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Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the digestive system of many vertebrates, where it hydrolyzes proteins.
Crystal structure of Trypsin, a typical serine protease. Serine proteases (or serine endopeptidases) are enzymes that cleave peptide bonds in proteins. Serine serves as the nucleophilic amino acid at the (enzyme's) active site. [1] They are found ubiquitously in both eukaryotes and prokaryotes.
Enteropeptidase (also called enterokinase) is an enzyme produced by cells of the duodenum and is involved in digestion in humans and other animals. Enteropeptidase converts trypsinogen (a zymogen) into its active form trypsin, resulting in the subsequent activation of pancreatic digestive enzymes.
Trypsinogen (/ ˌ t r ɪ p ˈ s ɪ n ə dʒ ə n,-ˌ dʒ ɛ n / [1] [2]) is the precursor form (or zymogen) of trypsin, a digestive enzyme.It is produced by the pancreas and found in pancreatic juice, along with amylase, lipase, and chymotrypsinogen.
Myoglobin sketch Alpha helix. 1958 – Myoglobin was the very first crystal structure of a protein molecule. [2] Myoglobin cradles an iron-containing heme group that reversibly binds oxygen for use in powering muscle fibers, and those first crystals were of myoglobin from the sperm whale, whose muscles need copious oxygen storage for deep dives.
Proteolysis of the zymogen yields an active protein; for example, when trypsinogen is cleaved to form trypsin, a slight rearrangement of the protein structure that completes the active site of the protease occurs, thereby activating the protein.
Ribbon diagram of myoglobin bound to haem (sticks) and oxygen (red spheres) (Ribbon diagrams, also known as Richardson diagrams, are 3D schematic representations of protein structure and are one of the most common methods of protein depiction used today. The ribbon depicts the general course and organization of the protein backbone in 3D and ...
In the 1950s, a serine residue was identified as the catalytic nucleophile of trypsin and chymotrypsin (first purified in the 1930s) [6] by diisopropyl fluorophosphate modification. [7] The structure of chymotrypsin was solved by X-ray crystallography in the 1960s, showing the orientation of the catalytic triad in the active site. [8]