Biochemistry Practical 3: Glucose Quantification

Biochemistry Practical 3: Glucose Quantification

1. Principle:

• Direct Proportionality: Absorbance (E) is directly proportional to the concentration (C) of the substance.

• Dilution: The photometric method applies the formula: Ct = (Et/Ec) x Cc x V/Vt.

• GOD (Glucose Oxidase): Glucose quantification using the enzyme method relies on the oxidation of glucose by the GOD enzyme.

2. Reaction:

• GOD: Oxidizes glucose to gluconic acid and H2O2.

• QuinoneImine: This substance has a pink color and is used for glucose quantification using the GOD method.

3. Sample:

• Sodium Fluoride Antidiabetic Agent: NaF is added to plasma and serum samples to inhibit glycolysis.

4. Application:

• GOD Method: Can be used to quantify glucose levels in blood.

5. Glucose Concentration:

• Normal Individuals: Fasting blood glucose levels: 4 – 5.6 mmol/L.

• Pre-Diabetic Individuals: Fasting blood glucose levels: 5.6 – 7 mmol/L.

• Diabetic Individuals: Fasting blood glucose levels: above 7 mmol/L.

• Renal Threshold: 9.9 mmol/L. Above this threshold, glucosuria occurs.

• Liver: When blood glucose levels reach 1.2 g/L or higher, the liver reduces glucose production and increases glycogen synthesis.

• HbA1c: Below 6%, patients experience hypoglycemia. Above 6.5%, patients have diabetes.

6. Mechanism of NaF Action:

• NaF: Inhibits the enzyme enolase, thus inhibiting glycolysis.

7. Standard Solution:

• Glucose Standard Solution: Concentration of 5.55 mmol/L.

8. Oral Glucose Tolerance Test:

• Diabetes: Above 11.1 mmol/L.

• Pre-Diabetes: Above 7.8 mmol/L.

9. Factors Influencing Blood Glucose Levels:

• Increase: Excitement, cold, hyperthyroidism, hyperadrenalism, hyperpituitarism.

• Decrease: Prolonged fasting, insulin overdose.

10. Note:

• Elevated Blood Glucose: Can easily lead to glucosuria.

11. Additional Information:

• GOD: Glucose Oxidase.

• Diabetes: Diabetes Mellitus.

• HbA1c: Hemoglobin A1c.

• NaF: Sodium Fluoride.

• Enolase: An enzyme involved in glycolysis.