Asparagine (Urine)

Asparagine is a protein amino acid. It is non-essential in humans, meaning the body can synthesize it.

Functions of asparagine:

Asparagine is synthesized from aspartate and glutamine. Asparagine has three major functions:

1. incorporation into amino acid sequences of proteins
2. storage form for aspartate (is a required precursor for synthesis of DNA, RNA and ATP)
3. source of amino groups for production of other dispensable amino acids via Transaminases.

Asparagine in proteins is an attachment site for carbohydrates to form collagen assembly, enzymes and cell-cell recognition. Asparagine can be readily converted into aspartate, providing aspartate on demand for many cellular functions. Aspartate can increase cellular energy production by contributing carbon skeletons to the Citric Acid Cycle. Aspartate is also a component of the urea cycle, which removes excess ammonia. The conversion of asparagine to aspartate involves transfer of the extra amino group from asparagine to another keto acid, forming a dispensable amino acid. In this way, asparagine can be a precursor for many amino acids to be produced on demand to meet cell requirements.

Benefits of Asparagine:

Asparagine helps to maintain a balance within the central nervous system, as well as it helps to protect the liver and combats fatigue.

Asparagine and studies on breast cancer:

The link between asparagine and the spread of breast cancer was explored by a multi-center study – published in the journal Nature – that used in vitro and in vivo models of triple-negative breast cancer to expose metastatic drivers.

Among the candidate metastatic drivers evaluated in the study, one stood out—the level of asparagine synthetase expression in a primary tumor. Asparagine synthetase is an enzyme that generates asparagine from aspartate. This finding, from mouse models, was confirmed by an examination of data from breast cancer patients.

Studies have outlined that asparagine is essential for breast cancer spread, and by restricting it, cancer cells stopped invading other parts of the body in mice. So whether a tumor spreads to other parts of the body is dependent on an enzyme called asparagine synthetase.

Our bodies make asparagine, as well as many of the other amino acids that form proteins, and this is one of the enzymes that helps make it. Apparently, the more active this enzyme, the better breast cancer (in this mouse model) is able to spread.

Various media outlets connected asparagus (and other foods) with the above studies and their headlines became quite controversial. The American Institute for Cancer Research commented on the research findings and the media coverage in a blog post that you can read here.

Food sources that contain Asparagine:

- beef

- poultry

- eggs

- fish

- dairy

- whey

- seafood

- asparagus

- legumes

- potatoes

- nuts

- seeds

- soy

- whole grains

Foods low in asparagine include most fruits and vegetables.

References:

• Study of Asparagine 353 in Aminopeptidase A [L]
• Studies on the Utilization of Asparagine by Mouse Leukemia Cells [L]
• Asparagine bioavailability governs metastasis in a model of breast cancer [L]
• Asparagus and Breast Cancer, American Institute for Cancer Research [L]