Table 2.
Binding of pectin molecules to PME
| Subsites | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| −5 | −4 | −3 | −2 | −1 | +1 | +2 | +3 | +4 | +5 | |
| Preference | C | C | M | X | M | |||||
| Substrate I | M | M | C | C | C | M | ||||
| Substrate II | C | C | M | M | M | C | ||||
| Substrate III | M | C | C | C | C | M | ||||
| Substrate IV | C | M | M | M | M | C | ||||
| Product | C | C | C | C | C | C | ||||
| PH 6.5 | M | C | C | C | C | X | ||||
| PH 3.2 | X | M | C | C | C | C | ||||
| GalA residues in bold and italics were visible at 1.5 and 0.5 σ, respectively in σA-weighted 2Fobs–Fcalc syntheses. C indicates GalA, M indicates methylated GalA and X indicates the residue could be GalA or methylated GalA. The row labelled ‘preference' gives the subsite preferences deduced from the structures of PME in complex with substrates I–IV. | ||||||||||