bilateral temporo-occipital hyperintensity on MRI (Fig. 1A, B). Thereafter, she acutely developed consciousness disturbance, showing elevation of plasma levels of ammonia, citrulline and arginine, and extensive brain edema (Fig. 1C, D). The liver biopsy revealed a selective decrease of argininosuccinate synthetase, leading to the diagnosis of adult-onset type II citrullinemia (CTLN2). Two month...

BACKGROUND Gene expression analysis in Leishmania donovani (Ld) identified an orthologue of the urea cycle enzyme, argininosuccinate synthase (LdASS), that was more abundantly expressed in amastigotes than in promastigotes. In order to characterize in detail this newly identified protein in Leishmania, we determined its enzymatic activity, subcellular localization in the parasite and affect on ...

The urea cycle converts ammonia, a waste product of protein catabolism, into urea. Because fish dispose ammonia directly into water, the role of the urea cycle in fish remains unknown. Six enzymes, N-acetylglutamate synthase (NAGS), carbamylphosphate synthetase III, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase and arginase 1, and two membrane transporters, orn...

The enzyme argininosuccinate synthetase (ASS) is the rate limiting enzyme in the metabolic pathway leading from L-citrulline to L-arginine, the physiological substrate of all isoforms of nitric oxide synthases (NOS). ASS and inducible NOS (iNOS) expression in neurons and glia was investigated by immunohistochemistry in brains of Alzheimer disease (AD) patients and nondemented, age-matched contr...

Nitric oxide (NO) acts as an endogenous mediator in mature skeletal muscle. In this study, we investigated the regulation of the endothelial (eNOS) and neuronal (nNOS) isoforms of nitric oxide synthase (NOS) in skeletal-muscle development (rat diaphragm). Muscle NOS activity, nNOS and eNOS protein, and mRNA expressions were markedly increased during the late gestational and early postnatal peri...

It has been previously demonstrated that the hepatic level of each enzyme concerned with the biosynthesis of urea in the rat, i.e. carbamyl phosphate synthetase, ornithine transcarbamylase, argininosuccinate synthetase, argininosuccinase, and arginase (see Ratner (1) and Cohen and Brown (2) for discussions of the enzymatic steps of urea biosynthesis and general problems of urea synthesis), bear...

The mechanism of the argininosuccinate lyase reaction has been probed by the measurement of the effects of isotopic substitution at the reaction centers. A primary deuterium isotope effect of 1.0 on both V and V/K is obtained with (2S,3R)-argininosuccinate-3-d, while a primary 15N isotope effect on V/K of 0.9964 +/- 0.0003 is observed. The 15N isotope effect on the equilibrium constant is 1.018...

Human somatic cell variants resistant to the arginine analog, canavanine, express 200-fold increased levels of argininosuccinate synthetase (AS) mRNA as compared to parental cells. In this study we examined whether AS cDNA sequences contain cis-acting regulatory elements that are involved in the induction of AS mRNA in canavanine-resistant cells. Minigene constructs containing AS cDNA sequences...