Effectors differently modulating the dextransucrase activity of Leuconostoc mesenteroides.

Kobayashi, Mikihiko; Yokoyama, Ikuko; Matsuda, Kazuo

doi:10.1271/bbb1961.49.3189

Cited by 12 publications

(7 citation statements)

References 3 publications

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“…It has been proposed that glucan is bound to the enzyme through non‐covalent links [38]. More recently, results coming from inhibition kinetic studies using various agents suggested that the glucan binding site was separated from the sucrose binding site [47–51]. This hypothesis has also been confirmed by the identification of glucansucrase sequences and by structure–function relationship studies (see ).…”

Section: Mechanism Of Glucansucrase Actionmentioning

confidence: 89%

Glucansucrases: mechanism of action and structure–function relationships

1999

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Glucansucrases are produced principally by Leuconostoc mesenteroides and oral Streptococcus species, but also by the lactic acid bacteria (Lactococci, Lactobacilli). They catalyse the synthesis of high molecular weight D-glucose polymers, named glucans, from sucrose. In the presence of efficient acceptors, they catalyse the synthesis of low molecular weight oligosaccharides. Glucosidic bond synthesis occurs without the mediation of nucleotide activated sugars and cofactors are not necessary. Glucansucrases have an industrial value because of the production of dextrans and oligosaccharides and a biological importance by their key role in the cariogenic process. They were identified more than 50 years ago. The first glucansucrase encoding gene was cloned more than 10 years ago. But the mechanism of their action remains incompletely understood. However, in order to synthesise oligosaccharides of biological interest or to develop vaccines against dental caries, elucidation of the factors determining the regiospecificity and the regioselectivity of glucansucrases is necessary. The cloning of glucansucrase encoding genes in addition to structure-function relationship studies have allowed the identification of important amino acid residues and have shown that glucansucrases are composed of two functional domains: a core region (ca. 1000 amino acids) involved in sucrose binding and splitting and a C-terminal domain (ca. 500 amino acids) composed of a series of tandem repeats involved in glucan binding. Enzymology studies have enabled different models for their action mechanism to be proposed. The use of secondary structure prediction has led to a clearer knowledge of structure-function relationships of glucansucrases. However, mainly due to the large size of these enzymes, data on the three-dimensional structure of glucansucrases (given by crystallography and modelling) remain necessary to clearly identify those features which determine function.

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Section: Mechanism Of Glucansucrase Actionmentioning

confidence: 89%

Glucansucrases: mechanism of action and structure–function relationships

1999

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“…Another substance that can inhibit the growth of L. mesenteroides, sodium dodecylsulfate (SDS), also known as lau- ryl sulfate, was added to solutions containing 15 g/L sucrose. SDS was chosen as a growth inhibitor because of its documented success in reducing the effectiveness of sucrose cleavage by dextransucrase (Kobayashi et al, 1985). For the conditions used in the growth experiments, the SDS critical micelle concentration (CMC), was approximately 0.8 mM (Hiemenz and Rajagopalan, 1997).…”

Section: Sodium Dodecylsulfate Inhibitionmentioning

confidence: 99%

Alteration of the growth rate and lag time of Leuconostoc mesenteroides NRRL‐B523

Wolf¹,

Fogler²

2001

Biotechnol. Bioeng.

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Bacterial profile modification is an important enhanced oil recovery technique used to direct injected water into a reservoir's low permeability zone containing trapped crude oil. During water flooding, the use of bacteria to plug the high permeability water zone and divert flow into the oil-bearing low-permeability zone will have a significant economic impact. However, during the field implementation of bacterial profile modification, the rapid growth of bacteria near the injection well bore may hinder the subsequent injection of growth media so that profile modification of the reservoir occurs only in the immediate vicinity of the well bore. By slowing the growth rate and prolonging the lag phase, the onset of pore-space plugging may be delayed and the biologically active zone extended deep into the reservoir. High substrate loading, high pH values, and the addition of the growth inhibitors sodium dodecylsulfate and sodium benzoate have been used in combination to alter the growth characteristics of Leuconostoc mesenteroides NRRL-B523 grown in batch conditions. The highest sucrose concentration used in these studies, 500 g/L, produced lag times 12-fold greater than the slowest lag times achieved at low sucrose concentrations. When L. mesenteroides was grown in media containing 500 g/L sucrose, an alkaline pH value threshold was found above which bacteria did not grow. At this threshold pH value of 8.1, an average lag time of 200 h was observed. Increasing the concentration of sodium benzoate had no effect on lag time, but reduced the growth rate until the threshold concentration of 0.6%, above which bacteria did not grow. Last, it was found that a solution of 0.075 mM sodium dodecylsulfate in media containing 15 g/L sucrose completely inhibited bacterial growth.

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“…Some are mentioned briefly in the following. Kobayashi et al suggested that the dextransucrase reaction should be separated into sucrase and transferase steps with respect to the action of effectors [31]. We follow the theory of the insertion mechanism assumed by Ebert and Schenk as well as Kindler and Ludwig and later on extended by Robyt et al: The glucosyl moiety of the substrate sucrose is linked covalently to dextransucrase and simultaneously fructose is released.…”

Section: Insertion Mechanism and Acceptor Reactionmentioning

confidence: 96%