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

---

Query: EC:4.1.2.13 (aldolase)
3,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The production of neuraminidase by a classical strain of Clostridium welchii (C. perfringens) type A was studied. Good yields were produced in 5% Proteose Peptone-water medium (PPW5); the enzyme was essentially extracellular but some further neuraminidase could be released by ultrasonic disintegration of the cells. This also released N-acyl neuraminic acid-aldolase (NAN-aldolase) and the degree to which this interferes with the assay for neuraminidase was evaluated. Forty-one British reference food-poisoning strains of C. welchii type A were examined for extracellular neuraminidase production in PPW5. Twelve of 17 strains that produce so-called heat-sensitive spores were neuraminidase positive whereas 20 of 24 strains that are non-haemolytic and produce very heat-resistant sporeswere neuraminidase negative. Variation was found in the ability to produce neuraminidase among strains of a single Hobbs' serotype; four Hobbs' type-13 strains produced neuraminidase but a fifth did not. Disruption of the cells of a Hobbs' type-2 strain that did not produce any extracellular neuraminidase released NAN-aldolase but there was no evidence of cell-associated neuraminidase. British food-poisoning strains of C. welchii type A thus include some that are clearly neuraminidase positive and some that still cannot be shown to produce neuraminidase. There is no correlation between lack of neuraminidase production and the ability to cause food poisoning, although the majority of non-haemolytic heat-resistant strains do not produce neuraminidase. It remains possible that neuraminidase may play a part in C. welchii gas gangrene; it is suggested that the ability to define neuraminidase-negative strains may now be of value in investigating this possibility.
...
PMID:The production of neuraminidase by food poisoning strains of Clostridium welchii (C. perfringens). 16 69

The production of neuraminidase (EC 3.2.1.18) by a range of clostridial species was investigated with techniques previously developed to distinguish neuraminidase-negative and neuraminidase-positive strains of Clostridium perfringens (welchii). Large amounts of extracellular neuraminidase were produced by representative strains of C. perfringens and C. septicum in the test media. Under similar conditions, two strains each of C. chauvoei and C. tertium were found to produce small amounts of the enzyme. All of 12 strains of C. sordellii were clearly shown to produce neuraminidase, often in large amounts, but none of five strains of the closely related but non-pathogenic C. bifermentans had demonstrable neuraminidase activity. No neuraminidase was produced by C. novyi (oedematiens) types A-D (10 strains), C. tetani (6), C. botulinum types A, B, C or E (4), C. sporogenes (4), C. histolyticum (4) or by single strains of five other clostridial species. Clostridial neuraminidase was predominantly extracellular and was not calcium-dependent. The investigation took account of variations in growth and enzyme production in different media. It was necessary to prolong the neuraminidase-assay reaction time to 24 h and to monitor for the presence of NAN-aldolase (EC 4.1.3.3) to define true negatives. It is suggested that neuraminidase production may be of value in taxonomic studies and that its production by several pathogenic species of clostridia may be of interest in studies of pathogenicity and virulence.
...
PMID:Neuraminidase production by clostridia. 21 Feb 77

1H-NMR spectroscopy was used to study cleavage and synthesis of N-acetyl- and N-glycoloyl-D-neuraminic acid by Clostridium perfringens aldolase. Whereas the alpha-anomers of Neu5Ac and Neu5Gc serve as substrate in the cleavage reaction, alpha-ManNAc and alpha-ManNGc are its primary products. The same alpha-anomers are needed by the aldolase for the synthesis of Neu5Ac and Neu5Gc. During the enzyme reaction in D2O both H-atoms at C-3 of Neu5Ac are exchanged by deuterium, H-3e reacting faster than H-3a. Rate constants and concentrations at equilibrium of reactants are temperature- and pH-dependent: The amount of Neu5Ac in equilibrium increases with decreasing temperature and increasing pH-value. Based on these results a mechanism of aldolase action is discussed.
...
PMID:[Cleavage and synthesis of sialic acids with aldolase. NMR studies of stereochemistry, kinetics, and mechanisms]. 253 41

Sialic acid has been assayed enzymatically by an immobilized two-enzyme system. The method includes cleavage of sialic acid to pyruvic acid by N-acetylneuraminic acid (NANA) aldolase and reduction of pyruvic acid by lactate dehydrogenase in the presence of NADH, which is followed photometrically at 349 nm. For the membrane preparation 5 units of lactate dehydrogenase and 1 unit of NANA-aldolase were used. The pH optimum of the reaction using potassium phosphate buffer was 7.0. This two-enzyme membrane remains 100% active for several weeks at 4 degrees C in the assay buffer and remains stable after performing experiments at 45 degrees C.
...
PMID:An immobilized bienzyme system for assay of sialic acid. 287 18

We show that the 4-oxo analogue of N-acetyl-D-neuraminic acid strongly inhibits N-acetylneuraminate lyase (NeuAc aldolase, EC 4.1.3.3) from Clostridum perfringens (Ki = 0.025 mM) and Escherichia coli (Ki = 0.15 mM). In each case the inhibition was competitive. N-Acetyl-D-neuraminic acid; N-Acetylneuraminate lyase; N-Acetyl-D-neuraminic acid analog; 5-Acetamido-3,5-dideoxy-beta-D-manno-non-2,4-diulosonic acid; 2-Deoxy-2,3-didehydro-N-acetyl-4-oxo-neuraminic acid; Competitive inhibitor.
...
PMID:Inhibition of N-acetylneuraminate lyase by N-acetyl-4-oxo-D-neuraminic acid. 289 4

N-Acetylneuraminic acid aldolase from Clostridium perfringens was irreversibly inactivated by 1mm-bromopyruvate with a half-life of 4.2min at pH7.2 and 37 degrees C. The rate of inactivation was diminished in the presence of pyruvate but not with N-acetyl-d-mannosamine, indicating that the inhibitor acted at, or close to, the pyruvate-binding site. The apparent K(i) for bromopyruvate, calculated from the variation of half-life with inhibitor concentration, was 0.46mm, compared with a competitive K(i) 3.0mm for pyruvate. Incubation of the enzyme with radioactive bromopyruvate gave a radioactive, enzymically inactive, protein in which the bromopyruvate had alkylated cysteine residues. Incubation of the enzyme with radioactive pyruvate, followed by reduction with sodium borohydride, led to inactivation of the enzyme and binding of the pyruvate to the protein by reduction of a Schiff's base initially formed with the in-amino group of a lysine residue; only one-twentieth as many pyruvyl residues were bound by this method, showing that bromopyruvate is not specific for the active site. After protection of the enzyme active site with pyruvate, treatment with unlabelled bromopyruvate and dialysis, the enzyme retained 72% activity. When this treated enzyme was separately incubated with radioactive bromopyruvate, or radioactive pyruvate followed by sodium borohydride, the ratio of radioactive pyruvyl residues bound by the two methods was 2.3:1. After reduction and hydrolysis of the bromopyruvate-treated enzyme, the only detectable radioactive amino acid derivative was chromatographically and electrophoretically identical with S-(3-lactic acid)-cysteine. The enzyme was fully active in the presence of EDTA and was not stimulated by bivalent metal ions. It was strongly inhibited by silver and mercuric ions. The apparent molecular weight, determined by Sephadex chromatography, was 250000. A mechanism of action is proposed for the enzyme. Bromopyruvate reacts rapidly at pH6.0 with thiol-containing amino acids. Cysteine appears to react anomalously.
...
PMID:Studies on N-acetylneuraminic acid aldolase. 433 37

To characterize the true substrate for aldolase from Clostridium perfringens (optimum pH = 7.2) several experiments were carried out wherein the substrate Neu5Ac was generated in situ at pH 5.4 by the action of sialidase on its substrate Neu5Ac(alpha, 2 leads to 3) lactose. The alpha-anomer formed in this reaction was found to be split by aldolase at this pH into ManNAc and pyruvate. beta-Neu5Ac as such was not converted at pH 5.4. However, when it was first mutarotated until the equilibrium mixture alpha:beta = 7.2:92.8 was obtained, it could be split. Inhibition experiments suggested that Neu5Ac was bound to the enzyme in a conformation that strongly resembled that of its alpha-anomer. The open chain form of ManNAc which arose after the action of aldolase preferentially formed the alpha-anomer followed by a fast mutarotation.
...
PMID:Configuration of substrate and products of N-acetylneuraminate pyruvate-lyase from Clostridium perfringens. 630 75

The 9-amino or 9-N-acyl-5-trifluoroacetyl methyl alpha-ketosides (1a-c) and their 2,3-didehydro analogs (2a-c) have been synthesized through Neu5Ac aldolase-catalyzed aldol reaction of 6-azido-2-benzyloxycarbonylamino-2-deoxy-D-mannose with sodium pyruvate. The six compounds were investigated as inhibitors of sialidase from influenza virus. Compound 2b, a 2,3-didehydro type, showed the most potent inhibitory activity (IC50 > 7.8 microM) against the enzyme, whereas, compounds 1a-c as the methyl alpha-glycosides were found to be practically inactive (IC50 > 100 microM).
...
PMID:Chemoenzymatic synthesis of neuraminic acid analogs structurally varied at C-5 and C-9 as potential inhibitors of the sialidase from influenza virus. 858 91

N-acetyl-D-neuraminic acid (Neu5Ac) aldolase (EC 4.1.3.3) has bee reported for synthesis of Neu5Ac,1-5 but there are no reports of processes which do not have significant drawbacks for large-scale operation. Here, Neu5Ac aldolase from an overexpressing recombinant strain of Escherichia coli has been used to develop an immobilized enzyme process for production of Neu5Ac. The enzyme was immobilized onto Eupergit-C and could be reused many times in the reaction. Base-catalyzed epimerization of N-acetyl-D-glucosamine (GlcNAc) yielded GlcNAc/N-acetyl-D-mannosamine (ManNAc) mixtures (c 4:1) which could be used directly in the aldolase reaction; however, inhibition of the enzyme by GlcNAc limited the concentration of ManNAc which could be used in the reaction by this approach. This necessitated the addition of a large molar excess of pyruvate (five- to seven-fold) to drive the equilibrium over to Neu5Ac; nevertheless, a method has been developed to remove the excess pyruvate effectively by complexation with bisulfite, thus allowing Neu5Ac to be recovered by absorption onto an anion-exchange resin. In a second approach, a method has been developed to enrich GlcNAc/ManNAc mixtures for ManNAc. ManNAc can be used at high concentrations in the reaction, thus obviating the need to use a large molar excess of pyruvate. Neu5Ac can be isolated from such reaction mixtures by a simple crystallization. This work shows the importance of integrated process solutions for the effective scale-up of biotransformation reactions.
...
PMID:An efficient process for production of N-acetylneuraminic acid using N-acetylneuraminic acid aldolase. 908 8

The enzymatic synthesis of 2-keto-3-deoxy-D-glycero-D-galacto-nonopyranulosonic acid (KDN) starting from D-mannose and pyruvic acid using Neu5Ac-aldolase has been scaled up. A repetitive batch ultrafiltration bioreactor was used for the KDN synthesis on 100 g scale with a conversion of up to 85%. Furthermore, a 440 mL pilot-scale enzyme membrane reactor (EMR) was performed for the continuous production of KDN. Conversion of mannose was 75% at a space--time yield of 375 g/(L d). KDN was advanteageously isolated by crystallization with an overall yield of 75%.
...
PMID:Enzymatic large-scale production of 2-keto-3-deoxy-D-glycero-D-galacto-nonopyranulosonic acid in enzyme membrane reactors. 941 39


1 2 3 4 Next >>

---