Glutamic acid, liberation from proteins

The mechanisms for the nonenzymatic formation of PQQ or any of its isomers are by no means obvious. These reactions must proceed from tyrosine, or partially oxidized tyrosines, and glutamic add or glutamine liberated from proteins. From tyrosine and glutamic acid, a ring alkylation and two successive ring closures are required together with a net 12-electron oxidation. 

Figure 5. Liberation of glutamic acid from serum proteins at 105°C. in 0.03N HCl...

An adapted soil bacterium identified as an Arthrobacter sp. incorporated most of the labeled carbon from dalapon-2-14C into various cellular components (amino acids, lipids, protein, and nucleic acids) while the carboxy carbon was accounted for mostly as 14C02 (2). Products identified on paper chromatograms were the amino acids alanine and glutamic acid (Figure 8). An enzyme preparation obtained from the supernatant fluid of broken cells of the same Arthrobacter sp. liberated Cl ion from dalapon to yield the organic acid pyruvate (31). The... 

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