Non-specific depolymerization of chitosan by pronase and characterization of the resultant products.
Pronase (type XXV serine protease from Streptomyces griseus) efficiently depolymerizes chitosan, a linear beta-->1,4-linked polysaccharide of 2-amino-deoxyglucose and 2-amino-2-N-acetylamino-D-glucose, to low-molecular weight chitosans (LMWC), chito-oligomers (degree of polymerization, 2-6) and monomer. The maximum depolymerization occurred at pH 3.5 and 37 degrees C, and the reaction obeyed Michaelis-Menten kinetics with a Km of 5.21 mg.mL(-1) and Vmax of 138.55 nmoles.min(-1).mg(-1). The molecular mass of the major product, LMWC, varied between 9.0 +/- 0.5 kDa depending on the reaction time. Scanning electron microscopy of LMWC showed an approximately eightfold decrease in particle size and characterization by infrared spectroscopy, circular dichroism, X-ray diffractometry and 13C-NMR revealed them to possess a lower degree of acetylation, hydration and crystallinity compared to chitosan. Chitosanolysis by pronase is an alternative and inexpensive method to produce a variety of chitosan degradation products that have wide and varied biofunctionalities.
Kumar
Acharya B Vishu
AB
Department of Biochemistry and Nutrition, Central Food Technological Research Institute, Mysore, India.
Gowda
Lalitha R
LR
Tharanathan
Rudrapatnam N
RN
D000107:Acetylation; D000117:Acetylglucosamine / Q000737:chemistry; D002247:Carbon Isotopes; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D048271:Chitosan; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D019075:Electrophoresis, Capillary; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D011402:Pronase / Q000737:chemistry* / Q000378:metabolism*; D013055:Spectrophotometry, Infrared; D013305:Streptomyces griseus / Q000201:enzymology; D013696:Temperature; D014783:Viscosity; D014961:X-Ray Diffraction
D002247:Carbon Isotopes; D002686:Chitin; D048271:Chitosan; D011402:Pronase; D000117:Acetylglucosamine