NANP Board Practice Exam

Which amino acid is considered the most abundant in whole blood?

1. Alanine

2. Glutamine

3. Glycine

4. Lysine

The correct answer is: Glutamine

The most abundant amino acid in whole blood is glutamine. It plays a crucial role in various physiological processes, including protein synthesis, nitrogen transport, and serving as a fuel source for certain cells, particularly in the immune and gastrointestinal systems. Glutamine is particularly critical in maintaining the integrity of the gut lining and immune function, making its presence in the bloodstream essential for overall health. Other amino acids listed, while important, do not surpass glutamine in abundance under normal physiological conditions. Alanine, for example, is involved in energy production and gluconeogenesis, but its concentration is lower compared to glutamine. Glycine serves as a building block for proteins and is important in the synthesis of various biomolecules, but again, does not occur as frequently in blood. Lysine is essential for protein synthesis and various metabolic processes but is less abundant in circulating blood compared to glutamine. Thus, glutamine's predominant role and presence in whole blood solidify its status as the most abundant amino acid.