title: Low molecular weight chitosans: preparation with the aid of papain and characterization.
abstract: Low molecular weight chitosans (LMWC) of different molecular weight (4.1-5.6 kDa) were obtained by the depolymerization of chitosan using papain (from Carica papaya latex, EC. 3.4.22.2) at optimum conditions of pH 3.5 and 37 degrees C for 1-5 h. Scanning electron microscopy (SEM) showed approximately 15-fold decrease in the particle size after depolymerization. Decrease in the molecular weight was associated with decrease in the degree of acetylation (DA) as evidenced by circular dichroism (CD), FT-IR and solid-state CP-MAS 13C-NMR data. X-ray diffraction pattern revealed slight decrease in the crystallinity index (CrI) whereas the 13C-NMR data showed molecular inhomogeneity. LMWC showed lytic effect towards Bacillus cereus and Escherichia coli more efficiently than native chitosan. The growth inhibitory effect was maximal towards B. cereus, with minimum inhibitory concentration (MIC) of 0.01% (w/v).
authors.affiliation: Department of Biochemistry and Nutrition, Central Food Technological Research Institute, Mysore-570 013, India.
authors.forename: A B
authors.initials: AB
authors.lastname: Vishu Kumar
authors.forename: M C
authors.initials: MC
authors.lastname: Varadaraj
authors.forename: R G
authors.initials: RG
authors.lastname: Lalitha
authors.forename: R N
authors.initials: RN
authors.lastname: Tharanathan
mesh_terms: D000107:Acetylation; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001409:Bacillus cereus / Q000187:drug effects / Q000254:growth & development; D029441:Carica; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000494:pharmacology / Q000648:ultrastructure; D048271:Chitosan; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D010206:Papain / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology; D012997:Solvents; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D000900:Anti-Bacterial Agents; D010446:Peptide Fragments; D012997:Solvents; D002686:Chitin; D048271:Chitosan; D010206:Papain