Rat brain apotransketolase: activation and inactivation

Area of Science:

• Biochemistry
• Enzymology

Background:

• Apotransketolase is crucial for carbohydrate metabolism.
• Thiamine diphosphate is an essential cofactor for transketolase.
• Previous studies faced challenges in determining Michaelis constants for this enzyme.

Purpose of the Study:

• To investigate the kinetic behavior of rat brain apotransketolase with thiamine diphosphate.
• To explore the existence of multiple forms of apotransketolase.
• To understand how storage affects enzyme activation.

Main Methods:

• Kinetic analysis of apotransketolase-thiamine diphosphate interaction.
• Investigating enzyme forms under varying storage conditions.

Main Results:

• Rat brain apotransketolase exhibits multiple forms with differing reactivities towards thiamine diphosphate.
• A portion of the apoenzyme undergoes an irreversible change, becoming unactivable.
• The proportion of rapidly reacting apoenzyme decreases with prolonged or improper storage.

Conclusions:

• The heterogeneity of apotransketolase contributes to difficulties in determining Michaelis constants.
• Enzyme storage conditions significantly influence its kinetic properties and activation potential.