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The main alcohol dehydrogenase in yeast is larger than the human one, consisting of four rather than just two subunits. It also contains zinc at its catalytic site. Together with the zinc-containing alcohol dehydrogenases of animals and humans, these enzymes from yeasts and many bacteria form the family of "long-chain"-alcohol dehydrogenases.
Tryptophan synthase or tryptophan synthetase is an enzyme (EC 4.2.1.20) that catalyzes the final two steps in the biosynthesis of tryptophan. [1] [2] It is commonly found in Eubacteria, [3] Archaebacteria, [4] Protista, [5] Fungi, [6] and Plantae. [7] However, it is absent from Animalia. [8] It is typically found as an α2β2 tetramer.
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.
Structure of the trp operon. The trp operon is a group of genes that are transcribed together, encoding the enzymes that produce the amino acid tryptophan in bacteria. The trp operon was first characterized in Escherichia coli, and it has since been discovered in many other bacteria. [1]
The pathway for the synthesis of serotonin from tryptophan. In animals and humans, serotonin is synthesized from the amino acid L-tryptophan by a short metabolic pathway consisting of two enzymes, tryptophan hydroxylase (TPH) and aromatic amino acid decarboxylase (DDC), and the coenzyme pyridoxal phosphate. The TPH-mediated reaction is the rate ...
Tryptophan 2,3-dioxygenase is a heme-containing cytosolic enzyme encoded by gene TDO2. [5] Crystallographic studies of Xanthomonas campestris TD) [13] and Ralstonia metallidurans TDO) [16] have revealed that their structures are essentially identical and are intimately associated homotetrameric enzymes. [17]
The main substrates of chymotrypsin are peptide bonds in which the amino acid N-terminal to the bond is a tryptophan, tyrosine, phenylalanine, or leucine. Like many proteases, chymotrypsin also hydrolyses amide bonds in vitro, a virtue that enabled the use of substrate analogs such as N-acetyl-L-phenylalanine p-nitrophenyl amide for enzyme assays.
It is an enzyme that catalyzes the breakdown of acetylcholine and some other choline esters that function as neurotransmitters: acetylcholine + H 2 O = choline + acetate It is found at mainly neuromuscular junctions and in chemical synapses of the cholinergic type, where its activity serves to terminate cholinergic synaptic transmission .