Estimation of Blood Glucose Levels by
Glucose Oxidase Method^13
13.1 Theory
The sugar glucose is an aldohexose and is the most important carbohydrate present
in our body. The bulk of dietary carbohydrate is absorbed mainly as glucose in the
intestine. Glucose is the major source of energy for all the tissues including the brain.
It enters the cell through the influence of insulin and undergoes a series of chemical
reactions to produce energy. It acts as precursor for the synthesis of all other
carbohydrates in the body which have highly specific functions, e.g., glycogen for
storage, ribose in nucleic acid, and galactose in lactose of milk. High levels of
glucose are observed in diabetes mellitus, while decrease in glucose levels occurs in
starvation and hyperinsulinemia.
13.2 Principle........................................
The enzyme GOD oxidizes the plasma glucose to gluconic acid with the
liberation of H 2 O 2 , which is converted to water and oxygen by the enzyme POD.
4-aminoantipyrine, an oxygen acceptor, takes up the oxygen and
together with phenol forms a pink-colored product which can be measured at
520 nm.
GlucoseGOD!Gluconic acidþH 2 O 2
H 2 O 2!
POD
H 2 Oþ½O
½þO 4-aminoantipyrineþPhenol!Chromogen colouredðÞ#Springer Nature Singapore Pte Ltd. 2018
V. Kumar, K. D. Gill,Basic Concepts in Clinical Biochemistry: A Practical Guide,
https://doi.org/10.1007/978-981-10-8186-6_13
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