Dataset Information

The action on cellulose and its derivatives of a purified 1,4-beta-glucanase from Trichoderma koningii.

ABSTRACT: The specific properties have been examined of the 1,4-beta-glucanase component of Trichoderma koningii that participates in an early and effective stage of random breakdown of native cellulose to short fibres. The enzyme was purified and freed from associated components of the cellulase complex (particularly beta-glucosidase) that interfere with, and complicate interpretation of, the action of such enzymes. Purification increased the specific activity 25-fold over culture filtrates; the enzyme hydrolysed CM-cellulose faster than the purified beta-glucosidase from the same organism hydrolysed any of its substrates (cellobiose or cellodextrins). The specificity of the glucanase was directed towards soluble derivatives of cellulose, CM-cellulose and cellodextrins, and not to insoluble cellulose or alpha-linked polymers. The approximate Km was 2.5 mg of CM-cellulose . ml-1 at 37 degrees C at the optimum pH, 5.5, where enzymic activity was maximal with 6--7 mg of CM-cellulose . ml-1 and inhibited by higher concentrations. The temperature optimum was 60 degrees C. The glucanase attacked larger cellodextrins (cellohexaose to cellotetraose, in that order) much more readily than smaller dextrins (cellobiose and cellotriose) and released a mixture of products, glucose up to cellopentaose, which was quantitatively determined after chromatography on charcoal. Similar examination of hydrolysates of the reduced cellodextrins showed clearly the high specificity of the enzyme for the central bond of its natural substrates (the cellodextrins), whatever their chain length, and indicated the nature of the enzyme as an endoglucanase. Outer bonds shared a weaker, but similar, susceptibility to enzymic cleavage. Transferase activity was absent and no larger dextrins than the initial substrate were formed.

SUBMITTER: Halliwell G

PROVIDER: S-EPMC1163384 | biostudies-other | 1981 Nov

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:The food enzyme containing cellulase (EC 3.2.1.4), endo-1,3(4)-β-glucanase (EC 3.2.1.6) and endo-1,4-β-xylanase (EC 3.2.1.8) is produced with the non-genetically modified Trichoderma reesei strain AR-256 by AB-Enzymes GmbH. The food enzyme is considered free from viable cells of the production organism. It is intended to be used in seven food manufacturing processes: baking processes, cereal-based processes, brewing processes, fruit and vegetable processing for juice production, wine and wine vinegar production, distilled alcohol production and grain treatment for production of starch and gluten fractions. Since the residual amounts of total organic solids (TOS) are removed during grain treatment and distilled alcohol production, dietary exposure was estimated for the remaining five processes and amounted up to 3.92 mg TOS/kg body weight (bw) per day. The toxicity studies were carried out with an endo-1,4-β-xylanase from T. reesei ■■■■■, considered by the Panel as a suitable substitute, because the genetic differences between the strains are well characterised and of no concern. Additionally, several strains derived from the production strain are considered safe by EFSA and the manufacturing of both food enzymes is similar. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by a repeated dose 90-day oral toxicity rat study. The no observed adverse effect level of 939 mg TOS/kg bw per day, the highest dose tested, compared with the estimated dietary exposure, resulted in a margin of exposure above 239. In the search for the similarity of the amino acid sequences to known allergens, one match (salmon) was found. The Panel considered that, under the intended conditions of use (except distilled alcohol production), the risk of allergic reactions by dietary exposure cannot be excluded, in particular for individuals sensitised to salmon. The Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Dataset Information

The action on cellulose and its derivatives of a purified 1,4-beta-glucanase from Trichoderma koningii.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets