Molecular interaction studies revealed the bifunctional behavior of triheme cytochrome PpcA from Geobacter sulfurreducens toward the redox active analog of humic substances.

摘要: Abstract Humic substances (HS) constitute a significant fraction of natural organic matter in terrestrial and aquatic environments can act as terminal electron acceptors anaerobic microbial respiration. Geobacter sulfurreducens has remarkable respiratory versatility utilize the HS analog anthraquinone-2,6-disulfonate (AQDS) acceptor or its reduced form (AH 2 QDS) an donor. Previous studies set triheme cytochrome PpcA key component for respiration G. , but process is far from fully understood. In this work, NMR chemical shift perturbation measurements were used to map interaction region between AH QDS, measure their binding affinity. The results showed that QDS binds reversibly more solvent exposed edge heme IV. visible spectroscopies coupled redox determine thermodynamic parameters PpcA:quinol complex. higher reduction potential IV (− 127 mV) compared (− 184 mV) explains why transfer favorable case by quinol. clear evidence obtained formation complex PpcA, combined with fact protein also formed AQDS, revealed first time bifunctional behavior toward HS. Such might confer selective advantage which any state available environment metabolic needs.