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)

Peptidoglycan (PG) turnover in exponentially growing Neisseria gonorrhoeae RD5 type 4 was accompanied by release of soluble PG fragments into the medium. Turnover of the D-[14C]glucosamine-labeled glycan moiety and of the meso-[3H]diaminopimelic acid (DAP)-labeled peptide region occurred at similar rates (ca. 35% per generation). Turnover of D-[14C]alanine-labeled sites within the peptide side chain of PG occurred at roughly twice this rate; no turnover of L-[3H]proline-labeled protein was detected. Gel filtration of supernatants of cultures grown in the presence of labeled DAP, glucosamine, and D-alanine as described above and paper chromatography of hydrolyzed peak fractions revealed four major types of soluble PG. Two of these contained both peptide and glycan moieties and appeared to represent forms of disaccharide peptide monomers and dimers. The other two were (i) a 3H-labeled product lacking 14C and (ii) a 14C-containing product lacking 3H, which were similar in size to that expected for free tetrapeptides and free disaccharides, respectively. Together the appearance of these PG fragments and the concurrent turnover of glycan and peptide regions indicate that both glycan splitting and amidase PG hydrolase activities are involved in the turnover of PG in growing gonococci. If released during gonococcal infections, similar soluble PG fragments might influence the consequences of host-gonococcus interactions.
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PMID:Release of soluble peptidoglycan from growing gonococci: hexaminidase and amidase activities. 11 60

Human skin fibroblast lines of the infantile form of neuronal ceroid lipofuscinosis and control lines were cultured in the presence of [3H]glucosamine plus [3H]mannose and [35S]methionine. The labeled glycoconjugates were compared by quantitative polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The infantile form of the disease showed a 75% decrease of four glycoprotein components of M(r) 120-140 kDa. These components appeared to be N-linked glycoproteins as peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase (PNGase F) released 86-96% of the labeled carbohydrate from the labeled protein. These results suggest that the infantile form of this disease may be characterized by abnormalities in glycoconjugate metabolism leading to reduction of specific glycoproteins.
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PMID:Glycoprotein metabolism in neuronal ceroid lipofuscinosis fibroblasts. 141 45

The proteolysis of native glucosamine-6-phosphate synthase (Mr 67,000) from Escherichia coli was investigated using two nonspecific and five specific endoproteinases, alpha-chymotrypsin generated two nonoverlapping polypeptides CT1 and CT2 of Mr 40,000 and 27,000 lacking glucosamine-6P synthesizing activity. Amino terminal and carboxy terminal sequence analysis showed that cleavage occurred between positions 240 and 241 of the primary sequence without further degradation. The glutamine amidohydrolase activity was located in the CT2 N-terminal polypeptide which was capable of incorporating 0.7 equivalent of the glutamine site-directed affinity label [2-3H]-N3-(4-methoxyfumaroyl)-diaminopropionic acid indicating that it bears the amidotransferase function. CT1 which displayed a higher reactivity than CT2 for fructose-6P binding contains the ketose/aldose isomerase activity. These data suggest the existence of a hinge structure essential for the catalytically efficient coupling between the ammonia generating domain and the sugar binding domain and support the model recently proposed by Mei and Zalkin in which purF-type amidotransferases contain a glutamine hydrolase domain of approximately 200 amino acids fused to an ammonia-transfer domain.
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PMID:Glucosamine-6-phosphate synthase from Escherichia coli yields two proteins upon limited proteolysis: identification of the glutamine amidohydrolase and 2R ketose/aldose isomerase-bearing domains based on their biochemical properties. 189 18

Pneumococcal peptidoglycan amidase (N-acetylmuramoyl-L-alanine amidase, EC 3.5.1.28) and phage CPL1 lysozyme degrade a common substrate (choline-containing pneumococcal cell walls); the former hydrolyzes the bond between muramic acid and alanine, whereas the latter breaks down the linkage between muramic acid and glucosamine. The amino acid sequences of their C-terminal domains are homologous. Chimeric genes were constructed by site-directed mutagenesis: a unique SnaBI restriction site in the cpl1 gene, coding for the phage lysozyme, was introduced at a location equivalent to the SnaBI site present in the lytA gene, which codes for the pneumococcal amidase. The resulting genes expressed lytic activities at levels similar to those of the parental genes. The gene products, which have been purified to electrophoretical homogeneity, exhibited unusual combined biochemical properties--e.g., by exchange of protein domains, we have switched the regulatory properties of these enzymes without altering their catalytic activities. Chimeric gene construction in Streptococcus pneumoniae and its bacteriophages is an excellent model to study the modular organization of genes and proteins and to help to establish evolutionary relationships between phage and bacteria. These constructions provide an experimental approach to the molecular processes involved in cassette recruitment during evolution and contribute support to the concept of bacteria as adaptable chimeras.
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PMID:Chimeric phage-bacterial enzymes: a clue to the modular evolution of genes. 197 20

The DNA sequence of a 3.6kb region downstream of the nagB gene (encoding glucosamine-6-PO4-deaminase) in Escherichia coli has been determined. Three open reading frames, which are subsequently referred to as nagA, nagC and nagD, were detected in this sequence. Genetic complementation and enzyme assays have shown that the first of these, nagA, encodes N-acetyl glucosamine-6-phosphate deacetylase. Growth on N-acetyl glucosamine induces the synthesis of a 1900 nucleotide long transcript which covers just nagE, encoding EIINag which is transcribed divergently from nagB, and of a 4200 nucleotide long transcript which covers all four ORFs of the nagB,A,C, D operon. More mRNA corresponding to nagB and nagA is detected than that corresponding to the distal genes, nagC and nagD. Considerable amounts of the induced mRNA are truncated molecules having their 3' ends after nagB and after nagA. Multiple 3' RNA ends have been mapped after nagD and seem to correspond to the ends of transcripts stabilized by mRNA secondary structure (REP sequences) rather than transcription termination sites. A second promoter producing nagD-specific transcripts has been mapped just in front of the nagD gene.
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PMID:Sequence of the nagBACD operon in Escherichia coli K12 and pattern of transcription within the nag regulon. 266 91

By inserting a lambda placMu bacteriophage into gene glmS encoding glucosamine 6-phosphate synthetase (GlmS), the key enzyme of amino sugar biosynthesis, a nonreverting mutant of Escherichia coli K-12 that was strictly dependent on exogenous N-acetyl-D-glucosamine or D-glucosamine was generated. Analysis of suppressor mutations rendering the mutant independent of amino sugar supply revealed that the catabolic enzyme D-glucosamine-6-phosphate isomerase (deaminase), encoded by gene nagB of the nag operon, was able to fulfill anabolic functions in amino sugar biosynthesis. The suppressor mutants invariably expressed the isomerase constitutively as a result of mutations in nagR, the locus for the repressor of the nag regulon. Suppression was also possible by transformation of glmS mutants with high-copy-number plasmids expressing the gene nagB. Efficient suppression of the glmS lesion, however, required mutations in a second locus, termed glmX, which has been localized to 26.8 min on the standard E. coli K-12 map. Its possible function in nitrogen or cell wall metabolism is discussed.
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PMID:Alternative route for biosynthesis of amino sugars in Escherichia coli K-12 mutants by means of a catabolic isomerase. 268 46

Four genes, nagR, A, B and E, clustered in the nag locus of Escherichia coli K12 and Klebsiella pneumoniae, were cloned and physically mapped, and the corresponding gene products involved in amino sugar metabolism identified. Expression of the nag genes was also analysed using a series of lacZ fusions. In both bacteria, the genes are arranged in two divergent operons and controlled by a common NagR repressor. The corresponding gene nagR was found to map in the first operon together with the promoter proximal gene nagB, encoding the enzyme D-glucosamine isomerase (deaminase) (NagB) and the middle gene nagA, coding for N-acetyl-glucosamine deacetylase (NagA). Polar mutations in nagB and nagA prevent the efficient expression of nagR and cause constitutive expression of all nag genes. This includes the gene nagE encoding Enzyme IINag of the phosphoenolpyruvate-dependent carbohydrate phosphotransferase system (PTS), encoded in the second divergently transcribed operon. No further gene is found in this operon which in both organisms is directly adjacent to the gene glnS. It is interesting that the NagR repressor also affects the mannose PTS (genes manX, Y, Z), the second transport system involved in amino sugar uptake and phosphorylation.
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PMID:Analysis of the nag regulon from Escherichia coli K12 and Klebsiella pneumoniae and of its regulation. 269 51

Enzymatic deacylation of the lipopolysaccharide isolated from a Salmonella Rd mutant by a cell-free preparation from Acanthamoeba castellanii has been studied. The degradation was found to be dependent on the presence of a surface-active component (Triton X-100) in the reaction mixture. The lipid A part of the lipopolysaccharide was the primary target of the enzymes, which cleaved with high efficiency the ester-bound long-chain nonhydroxylated and 3-hydroxylated acyl residues, i.e. lauric, myristic, palmitic and 3-hydroxymyristic acid. The cell-free preparation also exhibited amidase activity cleaving about 50% of the amide-bound 3-hydroxymyristic acid residues. In addition the extract proved to possess phosphatase activity liberating ester-bound and glycosidically bound phosphate groups of lipid A. On the other hand, the glucosaminyl-beta 1,6-glucosamine disaccharide was not degraded and remained bound to the oligosaccharide part (heptose/3-deoxyoctulosonic acid) of the lipopolysaccharide.
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PMID:In vitro deacylation of lipopolysaccharide of Salmonella minnesota by Acanthamoeba castellanii enzymes. 300 30

A perfused rat liver was used to study the effects of 5-diazo-4-oxo-L-norvaline on lysosomal glycoprotein catabolism. Addition of this compound (1.0 mM) to the perfusate reduced activity of beta-aspartyl-N-acetylglucosylamine amidohydrolase by 99% in 1 h. Treated livers were unable to completely degrade endocytosed N-acetyl[14C]glucosamine-labeled asialo-alpha 1-acid glycoprotein as evidenced by a 50% reduction in radiolabeled serum glycoprotein secretion compared to controls. This decreased degradation was matched by a lysosomal accumulation of glycopeptides with the structure: GlcNAc beta(1-4)GlcNAc-Asn. The result suggested the presence of an unrecognized glycosidase in rat liver lysosomes, since this remnant was extended by one more GlcNAc residue than would have been expected after specific inactivation of the amidohydrolase. Such a novel enzyme would therefore catalyze cleavage of the N-acetylglucosamine residue at the reducing end of alpha 1-acid glycoprotein oligosaccharides only following removal of the linking Asn. The activity was then detected in lysosomal extracts by using intact asialo-biantennary oligosaccharides labeled with [3H] galactose or N-acetyl[14C]glucosamine residues as a substrate. To prevent simultaneous digestion of the material from its nonreducing end, beta-D-galactosidase in the enzyme extract was first inactivated with the irreversible active site-directed inhibitor, beta-D-galactopyranosylmethyl-p-nitrophenyltriazene. The observed di-N-acetylchitobiose cleaving activity worked optimally at pH 3.4 and was uniquely associated with the lysosomal fraction of the liver homogenate. The enzyme also cleaved triantennary chains and di-N-acetylchitobiose, but failed to hydrolyze substrates that had been reduced with NaBH4. The new glycosidase was well separated from N-acetyl-beta-D-glucosaminidase (assayed with p-nitrophenyl-beta-D-glucosaminide) by gel filtration chromatography and had an apparent molecular weight of 37,000. A similar enzyme that hydrolyzes di-N-acetylchitobiose had previously been found in extracts of human liver (Stirling, J. L. (1974) FEBS Lett. 39, 171-175).
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PMID:A di-N-acetylchitobiase activity is involved in the lysosomal catabolism of asparagine-linked glycoproteins in rat liver. 308 72

In the reverse direction, the reaction catalyzed by glucosamine 6-phosphate isomerase deaminase consumes ammonia and forms GlcN6P. As a consequence of the formation of a product with a lower pK than the substrates, a measurable pH drop in the reaction medium is produced. This property can be used to follow potentiometrically the course of the reaction. This property can be used to follow potentiometrically the course of the reaction. The usefulness of the method is demonstrated obtaining the inhibition pattern by GlcN6P when Fru6P is the varied substrate.
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PMID:pHmetrical determination of the glucosamine-6-phosphate isomerase deaminase reverse reaction. 329 61


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