Aminopeptidase
Encyclopedia
Aminopeptidase is a zinc
-dependent enzyme
produced and secreted by glands of the small intestine
. It helps the enzymatic digestion of proteins. Additional digestive enzymes produced by these glands include dipeptidases, maltase
, sucrase
, lactase
, and enterokinase.
Aminopeptidases catalyze the cleavage of amino acids from the amino terminus of protein or peptide substrates. They are widely distributed throughout the animal and plant kingdoms and are found in many subcellular organelles, in cytoplasm, and as membrane components. Aminopeptidases are used in essential cellular functions. Many, but not all, of these peptidases are zinc Metalloenzymes.
Some aminopeptidases are monomeric, and others are assemblies of relatively high mass (50 kDa) subunits. CDNA sequences are available for several aminopeptidases and a crystal structure of the open state of human endoplasmic reticulum Aminopeptidase 1 ERAP1 is presented here. Amino acid sequences determined directly or deduced from cDNAs indicate some amino acid sequence homologies in organisms as diverse as Escherichia coli and mammals, particularly in catalytically important residues or in residues involved in metal ion binding.
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
-dependent enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
produced and secreted by glands of the small intestine
Small intestine
The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
. It helps the enzymatic digestion of proteins. Additional digestive enzymes produced by these glands include dipeptidases, maltase
Maltase
Maltase is an enzyme that breaks down the disaccharide maltose. Maltase is an enzyme that catalyzes the hydrolysis of the disaccharide maltose to the simple sugar glucose. This enzyme is found in plants, bacteria, and yeast. Then there is what is called Acid maltase deficiency...
, sucrase
Sucrase
Sucrase is the name given to a number of enzymes that catalyze the hydrolysis of sucrose to fructose and glucose. The enzyme invertase, which occurs more commonly in plants, also hydrolyzes sucrose but by a different mechanism.-Physiology:...
, lactase
Lactase
Lactase , a part of the β-galactosidase family of enzymes, is a glycoside hydrolase involved in the hydrolysis of the disaccharide lactose into constituent galactose and glucose monomers...
, and enterokinase.
Aminopeptidases catalyze the cleavage of amino acids from the amino terminus of protein or peptide substrates. They are widely distributed throughout the animal and plant kingdoms and are found in many subcellular organelles, in cytoplasm, and as membrane components. Aminopeptidases are used in essential cellular functions. Many, but not all, of these peptidases are zinc Metalloenzymes.
Some aminopeptidases are monomeric, and others are assemblies of relatively high mass (50 kDa) subunits. CDNA sequences are available for several aminopeptidases and a crystal structure of the open state of human endoplasmic reticulum Aminopeptidase 1 ERAP1 is presented here. Amino acid sequences determined directly or deduced from cDNAs indicate some amino acid sequence homologies in organisms as diverse as Escherichia coli and mammals, particularly in catalytically important residues or in residues involved in metal ion binding.