Alternate Fates of Pyruvate

Pyruvate can be metabolized to products other than lactate.
A. Oxidative decarboxylation to acetyl CoA
Oxidative decarboxylation of pyruvate by the PDHC is an important pathway in tissues with a high oxidative capacity such as cardiac muscle (Fig. 1). PDHC irreversibly converts pyruvate, the end product of aerobic glycolysis, into acetyl CoA, a TCA cycle substrate  and the carbon source for fatty acid synthesis .

Figure 8.24 Summary of the metabolic fates of pyruvate. TPP = thiamine pyrophosphate. TCA = tricarboxylic acid; NAD(H) = nicotinamide adenine dinucleotide; CoA = coenzyme A; CO2 = carbon dioxide.
B. Carboxylation to oxaloacetate
Carboxylation of pyruvate to oxaloacetate by pyruvate carboxylase is a biotin-dependent reaction (see Fig. 1). This irreversible reaction is important because it replenishes the TCA cycle intermediate and provides substrate for gluconeogenesis .
C. Reduction to ethanol (microorganisms)
The reduction of pyruvate to ethanol occurs by the two reactions summarized in Figure 1. The decarboxylation of pyruvate to acetaldehyde by thiamine-requiring pyruvate decarboxylase occurs in yeast and certain other microorganisms but not in humans.