Effect of immobilized neutral protease on the preparation and physicochemical properties of low molecular weight chitosan and chito‐oligomers

Abstract

Neutral protease was immobilized on glutaraldehyde-pretreated N-succinyl chitosan hydrogel beads and the biocatalyst obtained was used for the preparation of low molecular weight chitosan and chito-oligomers with molecular weight of 1.9-23.5 kDa from commercial chitosan. Factors affecting the chitinolytic hydrolysis were described. The degradation was monitored by gel permeation chromatography. The structure of degraded chitosan was characterized by Fourier transform infrared, X-ray diffraction and liquid chromatography-mass spectrometry. Immobilized neutral protease showed optimal depolymerization at pH 5.7 and 508C. The degree of deacetylation of the hydrolysates did not change compared to that of the initial chitosan. The decrease of molecular weight led to transformation of crystal structure but the chemical structures of residues were not modified. The degree of polymerization of chito-oligomers was mainly from 3 to 8. The method allows cyclic procedures of immobilized enzyme and N-succinyl chitosan support utilization, and is suitable for a large-scale production of the low molecular weight chitosan and chito-oligomers free of protein admixtures.

Differences in degradation kinetics for sonolysis, microfluidization and shearing treatments of chitosan

“…However, the acid or alkali depolymerization procedure creates environmental problems 13. The enzymatic method uses chitinase or chitosanase in hydrolyzing higher MW chitin or chitosan, respectively, to smaller MW maerials 15–19. Physical methods are energy‐saving, environmentally friendly and effective, including the ultrasonic method,20–25 the microfluidization method26–28 and mechanical shearing 29–33.…”

Application of Polysaccharide Biopolymer in Petroleum Recovery

“…The high reaction selectivity is helpful to maintain the integral structure of the product, resulting in a more homogeneous distribution of M W . However, the enzymatic treatment is only feasible for the production in lab-scale due to its high cost [ 53 ]. The principle of mechanical methods lies in the physical force to break the chemical bonds between units of Chitin or Chitosan and the physical force can be generated from shearing, ultrasonication, and micro fluidization flow [ 54 , 55 , 56 ].…”

Facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration treatment

“…9 Therefore, it is important to develop a facile method, to manipulate the molecular weight while preserving their integrated structure, that is scaleable to mass production. Degradation methods currently used are: chemical methods, 10 enzymatic methods, 11 physical methods, [12][13][14][15][16][17][18][19][20] and microbial methods. 21 It is difficult to manipulate the molecular weights of the resultant chitosan via chemical methods.…”