Intact carbonic acid is a viable protonating agent for biological bases.

ABSTRACT: Carbonic acid H₂CO₃ (CA) is a key constituent of the universal CA/bicarbonate/CO₂ buffer maintaining the pH of both blood and the oceans. Here we demonstrate the ability of intact CA to quantitatively protonate bases with biologically-relevant pK_as and argue that CA has a previously unappreciated function as a major source of protons in blood plasma. We determine with high precision the temperature dependence of pK_a(CA), pK_a(T) = -373.604 + 16,500/T + 56.478 ln T. At physiological-like conditions pK_a(CA) = 3.45 (I = 0.15 M, 37 °C), making CA stronger than lactic acid. We further demonstrate experimentally that CA decomposition to H₂O and CO₂ does not impair its ability to act as an ordinary c

SUBMITTER: Aminov D 

PROVIDER: S-EPMC6800339 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature