Arginine degradation by arginase in mitochondria of soybean seedling cotyledons.

摘要: Arginase (EC 3.5.3.1) localization was studied in soybean (Glycine max L.) seedling cotyledons. Subcellular fractionation a discontinuous Percoll gradient showed that arginase localized the mitochondrion. Arginine (Arg) uptake by mitochondria demonstrated co-sedimentation of [3H]Arg-derived label and mitochondrial marker enzyme cytochrome c oxidase. complete about 10 min. Since detergent but not NaCl released most label, we conclude Arg taken up bound to organellar surface. transport saturable, at least 20 mM. Basic amino acids were best inhibitors uptake. The uncoupler 2,4-dinitrophenol did inhibit At 30% l-[guanido-14C]Arg degraded cotyledons, while little or no degradation detected from developing embryos, even though level similar both preparations. These results are consistent with our previously reported pattern expression urea accumulation during embryo development seed germination (A. Goldraij J.C. Polacco, 1999, Plant Physiol. 119: 297–303). lack allows embryos conserve Arg, main N-reserve acid utilized germinating soybean.