Enzymes, extracellular

An extracellular enzyme [levan fructotransferase, (EC 2.4.1.10)] that carries out an intramolecular transfructosylation upon levan to produce (3-D-Fru/-2,6 6,2 -f)-D-Fru/ [difructose anhydride IV (7)] has been identified in A. ure-afaciens.54,55... 

Barras, F., van Gijsegem, F. and Chatterjee, A. K. (1994). Extracellular enzymes and pathogenesis of soft-rot Erwinia. Annu Rev Phytopathol 32, 201-234. 

Digestion of PGA by the PelL enzyme yielded a mixture of unsaturated ohgogalacturonides, giving evidence that PelL is an endo-deaving lyase (17). An exo-enz3mie, such as the EC 16 PelX, would generate a single product (15). The PelL protein differs from the major E. chrysanthemi pectate lyases in its ability to cleave both PGA and methylated pectin (17). The PelL activity has a basic optimum pH and an absolute requirement for Ca + ions. Analysis of culture supernatants demonstrated that PelL is an extracellular enzyme, such as the other secondary pectate lyases (17). 

Culture m ium supernatant was used as a source of extracellular enzymes. PG activity Two methods were used to measure PG activity (versus polygalacturonic acid Na-... 

Extracellular Enzyme Activities. The protein, carrier of the polygalacturonase and pectinmethylesterase activities, was salted out from the H.annuus 1805 culture medium by adding ammonium sulphate to 70 % saturation. The precipitate was separated by centrifugation (30 min, 4500 xg), diluted with 0.1 M phosphate buffer (pH 7.0) and dialyzed for 12 hours against distilled water. After dilution to the required volume with the same buffer, both enzyme activities under study were determined in the solution. 

They may produce extracellular enzymes, which attack the substrate without the need for transport into the cell, for example, cellulase, DNAse, or gelatinase. 

An extracellular enzyme from Xanthomonas sp. is able to degrade poly(c -l,4-isoprene) with the production of 12-keto-4,8-dimethyltrideca-4,8-diene-l-al (Braaz et al. 2004), and functions as a heme-dependent oxygenase (Braaz et al. 2005). 

Although a few mechanisms have so far been proposed to explain the antimicrobial properties exhibited by proanthocyanidins (e.g., inhibition of extracellular enzymes) [86], Jones et al. [83] postulated that their ability to bind bacterial cell coat polymers and their abihty to inhibit cell-associated proteolysis might be considered responsible for the observed activity (Table 1). Accordingly, despite the formation of complexes with cell coat polymers, proanthocyanidins penetrated to the cell wall in sufficient concentration to react with one or more ultra-structural components and to selectively inhibit cell wall synthesis. Decreased proteolysis in these strains may also reflect a reduction of the export of proteases from the cell in the presence of proanthocyanidins [83]. 

All soil metabolic proce.sses are driven by enzymes. The main sources of enzymes in soil are roots, animals, and microorganisms the last are considered to be the most important (49). Once enzymes are produced and excreted from microbial cells or from root cells, they face harsh conditions most may be rapidly decomposed by organisms (50), part may be adsorbed onto soil organomineral colloids and possibly protected against microbial degradation (51), and a minor portion may stand active in soil solution (52). The fraction of extracellular enzyme activity of soil, which is not denaturated and/or inactivated through interactions with soil fabric (51), is called naturally stabilized or immobilized. Moreover, it has been hypothesized that immobilized enzymes have a peculiar behavior, for they might not require cofactors for their catalysis. 

F. Asmar and G. Gisselnielsen, Extracellular phosphomono- and phosphodiestera.se as.sociated with and relea.sed by the roots of barley genotypes a nondestructive method for the measurement of the extracellular enzymes of roots. Biol. Fertil. Soils 25 117 (1997). 

Produce extracellular enzymes that promote tissue invasion... 

It is a well-known fact that specific plastic materials like flexible PVC, Polyurethane or Silicone may be easily attacked by microorganisms leading to discoloration or mechanical failures.14 This susceptibility to microbial attack is mainly attributed to the plasticiser content of the material as well as other ingredients such as stabiliser or antioxidants.5,6 The predominant organisms on the surface of those plastics are fungi and actinomycetes and it is said that by the action of their extracellular enzymes other organisms such as bacteria may be able to grow on the material.7... 

A 25 - 38 amino acid long signal peptide, which is characteristic for extracellular enzymes and is cleaved off during the passage across the cytoplasma membrane. 

The role of extracellular enzymatic systems in the degradation of triiodinated aromatics compounds was demonstrated by the same authors. Degradation yields between 87% and 93% for diatrizoate, iodipamide, and acetrizoate, and between 68% and 73% for aminotrizoate and aminotriiodoisophthalate were observed in in vitro experiments with extracellular enzyme concentrate of T. versicolor in the... 

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