You are watching: Protein is the only macronutrient that contains nitrogen
What Is Protein?
Proteins are large, complex molecules that room essential contents of all human being tissues (e.g., bones, blood, hormones, enzymes, antibodies). Proteins contain the facets carbon, hydrogen, and also oxygen simply as carbohydrates and lipids do, yet proteins space the only macronutrient that has nitrogen. Proteins are macromolecules composed of amino acids. Amino mountain are generally called the "building blocks" that protein. Amino acids contain five elements (Figure \(\PageIndex1\)). Every amino acid is composed of a central carbon atom (C) connected to a next chain (R), a hydrogen (H), a nitrogen-containing amino team (NH2), and a carboxylic acid team (COOH) — therefore the surname “amino acid”. Amino acids differ native each various other by which particular side chain (R) is bonded to the carbon center. The next chain of one amino acid can be as simple as one hydrogen external inspection to the carbon center (glycine; figure \(\PageIndex2a\)) or more facility like leucine (Figure \(\PageIndex2b\)).
| Histidine | Alanine |
| Isoleucine | Arginine* |
| Leucine | Asparagine |
| Lysine | Aspartic acid |
| Methionine | Cysteine* |
| Phenylalanine | Glutamic acid |
| Threonine | Glutamine* |
| Tryptophan | Glycine* |
| Valine | Proline* |
| Serine | |
| Tyrosine* | |
Building Proteins with Amino acids (Protein Synthesis)
A protein is composed of multiple amino acids. Various proteins room produced because there are 20 amino mountain that have the right to be linked in distinctive sequences. Each amino acid is linked to the following amino mountain by a distinct chemical bond referred to as a peptide shortcut (Figure \(\PageIndex3\)). The peptide shortcut forms in between the carboxylic acid group of one amino acid and the amino team of another, publication a molecule that water.When amino acids join together, they form peptides and are nalifwynnfoundation.org based on how numerous amino acids room in the peptide. Because that example, a dipeptidecontains2 amino acids, a tripeptide contains3 amino acids, one oligopeptide has4-9 amino acids, and a polypeptide consists of 10 or an ext amino acids.