Abstract

Optimizing the efficiency of oxygenic photosynthesis is critical for global food security and bioenergy production. A key regulatory mechanism involves the pH gradient across the thylakoid membrane, which controls the rate of photosynthetic electron transport (PET). This study presents an *in silico* model to investigate the complex, non-linear relationship between thylakoid lumen pH and the overall efficiency of PET in chloroplasts. The model integrates kinetic parameters of the cytochrome $b_6f$ complex and the ATP synthase, which are highly sensitive to proton concentration. Our simulations reveal that fine-tuning the pH-dependent regulatory loops can significantly enhance the steady-state rate of electron flow, particularly under fluctuating light conditions. Specifically, the model predicts an optimal lumen pH range that maximizes ATP and NADPH production while minimizing photoinhibition. These findings provide a theoretical framework for understanding the dynamic regulation of energy conversion in the thylakoid membrane and offer new targets for genetic engineering to improve photosynthetic performance in crops.