Proline is a nutritionally dispensable (non-essential) amino acid. Its synthesis and catabolism is via the pathway of ornithine and glutamate. The latter two amino acids serve as immediate precursors for proline, as well as metabolites. Ornithine is one of the intermediates for urea cycle. Glutamate is metabolically connected to tricarboxylic acid (TCA) cycle, the major cycle for energy production.
It is hypothesized that the significantly increased rates of net nitrogen loss and energy "production", as the consequence of the accelerated activities of both the urea and TCA cycles in burn injury "drain" both ornithine and glutamate, thus depleting tissues of the availability of proline. Hence, the de novo synthesis of proline is likely to be affected by the reduced availability of its major precursors: glutamate and ornithine. We further propose that increased supply of glutamine would increase the de novo synthesis of proline and / or spare the loss of proline via its metabolite glutamate. Hence, glutamine will be beneficial to the overall nutritional status of the burn patients.
