🔬 1. IFCC Kinetic Method (Standard AST Method)

Primary Reaction (AST enzyme reaction)

L-Aspartate + α-Ketoglutarate
→ Oxaloacetate + L-Glutamate

Indicator (Coupled) Reaction

Oxaloacetate + NADH + H⁺
→ Malate + NAD⁺
(catalyzed by MDH)

LDH is often included to convert pyruvate → lactate, preventing inhibition.

As AST activity increases, NADH decreases, causing a fall in absorbance at 340 nm.

Measurement

• Wavelength: 340 nm

• Mode: Kinetic (rate), ΔA/min

• Rate proportional to AST activity (U/L)