Carbamyl phosphate synthesis in invertebrates

Abstract

1.1. Carbamyl phosphate synthesis in mitochondria from land snail (Otala lactea and Helix aspersa) hepatopancreas, earthworm (Lumbricus terrestris) gut tissue and land planarian (Bipalium kewense) whole body is mediated, in part, by an enzyme that utilizes l-glutamine as a substrate and requires N-acetyl-l-glutamate as a cofactor. This glutamine enzyme was first described in hepato-pancreas of the snail Strophocheilus oblongus and now appears to be widely distributed among invertebrates.2.2. In addition to the glutamine enzyme, mitochondria from the earthworm and land planarian and possibly the snail Helix also possess an enzyme that utilizes ammonia in the presence of N-acetyl-l-glutamate and is therefore similar to carbamyl phosphate synthetase-I, the enzyme for arginine and urea biosynthesis in vertebrates.3.3. In all four species, the major site of carbamyl phosphate synthesis was in the mitochondrion and the major enzyme detected was the glutamine enzyme. In the earthworm, the amount of carbamyl phosphate synthetase-I was only slightly less than that of the glutamine enzyme and both enzymes were found in the soluble cellular fraction as well as in the mitochondrial fraction during localization studies.