Arginase synthesis

Eliasson, E. 1967. Repression of arginase synthesis in Chang liver cells. Exp. Cell Res., 48 1. 

Changes in the concentration of arginine, via arginase activity, can play a role in regulating the rate of nitric oxide synthesis. Nitric oxide is a messenger molecule that has several roles. One is to increase the activity of the enzyme guanyl cyclase, which increases the concentration of cyclic GMP. The latter causes vasolidation in peripheral... 

Argininemia <0.5 Urea synthesis Arginase Mental retardation... 

The final step of the urea cycle is the cleavage of arginine to release urea and regenerate ornithine. Ornithine then reenters the mitochondria via the ORNT-1 ornithine-citrulline antiporter. ARG-1 is a cytosolic homotrimeric enzyme of 35-kd monomers that is expressed in fiver and red blood cells. A second mitochondrial arginase (ARG-2) most likely plays a role in nitric oxide synthesis and is most abundant in brain, kidney, and prostate. ARG-1 deficiency is unique among the urea cycle deficiencies as patients do not present with hyperammonemia and encephalopathy but rather develop progressive spasticity of the lower limbs. Biochem-... 

Arginine and fumarate are produced from argininosuccinate by the cytosolic enzyme argininosuccinate lyase. In the final step of the cycle arginase cleaves urea from aspartate, regenerating cytosolic ornithine, which can be transported to the mitochondrial matrix for another round of urea synthesis. 

The precursor for polyamine synthesis in mammalian cells as well as in P. falciparum is arginine, which is converted by arginase to urea and ornithine (Muller et ah, 2005) the latter is subsequently decarboxylated by ODC to PU. However, there is evidence for an alternative pathway in the related apicomplexan Cryptosporidium, where arginine is decarboxylated to agmatine and subsequently converted to PU (Keithly et ah, 1997). Thereafter in mammals SPD and SM are formed by the catalytic action of SPD synthase and SM synthase. AdoMetDC and ODC are the rate-limiting enzymes for polyamine synthesis. 

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