Figure 5.

Schematic representation of interaction between NADPH oxidase and granule proteases. Electron transport through flavocytochrome b₅₅₈ consumes protons in the vacuole, elevating pH to a level optimal for neutral proteases, which are also activated by K⁺ driven into the vacuole to compensate the charge across the membrane. The hypertonic K⁺ solubilizes the cationic granule proteases and peptides by displacing them from the anionic sulphated proteoglycan granule matrix. The requirement for an alkaline, hypertonic environment restricts the toxicity of these proteins to the vacuolar compartment, thereby limiting damage to normal tissues.