The missing hydrogen ion, part-2: Where the evidence leads to

The purpose of this manuscript was to present the evidence for why cells do not produce metabolic acids. In addition, evidence that opposes common viewpoints and arguments used to support the cellular production of lactic acid (HLa) or liver keto-acids have been provided. Organic chemistry reveals that many molecules involved in cellular energy catabolism contain functional groups classified as acids. The two main acidic functional groups of these molecules susceptible to ∼H⁺ release are the carboxyl and phosphoryl structures, though the biochemistry and organic chemistry of molecules having these structures reveal they are produced in a non-acidic ionic (negatively charged) structure, thereby preventing pH dependent ∼H⁺ release. Added evidence from the industrial production of HLa further reveals that lactate (La^-) is produced followed by an acidification step that converts La^- to HLa due to pH dependent ∼H⁺ association. Interestingly, there is a plentiful list of other molecules that are classified as acids and compared to HLa have similar values for their H⁺ dissociation constant (pK_d). For many metabolic conditions, the cumulative turnover of these molecules is far higher than for La^-. The collective evidence documents the non-empirical basis for the construct of the cellular production of HLa, or any other metabolic acid.