Glutamate Oxaloacetate Transaminase (aspartate aminotransferase) is an enzyme that is mostly present in the liver cells, kidney, skeletal system, and heart muscles. An increase in the value of GOT-AST in the blood mainly indicates that there is damage to those major organs. Similarly, a lower level of GOT-AST can be due to pregnancy, diabetic ketoacidosis, etc.
Everything that I state below will be based on a semi-auto biochemistry analyzer and can differ from one manufacturer to another.
AST enzyme converts the 2-oxoglutarate, and L-aspartate to L-glutamate and oxaloacetate. The oxaloacetate reacts with NADH in the presence of malate dehydrogenase (MDH) to form NAD. The rate of degradation of NADH to NAD causes a decrease in the absorbance of the light. This is proportional to the activity of the GOT-AST enzyme.
Normally, you can store both the reagents (R1 and R2) at 2-80C till the expiration date. But, once you open the bottle, the lifespan will reduce to about 28 days (at 2-80C ) for R1 and 90 days for R2. Also, for a working solution, the lifespan will be about 14 days.
- Wear an apron and surgical gloves before carrying out the measurement.
- Look for the expiry date of the reagents during purchase and measurement time. Suppliers tend to give you reagent kits with a low expiry interval.
- Bring the reagents and samples to room temperature before you can carry out any measurement.
- Always store reagents in the refrigerator when not in use.
To prepare the working solution, mix R1 and R2 reagents in a ratio of 5:1. After that, add 100 μl of sample to 1000 μl of the prepared working solution. Finally, feed the solution into a semi-auto biochemistry analyzer and get the result.
If the activity of the GOT-AST enzyme is very high (out of range), you need to dilute it with 0.9% NaCl or distilled water in a ratio of 1: y. Then when you get the final result, multiply the value with a dilution factor (1+y).
You will get a decreasing curve in the biochemistry analyzer.