Bacillus thuringiensis is a Gram-positive soil bacterium known as biopesticide bacteria that produce insecticidal proteins called protein crystals (Cry). In the process of insecticides, chitinase advisable to perforate the membrane barrier peritrophic to facilitate the invasion of Cry proteins to the membrane epithelium.
A chitinase gene from B. thuringiensis successfully expressed in soluble form in Escherichia coli and purified and characterized the gene product. Purified recombinant enzyme, BthChi74, hydrolyzed artificial substrates, 4-nitrophenyl N, N'-diacetyl-β-D-chitobioside [4NP- (GlcNAc) 2], and the natural substrate, colloidal chitin and crystal α-chitin, but it does not hydrolyze cellulose. BthChi74 shows the catalytic activity under weakly acidic to neutral pH Yeast Recombinant Proteins range at 50 ° C, and it was stable at broad pH range for 24 hours. Differential scanning Uranium (DSF) shows the protein melting temperature (T m) of 63.6 ° C.
The kinetic analysis revealed k cat and KM values of 1.5 s-1 and 159 pM, respectively, with 4NP- (GlcNAc ) 2 as a substrate. BthChi74 produced (GlcNAc) 2 and GlcNAc of colloidal chitin and α-chitin as substrate, but activity toward both lower than that toward the former. BthChi74 can bind similar to chitin beads, crystal α-chitin and cellulose through a unique family of two carbohydrate binding module (CBM2). BthChi74 structure-function relationship is discussed in relation to other chitinase, such as Listeria chitinase, who has a family of 5 carbohydrate binding module (CBM5).
Bifunctional recombinant cellulase-xylanase (rBhcell-xyl) from the bacterium Bacillus halodurans polyextremophilic TSLV1 and utility in raising the renewable agro-residues.
The bifunctional CMCase and xylanase genes encoding thermostable (rBhcell-xyl) from Bacillus halodurans TSLV1 has been expressed in Escherichia coli. The resulting recombinant E. coli-xyl rBhcell (CMCase 2272 and 910 U L-1 xylanase). The monomer rBhcell-xyl is ~ 62-kDa protein with temperature and pH optimum of 60 ° C and 6.0 with T1 / 2 7.0 and 3.5 hours at 80 ° C for CMCase and xylanase, respectively.
The values of apparent K m (CMC and Birchwood xylan) was 3.8 and https://gentaur.cz/ 3.2 mg mL-1. The catalytic efficiency (k cat / K m) values of xylanase and CMCase was 657 mL and 171 mg-1 min-1, respectively. end-product analysis confirms that rBhcell-xyl are endo-acting enzymes unique to exoglucanase activity.
The rBhcell-xyl a family of enzymes GH5 have catalytic module module and a single carbohydrate binding. RBhcell-xyl action on the cob corn and wheat bran liberated reducing sugars, which can be fermented to bioethanol and fine biochemicals.
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