New Insights into the Determinants of Specificity in Human Type I Arginase: Generation of a Mutant That Is Only Active with Agmatine as Substrate.

Arginase catalyzes the hydrolysis of L-arginine into L-ornithine and urea. This enzyme has several analogies with agmatinase, which catalyzes the hydrolysis of agmatine into putrescine and urea. However, this contrasts with the highlighted specificity that each one presents for their respective substrate.

Insights on the participation of Glu256 and Asp204 in the oligomeric structure and cooperative effects of human arginase type I.

Arginase (EC 3.5.3.

Functional analysis of the Mn requirement in the catalysis of ureohydrolases arginase and agmatinase - a historical perspective.

Ureohydrolases form a conserved family of enzymes with a strict requirement for divalent metal ions for catalytic activity. They catalyze the hydrolysis of the guanidino group and produce urea. In their active sites six highly conserved amino acid residues form a binding pocket for two catalytically essential metal ions that are needed to activate a water molecule to initiate the hydrolysis of the guanidino group in a nucleophilic attack.

Metabolic strategies for the degradation of the neuromodulator agmatine in mammals.

Agmatine (1-amino-4-guanidinobutane), a precursor for polyamine biosynthesis, has been identified as an important neuromodulator with anticonvulsant, antineurotoxic and antidepressant actions in the brain. In this context it has emerged as an important mediator of addiction/satiety pathways associated with alcohol misuse. Consequently, the regulation of the activity of key enzymes in agmatine metabolism is an attractive strategy to combat alcoholism and related addiction disorders.

Mammalian agmatinases constitute unusual members in the family of Mn-dependent ureahydrolases.

Agmatine (1-amino-4-guanidinobutane) plays an important role in a range of metabolic functions, in particular in the brain. Agmatinases (AGMs) are enzymes capable of converting agmatine to the polyamine putrescine and urea. AGMs belong to the family of Mn-dependent ureahydrolases.

Cloning of two LIMCH1 isoforms: characterization of their distribution in rat brain and their agmatinase activity.

Agmatine, a precursor for polyamine biosynthesis, is also associated with neurotransmitter, anticonvulsant, antineurotoxic and antidepressant actions in the brain. This molecule results from the decarboxylation of L-arginine by arginine decarboxylase, and it is hydrolyzed to urea and putrescine by agmatinase. Recently, we have described a new protein that also hydrolyzes agmatine, agmatinase-like protein (ALP), which was identified through immunohistochemical analysis in the hypothalamus and hippocampus of rats.

Insight on the interaction of an agmatinase-like protein with Mn(2+) activator ions.

Agmatinase is an enzyme that catalyzes the hydrolysis of agmatine, a compound that is associated with numerous functions in the brain of mammalian organisms such as neurotransmitter, anticonvulsant, antinociceptive, anxiolytic and antidepressant-like actions. To date the only characterized agmatinases with significant enzymatic activity were extracted from bacterial organisms. These agmatinases are closely related to another ureahydrolase, arginase; both have binuclear Mn(2+) centers in their active sites.

Mutagenic and kinetic support for an allosteric site in arginase from the extreme thermophile Bacillus caldovelox, which allows activation by arginine.

To substantiate the functionality of a crystallographically evidenced allosteric site in Bacillus caldovelox arginase (Bewley et al., 1999), we have examined the kinetic consequences of the single mutations of Asp199 and Glu256, which interact with l-arginine in this site. The introduced mutations (Asp199 → Asn, Asp199 → Ala, Glu256 → Gln and Glu256 → Ala) had no effect on the hexameric structure of the enzyme (mol.

Further insight into the inhibitory action of a LIM/double zinc-finger motif of an agmatinase-like protein.

Agmatine is a precursor for polyamine biosynthesis also associated to neurotransmitter, anticonvulsant, antineurotoxic and antidepressant actions in the brain. It results from decarboxylation of l-arginine by arginine decarboxylase and it is hydrolyzed to urea and putrescine by agmatinase. Recently, we have described a new protein which also hydrolyzes agmatine although its sequence greatly differs from all known agmatinases.

Evidence for an inhibitory LIM domain in a rat brain agmatinase-like protein.

We recently cloned a rat brain agmatinase-like protein (ALP) whose amino acid sequence greatly differs from other agmatinases and exhibits a LIM-like domain close to its carboxyl terminus. The protein was immunohistochemically detected in the hypothalamic region and hippocampal astrocytes and neurons. We now show that truncated species, lacking the LIM-type domain, retains the dimeric structure of the wild-type protein but exhibits a 10-fold increased k(cat), a 3-fold decreased K(m) value for agmatine and altered intrinsic tryptophan fluorescent properties.

Expression and localization of an agmatinase-like protein in the rat brain.

Agmatinase catalyzes the hydrolysis of agmatine into putrescine and urea, and agmatine (decarboxylated L: -arginine) plays several roles in mammalian tissues, including neurotransmitter/neuromodulatory actions in the brain. Injection of agmatine in animals produces anticonvulsant, antineurotoxic and antidepressant-like actions. Information regarding the enzymatic aspects of agmatine metabolism in mammals, especially related to its degradation, is relatively scarce.

Upregulation of arginase expression and activity in hypertensive rats exposed to chronic intermittent hypobaric hypoxia.

The aim of this study was to analyze the activity and expression levels of arginase I and II and to monitor the cardiovascular and hematological responses in tolerant and intolerant rats exposed to chronic intermittent hypobaric hypoxia (CIHH). Male Wistar rats (age: 3.0 +/- 0.

Glomerular diseases in a Hispanic population: review of a regional renal biopsy database.

Context And Objective: Epidemiological data provide useful information for clinical practice and investigations. This study aimed to determine glomerular disease frequencies in a region of Colombia and it represents the basis for future studies.

Design And Setting: Single-center retrospective analysis at the University of Antioquia, Colombia.

Studies on the functional significance of a C-terminal S-shaped motif in human arginase type I: essentiality for cooperative effects.

The functional significance of a C-terminal S-shaped motif (residues 304-322) in human arginase I was explored by examining the kinetic properties of the R308A mutant and truncated species terminating in either Arg-308 or Ala-308. Replacement of Arg-308 with alanine, with or without truncation, yielded monomeric species. All mutants were kinetically indistinguishable from the wild-type enzyme at the optimum pH of 9.

Cloning and functional expression of a rodent brain cDNA encoding a novel protein with agmatinase activity, but not belonging to the arginase family.

A rat brain cDNA encoding for a novel protein with agmatinase activity was cloned and functionally expressed. The protein was expressed as a histidine-tagged fusion product with a molecular weight of about 63 kDa. Agmatine hydrolysis was strictly dependent on Mn(2+); K(m) and k(cat) values were 2.

Mutational analysis of substrate recognition by human arginase type I--agmatinase activity of the N130D variant.

Upon mutation of Asn130 to aspartate, the catalytic activity of human arginase I was reduced to approximately 17% of wild-type activity, the Km value for arginine was increased approximately 9-fold, and the kcat/Km value was reduced approximately 50-fold. The kinetic properties were much less affected by replacement of Asn130 with glutamine. In contrast with the wild-type and N130Q enzymes, the N130D variant was active not only on arginine but also on its decarboxylated derivative, agmatine.

Insights into the interaction of human arginase II with substrate and manganese ions by site-directed mutagenesis and kinetic studies. Alteration of substrate specificity by replacement of Asn149 with Asp.

To examine the interaction of human arginase II (EC 3.5.3.

Kinetic studies and site-directed mutagenesis of Escherichia coli agmatinase. A role for Glu274 in binding and correct positioning of the substrate guanidinium group.

The interaction of Escherichia coli agmatinase (EC 3.5.3.

Non-chelating inhibition of the H101N variant of human liver arginase by EDTA.

Recombinant wild-type human liver arginase (EC 3.5.3.

Inactivation of human liver arginase by Woodward's reagent K: evidence for reaction with His141.

Human liver arginase (EC 3.5.3.

Studies on the interaction of Escherichia coli agmatinase with manganese ions: structural and kinetic studies of the H126N and H151N variants.

The H126N and H151N variants of Escherichia coli agmatinase (EC 3.5.3.

Insights into the reaction mechanism of Escherichia coli agmatinase by site-directed mutagenesis and molecular modelling.

Upon mutation of Asp153 by asparagine, the catalytic activity of agmatinase (agmatine ureohydrolase, EC 3.5.3.

Insights into the interaction of human liver arginase with tightly and weakly bound manganese ions by chemical modification and site-directed mutagenesis studies.

Diethyl pyrocarbonate (DEPC) caused a loss in the ability of inactive subunits of wild-type and H141F mutant human liver arginase (EC 3.5.3.