Preparation and partial characterization of invertase immobilized on a carboxymethyl-nata-agar- chitosan system

Date

6-2007

Degree

Bachelor of Science in Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Marivic S. Lacsamana

Abstract

Carboxymethyl-nata (CMN) was prepared from nata de coco by pre-treatment with isopropyl alcohol, followed by a two-cycle process of mercerization and etherification. The prepared CMN was a white, fine powder. The moisture content of the CMN was 12.37%. degree of substitution (DS) 0.65 and molecular weight (MW) 939 KDa. The prepared CMN was soluble in 10 M sulfuric acid. 0.1 M and 10 M acetic acid, partially soluble in 0.1 M NaCI, 0.1 M and 10 M NaOH, and insoluble in ethanol and 10 M NaCI. The infrared (IR) analysis of CMN and raw nata indicated conversion of the nata cellulose to carboxymethyl-nata. Invertase was immobilized on a CMN-agar-chitosan system using a 3% sodium polyphosphate solution for cross-linking. The amount of invertase immobilized was 0.5 mg per gram beads. Maximum activity was observed at 30 minutes of cross-linking. Both free and immobilized invertase exhibited maximal activity at 55 T and a sucrose concentration of 0.7 M. Optimum pH achieved for free invertase was 5.0 and that for immobilized invertase was 4.5. The activation energies (Ea) for the free and immobilized enzyme were 0.58 KJ/mol and 16.15 KJ/mol. respectively. The Arrhenius constant (A) for the free and immobilized invertase were 1.31 and 4.41. respectively. The K,, for the free invertase was 1.21 mM and that for the immobilized enzyme was 3.05 mM. Vmax values were 344.83 umol/min and 400 umol/min for the free and immobilized invertase. respectively. The immobilized invertase was found to be relatively stable towards storage, repeated use and continuous use.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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