Conversion of Arginine to Proline in the Chick

Abstract

Studies were conducted to determine whether the conversion of arginine to proline may occur in the young chick. Feeding a diet devoid of proline resulted in a growth depression which could not be relieved by dietary supplements of arginine or ornithine. In two experiments using arginine-5-³H, however, it was found that chicks which were fed the proline-free diet converted a portion of the dietary arginine directly to proline. Approximately 7% of the arginine from the basal diet containing 1.0% arginine was converted to proline by chicks fed the proline-free diet. This represented on a molar basis most of the arginine which was catabolized, as estimated from urea excretion. It is concluded that the chick can convert arginine directly to proline, but that the amount of proline synthesized in this manner represents but a small part of the total amount of proline needed for growth.