Protein powders are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues.
Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells, and organisms, and transporting molecules from one location to another.
Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity.
Protein powders are essential nutrients for the human body.
They are one of the building blocks of body tissue and can also serve as a fuel source.
As a fuel, proteins provide as much energy density as carbohydrates: 4 kcal (17 kJ) per gram; in contrast, lipids provide 9 kcal (37 kJ) per gram.
The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition.
Proteins are polymer chains made of amino acids linked together by peptide bonds.
During human digestion, proteins are broken down in the stomach to smaller polypeptide chains via hydrochloric acid and protease actions.
This is crucial for the absorption of the essential amino acids that cannot be biosynthesized by the body.
Proteins only exist for a certain period and are then degraded and recycled by the cell’s machinery through the process of protein turnover.
A protein’s lifespan is measured in terms of its half-life and covers a wide range.
They can exist for minutes or years with an average lifespan of 1–2 days in mammalian cells.
Abnormal or misfolded proteins are degraded more rapidly either due to being targeted for destruction or due to being unstable.