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Figure 5
Entrance-conduit water dynamics. (a) 15 atm CO2 hCA II, (b) 7.0 atm CO2 hCA II, (c) 2.5 atm CO2 hCA II, (d) 15 atm CO2 hCA II – 50s, (e) 15 atm CO2 hCA II – 1h. In all cases, the electron-density (2FoFc) maps are contoured at 1.3σ. The intermediate water WI is coloured light grey and the entrance-conduit waters are coloured cyan for clarity. Although all five WEC waters (WEC1, WEC2, WEC3, WEC4 and WEC5) exist in all of the structures regardless of the different internal CO2 pressures, dramatic variations of WEC1 (near to the proton-shuttling His64), WEC2 (near to WI, W′I and W1) and W3b′ are manifested by multiple alternate positions during the internal CO2 pressure decrease. These observations indicate that the waters of the proton-transfer network (W1/W2/W2′/W3a/W3b/W3b′), the intermediate waters (WI/W′I) and the entrance conduit waters (WEC1/WEC2/WEC3/WEC4/WEC5) all act interdependently and are dynamically correlated.

Volume 5| Part 1| January 2018| Pages 93-102
ISSN: 2052-2525