Types | DnaRegion
|
Roles | Coding
CDS
|
Sequences | BBa_K1104999_sequence (Version 1)
|
Description
Chitinase-63 hydrolyzes radioactive chitin most rapidly at pH 6 and has approximately half-maximal rates for this reaction at pH 4.5 and 7.5.
By contrast, the maximum rate of hydrolysis of the 4-methylumbelliferyl trisaccharide occurs at pH 4 in 0.1 M citrate buffer. The enzyme catalyzes hydrolysis of the trisaccharide derivative over a wide pH range with appreciable activity even in 0.1 M glycine buffer, pH 10.4 (approximately 10% of the rate at pH 4).
Chitinase-63 has a high affinity for the oligosaccharide substrates; Km for the 4-MU trisaccharide is about 0.5 ??M and for the 4-MU disaccharide is about 5 ??M. Higher concentrations produce severe substrate inhibition.
Chitinase-63 is stable when heated at 63 ℃, but is largely inactivated when heated at 80 ℃ for 1 min.
Chitinase-63 produce 4-methylumbelliferone more rapidly from the trisaccharide than from the disaccharide derivative, and both enzymes form more 4-methylumbelliferone than 4-MU- GlcNAc from both the 4-MU trisaccharide and tetrasaccharide. Thus, chitinase-63 might be classified as endochitinases.
Notes
We insert this coding to make E.coli produce Chitinase-63, in order to damage the spore wall of our target --pathogenic fungi, and kill them.
Source
Phillips W. Robbins, Charles Albright, and Barbara Benfield(1988),Cloning and Expression of a Streptomyces plicatus Chitinase (Chitinase-63) in Escherichia coli. Vol. 263, No. 1, Issue of January 5, 443-447.
REFERENCE 1 (sites)
Robbins,P.W., Overbye,K., Albright,C., Benfield,B. and Pero,J. (1992)Cloning and high-level expression of chitinase-encoding gene of Streptomyces plicatus. Gene 111 (1), 69-76.
REFERENCE 2 (bases 1 to 2276)
Delic,I., Robbins,P. and Westpheling,J. (1992) Direct repeat sequences are implicated in the regulation of two Streptomyces chitinase promoters that are subject to carbon catabolite control. Proc. Natl. Acad. Sci. U.S.A. 89 (5), 1885-1889.