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Polymers 2017, 9(5), 174;

pH Dependence of Chitosan Enzymolysis

Biotechnology Institute, College of Chemical Engineering, Xiangtan University, Xiangtan 411105, Hunan, China
Author to whom correspondence should be addressed.
Academic Editors: Naozumi Teramoto and Takashi Tsujimoto
Received: 23 March 2017 / Revised: 5 May 2017 / Accepted: 11 May 2017 / Published: 13 May 2017
(This article belongs to the Special Issue Biodegradable Polymers)
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As a means of making chitosan more useful in biotechnological applications, it was hydrolyzed using pepsin, chitosanase and α-amylase. The enzymolysis behavior of these enzymes was further systematically studied for its effectiveness in the production of low-molecular-weight chitosans (LMWCs) and other derivatives. The study showed that these enzymes depend on ion hydronium (H3O+), thus on pH with a pH dependence fitting R2 value of 0.99. In y = 1.484[H^+] + 0.114, the equation of pH dependence, when [H^+] increases by one, y (k_0/k_m) increases by 1.484. From the temperature dependence study, the activation energy (Ea) and pre-exponential factor (A) were almost identical for two of the enzymes, but a considerable difference was observed in comparison with the third enzyme. Chitosanase and pepsin had nearly identical Ea, but α-amylase was significantly lower. This serves as evidence that the hydrolysis reaction of α-amylase relies on low-barrier hydrogen bonds (LBHBs), which explains its low Ea in actual conditions. The confirmation of this phenomenon was further derived from a similarly considerable difference in the order magnitudes of A between α-amylase and the other two enzymes, which was more than five. Variation of the rate constants of the enzymatic hydrolysis of chitosan with temperature follows the Arrhenius equation. View Full-Text
Keywords: chitosan enzymolysis; parameters; kinetic; pH dependence; activation energy; inhibition chitosan enzymolysis; parameters; kinetic; pH dependence; activation energy; inhibition

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Gohi, B.F.C.A.; Zeng, H.-Y.; Pan, A.D.; Han, J.; Yuan, J. pH Dependence of Chitosan Enzymolysis. Polymers 2017, 9, 174.

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