BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Events//NONSGML v1.0//EN
METHOD:PUBLISH
BEGIN:VEVENT
DTSTART;TZID="Pacific Time (US & Canada)":20261009T161000
DTEND;TZID="Pacific Time (US & Canada)":20261009T170000
SUMMARY:PChem Seminar – Min Wang
LOCATION:Fulmer Hall
DESCRIPTION:Speaker: Min Wang\n\nGroup: Dr. ChulHee Kang\n\nTitle: Interactions Between Sorghum Cytochrome P450 Isoenzymes and Their Reductases\n\nAbstract: Cinnamate 4-hydroxylase (C4H), a cytochrome P450 enzyme critical for lignin biosynthesis, relies on interprotein electron transfer from NADPH via CPR to activate molecular oxygen. Sorghum has three C4H and three CPR isoforms, yet the physical principles governing the coupling efficiency of each C4H–CPR pair remain unclear. Here, we combined structure prediction, X-ray crystallography, molecular docking simulations, electrostatic surface analysis, and steady-state kinetics to examine all nine pairs. Three-dimensional models were generated with AlphaFold 3, which pairs a Pairformer module that learns pairwise residue relationships with a diffusion model that generates atomic coordinates. Molecular docking simulations with interaction-energy decomposition showed that complex stability is dominated by electrostatic rather than van der Waals contributions. In one isoform, C4H3, a short insertion at the binding interface induces an ~11° rigid-body rotation of CPR. This rotation breaks two interfacial ion pairs and lowers the electrostatic energy per buried surface area by 27%. Electrostatic potential surfaces confirmed a smaller, fragmented electropositive patch on C4H3. Transition-state (Eyring) analysis of the kinetic data revealed a nearly constant activation free energy for turnover across all pairs. Together, these results indicate that interfacial electrostatics are necessary but not sufficient for efficient catalysis, and point to conformational dynamics and intramolecular electron transfer within CPR as a key determinant of catalytic efficiency.
BEGIN:VALARM
ACTION:DISPLAY
DESCRIPTION:REMINDER
TRIGGER;RELATED=START:-PT00H15M00S
END:VALARM
END:VEVENT
END:VCALENDAR