What are the energetics of protein digestion during which the enzyme pepsin is "activated" (whatever that means) by HCl? I've looked and been unable to find anything like a chemical equation that includes an energy term.
Of course, pepsin, being an enzyme, is not used up in that sought-for equation. Is HCl used up? If so, what are the products? How and in what form is the chlorine removed, assuming the HCl is consumed in the equation?