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Non‐specific depolymerization of chitosan by pronase and characterization of the resultant products

2004; Wiley; Volume: 271; Issue: 4 Linguagem: Inglês

10.1111/j.1432-1033.2003.03975.x

1432-1033

Acharya B. Vishu Kumar, Lalitha R. Gowda, Rudrapatnam N. Tharanathan,

Pineapple and bromelain studies

Pronase (type XXV serine protease from Streptomyces griseus ) efficiently depolymerizes chitosan, a linear β→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 °C, and the reaction obeyed Michaelis–Menten kinetics with a K m of 5.21 mg·mL −1 and V max 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 13 C‐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.