 | |||
| 2rte | C | C | biotin | 1.9 | |||
| 2rtf | C | C | biotin | 2.0 | |||
| 2rtg | C | C | biotin | 2.4 | |||
| 2rth | C | C | glycoluril | 2.5 | |||
| 2rti | C | C | glycoluril | 2.5 | |||
| 2rtj | C | C | glycoluril | 2.5 | |||
| 2rtk | C | C | glycoluril | 2.6 | |||
| 2rtl | C | C | 2-iminobiotin-sulfate | 2.5 | |||
| 2rtm | C | C | 2-iminobiotin-sulfate | 3.5 | |||
| 2rtn | C | C | 2-iminobiotin | 2.0 | |||
| 2rto | C | C | 2-iminobiotin | 2.6 | |||
| 2rtp | C | C | 2-iminobiotin | 3.3 | |||
| 2rtq | C | C | 2-iminobiotin | 3.3 | |||
| 2rtr | C | C | 2-iminobiotin | 4.0 | |||
a For authors and references of the crystal structures, cf. the PDB deposition.
b O, `open' loop conformation; C, `closed' loop conformation; D, disordered loop conformation; D(O), disordered loop conformation, but positioning of neighboring residues indicates preference for the `open' loop conformation.