What is the most abundant amino acid present in tissue and plasma?

The correct answer is glutamine, which is the most abundant amino acid found in both tissue and plasma. Glutamine plays a crucial role in various physiological processes, serving as a key substrate for the synthesis of proteins and nucleotides. It acts as a primary nitrogen donor in the biosynthesis of amino acids and nucleotides, making it vital for cellular function and energy metabolism.

In addition to its roles in protein synthesis, glutamine is important for maintaining acid-base balance, supporting immune function, and acting as a fuel source for rapidly dividing cells, such as lymphocytes and enterocytes. Given its high concentration in the bloodstream and its significance in various metabolic pathways, glutamine is typically the most abundant amino acid in the body.

While other amino acids such as glutamate, alanine, and serine also have important roles, they do not reach the same levels of concentration as glutamine in plasma and tissues. Each of these amino acids contributes to specific metabolic pathways but is outnumbered by glutamine in terms of overall abundance in the body's compartments.