Glutamine is an amino acid synthesized in the muscle that plays major roles in protein synthesis, acid-base balance, anabolic processes and is utilized for cellular energy and as a carbon source. It contains an uncharged amide as a side chain, and is a non-essential amino acid. It is formed by condensation of glutamate and ammonia, but plays an important role in biological processes such as protein synthesis, regulation of acid-balance in mammalian kidneys and cell growth. It is the main source of nitrogen for the synthesis of nucleotides and hexosamine by cells. It is used in treatment of injury, trauma, burns, and also as a supplement for muscle growth and post-surgery healing.

Glutamine Assay Kit provides a simple, reproducible, and sensitive tool of measuring glutamine concentration in plasma, serum, cell lysates, urine, and other biological liquid samples. This assay employs a coupled enzymatic reaction system that combines multiple steps. Initially, glutaminase converts glutamine to glutamate and NH₃. L-glutamate oxidase catalyzes the conversion of the generated glutamate and oxygen into α-ketoglutarate, ammonia, and hydrogen peroxide. Peroxidase then catalyzes the reaction of hydrogen peroxide with the Colorimetric Probe to form a pink-colored product. The optical density measured at 515 nm is directly proportional to the concentration of glutamine present in the sample.

• Microplate reader capable of measuring absorbance at 515 nm
• Precision pipettes to deliver 2 µL to 1 mL volumes
• Tubes to prepare sample dilutions
• Incubator at 37°C
• 50 mL conical tubes
• Multi-channel pipettes to deliver 20 µL to 200 µL volumes
• MilliQ water or another type of double distilled water (ddH₂O)
• 10 kDa cut-off spin filter

1. Add 50 µL of the diluted Glutamine standards or samples to the 96-well microtiter plate.
2. Add 30 µL Reaction Mix to each standard and one half of the paired sample wells, mix thoroughly.
3. Add 30 µL of Hydrolysis Buffer to other half of the paired sample wells. Carefully shake the plate for a few seconds to mix well.
4. Incubate the plate for 30 minutes at 37°C with mixing in the dark.
5. Add 50 µL of Working Solution to each well. Incubate the plate at 37°C for 60 minutes with mixing in the dark.
6. Measure the absorbance at 515 nm using a plate reader.