Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.5.1.4 (deaminase)
5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Autolysin-defective pneumococci continue to synthesize both peptidoglycan and teichoic acid polymers (Fischer and Tomasz, J. Bacteriol. 157:507-513, 1984). Most of these peptidoglycan polymers are released into the surrounding medium, and a smaller portion becomes attached to the preexisting cell wall. We report here studies on the degree of cross-linking, teichoic acid substitution, and chemical composition of these peptidoglycan polymers and compare them with normal cell walls. peptidoglycan chains released from the penicillin-treated pneumococci contained no attached teichoic acids. The released peptidoglycan was hydrolyzed by M1 muramidase; over 90% of this material adsorbed to vancomycin-Sepharose and behaved like disaccharide-peptide monomers during chromatography, indicating that the released peptidoglycan contained un-cross-linked stem peptides, most of which carried the carboxy-terminal D-alanyl-D-alanine. The N-terminal residue of the released peptidoglycan was alanine, with only a minor contribution from lysine. In addition to the usual stem peptide components of pneumococcal cell walls (alanine, lysine, and glutamic acid), chemical analysis revealed the presence of significant amounts of serine, aspartate, and glycine and a high amount of alanine and glutamate as well. We suggest that these latter amino acids and the excess alanine and glutamate are present as interpeptide bridges. Heterogeneity of these was suggested by the observation that digestion of the released peptidoglycan with the pneumococcal murein hydrolase (amidase) produced peptides that were resolved by ion-exchange chromatography into two distinct peaks; the more highly mobile of these was enriched with glycine and aspartate. The peptidoglycan chains that became attached to the preexisting cell wall in the presence of penicillin contained fewer peptide cross-links and proportionally fewer attached teichoic acids than did their normal counterparts. The normal cell wall was heavily cross-linked, and the cross-linked peptides were distributed equally between the teichoic acid-linked and teichoic acid-free fragments.
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PMID:Peptidoglycan cross-linking and teichoic acid attachment in Streptococcus pneumoniae. 400 47

Formiminotransferase-cyclodeaminase, a circular tetramer of dimers, binds four tetrahydropteroylpolyglutamates/octamer, which indicates that these polyglutamate sites are formed by one type of subunit interface. The transferase and deaminase are separate catalytic sites as determined by inhibition studies with (6R)-tetrahydropteroylglutamate and by the observation that the activities can operate simultaneously. Under conditions where the transferase is saturated with tetrahydropteroyl(glutamate)n substrate, exogenously added formimino intermediate is utilized by the deaminase only if at least one of the substrate/intermediate pair is a monoglutamate. These properties indicate the existence of only one polyglutamate site/pair of catalytic sites. Kinetic specificity for each activity as measured by Vm/Km increases for longer polyglutamates, but does not differentiate among 4, 5, 6, and 7 glutamates. The enzyme shows distinct preference for hexaglutamate based on Kd as well as on Km values. With all substrates, Vm of the deaminase is greater than that of the transferase, allowing for potential channeling of the intermediate between active sites. Efficiency of channeling, optimal with pentaglutamate, does not correspond with affinity for binding. This demonstrates that a steric requirement predominates over simple sequestering of intermediates on the enzyme surface as the fundamental mechanism for channeling.
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PMID:Channeling between the active sites of formiminotransferase-cyclodeaminase. Binding and kinetic studies. 406 60

Rats given a lethal dose (LD(99.9)) of ammonium acetate (10.8 mmol/kg of body weight) were protected to the extent of 85 and 76% when previously injected with N-carbamoyl glutamate or L-arginine, respectively, at a level of 4 mmol/kg of body weight. At a dose of 1 mmol/kg of body weight, L-arginine protected 24%, while N-carbamoyl-L-glutamate protected 61% of the animals. When a combination of N-carbamoyl-L-glutamate plus L-arginine (1 mmol each per kg of body weight) was injected, 100% of the rats were protected. The efficacy of N-carbamoyl-L-glutamate is related to its role as an activator of mitochondrial carbamoyl phosphate synthetase (EC 2.7.2.5) and its resistance to hydrolysis by tissue acylaminoacid acylase. N-Acetyl-L-glutamate, the naturally occurring and most effective activator of mitochondrial carbamoyl phosphate synthetase, was relatively ineffective in protection against lethal dose of ammonium acetate, because of its ready hydrolysis by acylaminoacid acylase. The findings reported provide a rational basis for the use of N-carbamoyl-L-glutamate plus L-arginine in the prevention and treatment of hyperammonemia in clinical conditions of liver disease and parental infusion of amino acids, and in feeding of urea supplements to ruminants.
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PMID:Ammonia intoxication in rats: protection by N-carbamoyl-L-glutamate plus L-arginine. 450 11

During growth of Aspergillus nidulans in medium containing ammonium the specific activities of most enzymes involved in catabolism of nitrogen sources are low (ammonium repression). The gdhA10 lesion, which results in loss of nicotinamide adenine dinucleotide phosphate-linked glutamate dehydrogenase activity, has been shown to lead to partial relief of ammonium repression of three amidase enzymes as well as histidase. The areA102 lesion led to altered levels of these enzymes but did not greatly affect ammonium repression. The double mutant areA102,gdhA10 was almost completely insensitive to ammonium repression of two of the amidase enzymes and histidase. This suggests that an interaction between the areA and gdhA genes in determining responses to ammonium occurs. Growth of mycelium in medium containing l-glutamate has been found to result in lowered levels of all four enzymes, and this occurs in strains insensitive to ammonium repression. Very strong repression in all strains occurred during growth in medium containing l-glutamine. Relief of these repressive effects of glutamate and glutamine was blocked by cycloheximide. Glutamate and glutamine had similar effects on the production of extracellular protease activity, and growth on glutamine led to low levels of urate oxidase. In contrast to the above enzymes, nitrate reductase was insensitive to the effects of glutamine and glutamate, even though this enzyme is very sensitive to ammonium repression. Although other possibilities exist, it is suggested that there may be mechanisms of general control of nitrogen-catabolic enzymes other than ammonium repression.
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PMID:Effects of ammonium, L-glutamate, and L-glutamine on nitrogen catabolism in Aspergillus nidulans. 461 4

Effects in vitro of glutamate, aspartate, fumarate and malate on substrate activation kinetics of AMP-deaminase in denervated and contralateral gastrocnemius muscles of the frog, Rana hexadactyla were studied. Glutamate increase the enzyme activity of both muscles by increasing maximal velocity (V) and decreasing Michaelis-Menten constant (Km), whereas, aspartate did not show any significant effect. Fumarate and malate exerted mixed type of inhibition by decreasing V and increasing Km of enzymes in both muscle preparations. The inhibitor constant (Ki) values suggest that the denervated muscle enzyme was more sensitive to fumarate and malate as compared to the contralateral muscle enzyme.
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PMID:Effects of some metabolic intermediates on AMP-deaminase activity in denervation atrophy. 618 33

The naturally occurring pteroylpolyglutamate derivatives are substrates for the folate-mediated reactions in cells, including the reactions catalyzed by two multifunctional folate dependent enzymes in eucaryotes. The appropriate derivatives of tetrahydropteroyl (glutamate)n where n = 1, 3, 5, or 7 were used to determine the specificity for, and kinetic advantages of the extra glutamyl residues with two multifunctional proteins from pig liver: methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase-formyltetrahydrofolate synthetase, and formiminotransferase-formininotetrahydrofolate cyclodeaminase. Specificity for the polyglutamate derivatives ranged from 10- to 70-fold as indicated from Km values or from the ability to inhibit the five different enzyme activities. With the sequential activities of the transferase-deaminase enzyme, it was demonstrated that when the tetrahydropteroyl pentaglutamate is used as a substrate, the intermediate formimino-compound does not accumulate in the medium. That this kinetic observation is due to preferential transfer of the pentaglutamate- but not monoglutamate intermediate from transferase to deaminase sites without its release from the enzyme molecule was supported by three types of experiments. Chemical modification to yield monofunctional derivatives of the transferase-deaminase affected the kinetics of the recombined activities only with the pentaglutamate substrate, causing a lag in the appearance of final product. Inhibition studies demonstrated that the deaminase activity could preferentially be inhibited only with the monoglutamate substrate. The deaminase activity with the monoglutamate substrate was increased by providing elevated formiminotetrahydrofolate in the assay mixture; no effect was observed when the reaction was carried out with pentaglutamate. Preliminary binding studies indicate a single folate site per subunit of the octameric enzyme, suggesting a type of combined transferase-deaminase site.
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PMID:Interaction of tetrahydropteroylpolyglutamates with two folate-dependent multifunctional enzymes. 641 22

An enzyme responsible for the deacylation of beta-citryl-L-glutamate to citrate and glutamate has been characterized in rat testis. The enzyme required manganese ion for full activity and was strongly inhibited by nucleotides such as ATP or GTP. The activity was localized in the particulate fractions. The enzyme favored N-formyl-L-glutamate greater than beta-citrly-L-glutamate greater than beta-citryl-L-glutamine in a decreasing order. The amidohydrolyase activity was highest in the testis and lung, a moderate activity was detected in heart, kidney and intestine, and low in brain, thymus, stomach, skeletal muscle, spleen and liver. These findings suggest that the amidohydrolase is different from any of amidohydrolases reported so far, amidohydrolase I (EC 3.5.1.14), II (EC 3.5.1.15), III, N-acetyl-lysine deacylase (EC 3.5.1.17) and N-acetyl-beta-alanine deacetylase (EC 3.5.1.21), and various peptidases.
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PMID:A beta-citryl-L-glutamate-hydrolysing enzyme in rat testes. 641 21

Concentrations of key metabolites were determined in goldfish red muscle, while muscle and blood before and after direct electrical stimulation of the myotome (60 pulses/min, amplitude 500 mV, 10 msec pulse duration, during 10 min at 20 degrees C). In white muscle, levels of ATP, aspartate and adenylate energy charge are significantly lowered while those of AMP, IMP, NH3, alpha-ketoglutarate, lactate and malate are increased. In red muscle, the only change induced by stimulation is a 160% increase of the lactate level. In white muscle, IMP-accumulation and ammonia production are equal, suggesting the AMP-deaminase reaction to be the major source of muscular ammonia. Activation of white muscle adenylosuccinate synthetase and adenylosuccinase is suggested by the conversion of aspartate into malate during increased energy demand. There is no evidence of ammonia incorporation into alanine, glutamate or glutamine.
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PMID:Goldfish muscle energy metabolism during electrical stimulation. 661 58

Rhodopseudomonas acidophila strain 7050 achieved balance growth when provided with either asparagine or glutamine as nitrogen source. Under these growth conditions R. acidophila synthesized a mixed amidase which exhibited similar activity (223--422 nmol/min . mg protein) against either nitrogen source. Determination of the free intracellular amino acid pools show that deamidation of asparagine and glutamine resulted in elevated levels of both aspartate and glutamate. Cell-free extracts of R. acidophila showed significant aminotransferase activity, particularly glutamine-oxaloacetate aminotransferase (89.7--209.3 nmol/min . mg protein), glycine oxaloacetate aminotransferase (135--227 nmol/min . mg protein), alanine glyoxylate aminotransferase (66.3--163.2 nmol/min . mg protein) and serine-glyoxylate aminotransferase (57.1--68.4 nmol/min . mg protein). Short term labelling experiments using 14C-glyoxylate show that glycine plays an important role in amino nitrogen transfer in R. acidophila and that the enzymes for the metabolism of glyoxylate via glycine, serine and hydroxypyruvate were present in cell-free extracts. These data confirm that R. acidophila can satisfy all its' nitrogen requirements by transamination.
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PMID:Asparagine and glutamine metabolism in Rhodopseudomonas acidophila. 721 28

The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. Tertiary destabilizing N-terminal residues asparagine and glutamine function through their conversion, by enzymatic deamidation, into the secondary destabilizing residues aspartate and glutamate, whose activity requires their enzymatic conjugation to arginine, one of the primary destabilizing residues. We isolated a Saccharomyces cerevisiae gene, termed NTA1, that encodes an amidase (Nt-amidase) specific for N-terminal asparagine and glutamine. Alterations at the putative active-site cysteine of the 52-kDa Nt-amidase inactivate the enzyme. Null nta1 mutants are viable but unable to degrade N-end rule substrates that bear N-terminal asparagine or glutamine. The effects of overexpressing Nt-amidase and other components of the N-end rule pathway suggest interactions between these components and the existence of a multienzyme targeting complex.
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PMID:Yeast N-terminal amidase. A new enzyme and component of the N-end rule pathway. 774 55


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