Glucanase

Endo-β-1,4-glucanase là một trong ba dạng của cellulase. Chúng thuộc nhóm enzyme thủy phân, có khả năng phân cắt liên kết β-1,4-glucosidie một cách ngẫu nhiên bên trong phân tử cellulose, oligosaccharide, disaccharide và một số chất tƣơng tự khác có cầu nối β-glucan. Endo-β-1,4-glucanase phân giải mạnh mẽ cellulose vô định hình

90p tangtocmuathi 23-05-2013 148 30   Download

Cellulose là một thành phần quan trọng cấu tạo nên lớp thành tế bào thực vật. Đó là một loại polysaccharide có cấu trúc phức tạp. Việc phân hủy cellulose bằng các tác nhân lý hóa gặp nhiều khó khăn, làm ảnh hƣởng đến tốc độ của nhiều quá trình sản xuất công nghiệp.

97p tangtocmuathi 22-05-2013 95 13   Download

Chuyển gen là phương pháp gây biến dị di truyền có định hướng ở cây trồng (Rosen và cs., 2003; Veluthambi và cs., 2003; Sung Hun Park và cs., 2003) đã và đang được áp dụng rộng rãi trong những năm gần đây. Trong nghiên cứu tạo ra cây chuyển gen kháng bệnh, các nhà khoa học đã phát hiện được gen Chitinase trong cây trồng có khả năng hạn chế sự phát triển các loại nấm gây bệnh cây như Fusarium, Botrytis cinerea, Rhizoctonia, hạn...

6p shop_123 09-05-2013 109 14   Download

An exo-1,3-b-glucanase has been isolated from cultural filtrate of Trichoderma viride AZ36. The N-terminal sequence of the purified enzyme (m ¼ 61 ^ 1 kDa) showed no significant homology to other known glucanases. The 1,3-b-glucanase displayed high activity against laminarins, curdlan, and 1,3-b-oligoglucosides, but acted slowly on 1,3-1,4-b-oligoglucosides. No significant activity was detected against high molecular mass 1,3-1,4-bglucans. The enzyme carried out hydrolysis with inversion of the anomeric configuration.

9p system191 01-06-2013 46 6   Download

A cellulase (endo-b-1,4-glucanase, EC 3.2.1.4) was purified from the gut of larvae of the yellow-spotted longicorn beetle Psacothea hilarisby acetone precipitation and elution from gels after native PAGE and SDS/PAGE with activity staining. The purified protein formed a single band, and the molecular mass was estimated to be 47 kDa. The purified cellulasedegradedcarboxymethylcellulose (CMC), insoluble cello-oligosaccharide (average degree of polymerization 34) and soluble cello-oligosaccharides longer than cellotriose, but not crystalline cellulose or cellobiose. ...

6p tumor12 20-04-2013 40 5   Download

A cellulase [endo-b-1,4-D-glucanase (EC 3.2.1.4)] was iso-lated from the hepatopancreas of abalone Haliotis discus hannaiby successive chromatographies on TOYOPEARL CM-650M, hydroxyapatite and Sephacryl S-200 HR. The molecular mass of the cellulase was estimated to be 66 000 Da by SDS/PAGE, thus the enzyme was named HdEG66. The hydrolytic activity of HdEG66 toward carb-oxymethylcellulose showed optimal temperature and pH at 38
Cand 6.3, respectively.

8p tumor12 20-04-2013 46 4   Download

The structural features of the hyperthermophilic endo-b-1,3-glucanase from Pyrococcus furiosuswere studied using circular dichroism, steady-state and time-resolved fluorescence spectroscopy and anisotropy. Upon heat and chemical treatment the folded and denatured states of the protein were characterized by distinguishable spectral profiles that identified a number of conformational states.

13p fptmusic 12-04-2013 39 2   Download

A new component of theb-1,6-glucanase (EC 3.2.1.75) multienzymatic complex secreted by Trichoderma harzianumhas been identified and fully characterized. The protein, namely BGN16.3, is the third isozyme display-ing endo-b-1,6-glucanase activity described up to now in T. harzianum CECT 2413. BGN16.3 is an acidicb-1,6-glucanase that is specifically induced by the presence of fungal cell walls in T. harzianumgrowth media.

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Trichodermaspecies have been investigated as biological control agents for over 70 years owing to their ability to antagonize plant pathogenic fungi. Mycoparasitism, one of the main mechanisms involved in the antagonistic activity ofTrichodermastrains, depends on the secretion of complex mix-tures of hydrolytic enzymes able to degrade the host cell wall. The antifun-gal activity of an a-1,3-glucanase (EC 3.2.1.59, enzymes able to degrade a-1,3-glucans and also named mutanases) has been described in T. harzia-num and its role in mycoparasitic processes has been suggested....

0p awards 05-04-2013 44 4   Download

The thermodynamic stability of family 16 endo-b-1,3-glucanase (EC 3.2.1.39) from the hyperthermophilic archaeon Pyrococcus furiosusis decreased upon single (D287A, E53A) and double (E53A⁄D287A) muta-tion of Asp287 and Glu53. In accordance with the homology model predic-tion, both carboxylic acids are involved in the composition of a calcium binding site, as shown by titration of the wild-type and the variant proteins with a chromophoric chelator.

13p media19 05-03-2013 38 4   Download

The thermal denaturation of endo-b-1,3-glucanase from the hyperthermo-philic microorganismPyrococcus furiosuswas studied by calorimetry. The calorimetric profile revealed two transitions at 109 and 144C, correspond-ing to protein denaturation and complete unfolding, respectively, as shown by circular dichroism and fluorescence spectroscopy data.

9p media19 05-03-2013 29 3   Download

Bacterial and archaeal endo-b-1,3-glucanases that belong to glycoside hydrolase family 16 share a b-jelly-roll fold, but differ significantly in sequence and in substrate specificity. The crystal structure of the laminarin-ase (EC 3.2.1.39) from the hyperthermophilic archaeonPyrococcus furiosus (pfLamA) has been determined at 2.1 A˚ resolution by molecular replace-ment. ThepfLamA structure reveals a kink of six residues (72–77) at the entrance of the catalytic cleft.

11p vinaphone15 27-02-2013 35 4   Download

Geotrichumsp. M128 possesses two xyloglucan-specific glycoside hydrolases belonging to family 74, xyloglucan-specific endo-b-1,4-glucanase (XEG) and oligoxyloglucan reducing-end-specific cellobiohydrolase (OXG-RCBH). Despite their similar amino acid sequences (48% identity), their modes of action and substrate specificities are distinct.

7p vinaphone15 25-02-2013 36 3   Download

The 1,3(4)-b-d-glucanases of glycoside hydrolase family 16 provide useful examples of versatile yet specific protein–carbohydrate interactions. In the present study, we report the X-ray structures of the 1,3(4)-b-d-glucanase Phanerochaete chrysosporiumLaminarinase 16A in complex withb-glucan products from laminarin (1.6 A˚ ) and lichenin (1.1 A ˚ ) hydrolysis. The G6G3G3G glucan, in complex with the enzyme, showed ab-1,6 branch in the acceptor site.

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Candida albicansexo-b-1,3-glucanase (Exg; EC 3.2.1.58) is implicated in cell wall b-d-glucan remodelling through its glucosyl hydrolase and⁄or transglucosylase activities. A pair of antiparallel phenylalanyl residues (F144 and F258) flank the entrance to the active site pocket. Various Exg mutants were studied using steady-state kinetics and crystallography aiming to understand the roles played by these residues in positioning the b-1,3-d-glucan substrate.

13p viettel02 19-02-2013 53 8   Download

b-Linked glucans such as cellulose and xyloglucan are important compo-nents of the cell walls of most dicotyledonous plants. Theseb-linked glu-cans are constantly exposed to degradation by various endo-b-glucanases from pathogenic bacteria and fungi.

11p cosis54 05-01-2013 50 6   Download

Cellulose là một thành phần quan trọng cấu tạo nên lớp thành tế bào thực vật. Đó là một loại polysaccharide có cấu trúc phức tạp. Việc phân hủy cellulose bằng các tác nhân lý hóa gặp nhiều khó khăn, làm ảnh hƣởng đến tốc độ của nhiều quá trình sản xuất công nghiệp. Endo-β-1,4-glucanase (3.2.1.4) là một trong ba loại enzyme thuộc hệ enzyme thủy phân cellulose (cellulase). Enzyme này tham gia phân cắt ngẫu nhiên các liên kết β-1,4 glucoside từ bên trong các phân tử cellulose và một số loại polysaccharide tƣơng tự khác tạo thành các oligosaccharide....

97p carol123 19-07-2012 120 31   Download