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Aminopeptidase
Aminopeptidases are enzymes that catalyze the cleavage of amino acids from the N-terminus (beginning), of proteins or peptides. They are found in many organisms; in the cell, they are found in many organelles, in the cytosol (internal cellular fluid), and as membrane proteins. Aminopeptidases are used in essential cellular functions, and are often zinc metalloenzymes, containing a zinc cofactor. Aminopeptidases occur in both water-soluble and membrane-bound forms and can be found both in various cellular compartments and in the extracellular environment (outside of cells). Their broad substrate specificity, their ability to strongly bind to their targets, allows them to remove beginning N-terminal amino acids from almost all unsubstituted oligopeptides. For instance, Aminopeptidase N (AP-N) is particularly abundant in the brush border membranes of the kidney, the small intestine, and the placenta, and is also found in the liver. AP-N is involved in the final digestion of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ERAP1
Endoplasmic reticulum aminopeptidase 1 (ERAP1) is an enzyme that in humans is encoded by the ''ERAP1'' gene. This M1 zinc aminopeptidase is involved in the antigen processing and presentation pathway. ERAP1 is mainly located in the endoplasmic reticulum (ER), where it trims peptides at their N-terminus, adapting them for presentation by MHC class I, MHC class I molecules (MHC-I). Nomenclature Historical names of ERAP1, [HUGO Gene Nomenclature Committee]: * Aminopeptidase regulator of tumour necrosis factor receptor 1 (TNFR1) shedding (ARTS-1) * Adipocyte-derived leucine aminopeptidase (A-LAP) * Puromycin-insensitive leucyl-specific aminopeptidase (PILS-AP) * KIAA0525 * In mice, ER aminopeptidase associated with antigen processing (ERAAP) Biology / Functions Efficient presentation of antigenic peptides by MHC class I molecules provides the key signal for Adaptive immune system, adaptive immune responses by Cytotoxic T cell, cytotoxic (CD8+) T lymphocytes. In the "endogenous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aminopeptidase N
Membrane alanyl aminopeptidase () also known as alanyl aminopeptidase (AAP) or aminopeptidase N (AP-N) is an enzyme that in humans is encoded by the ANPEP gene. Function Aminopeptidase N is located in the small-intestinal and renal microvillar membrane, and also in other plasma membranes. In the small intestine aminopeptidase N plays a role in the final digestion of peptides generated from hydrolysis of proteins by gastric and pancreatic proteases. Its function in proximal tubular epithelial cells and other cell types is less clear. The large extracellular carboxyterminal domain contains a pentapeptide consensus sequence characteristic of members of the zinc-binding metalloproteinase superfamily. Sequence comparisons with known enzymes of this class showed that CD13 and aminopeptidase N are identical. The latter enzyme was thought to be involved in the metabolism of regulatory peptides by diverse cell types, including small intestinal and renal tubular epithelial cells, macrop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leucine Aminopeptidase
Leucyl aminopeptidases (, ''leucine aminopeptidase'', ''LAPs'', ''leucyl peptidase'', ''peptidase S'', ''cytosol aminopeptidase'', ''cathepsin III'', ''L-leucine aminopeptidase'', ''leucinaminopeptidase'', ''leucinamide aminopeptidase'', ''FTBL proteins'', ''proteinates FTBL'', ''aminopeptidase II'', ''aminopeptidase III'', ''aminopeptidase I'') are enzymes that preferentially catalyze the hydrolysis of leucine residues at the N-terminus of peptides and proteins. Other N-terminal residues can also be cleaved, however. LAPs have been found across superkingdoms. Identified LAPs include human LAP, bovine lens LAP, porcine LAP, ''Escherichia coli'' (''E. coli'') LAP (also known as PepA or XerB), and the solanaceous-specific acidic LAP (LAP-A) in tomato (''Solanum lycopersicum''). Enzyme description, structure, and active site The active sites in PepA and in bovine lens LAP have been found to be similar. Shown in the picture below is the proposed model for the active site of LAP-A in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Puromycin-sensitive Aminopeptidase
Cytosol alanyl aminopeptidase (, ''arylamidase'', ''aminopolypeptidase'', ''thiol-activated aminopeptidase'', ''human liver aminopeptidase'', ''puromycin-sensitive aminopeptidase'', ''soluble alanyl aminopeptidase'', ''cytosol aminopeptidase III'', ''alanine aminopeptidase'') is an enzyme. This enzyme catalyses the release of an N-terminal amino acid, preferentially alanine, from a wide range of peptides, amides and arylamides. This puromycin-sensitive enzyme is a Co2+-activated zinc-sialoglycoprotein A sialoglycoprotein is a combination of sialic acid and glycoprotein, which is, itself, a combination of sugar and protein. These proteins often contain one or more sialyl oligosaccharides that are covalently bound to the rest of the molecule. G .... References External links * {{Portal bar, Biology, border=no EC 3.4.11 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exopeptidase
An exopeptidase is any peptidase that catalyzes the cleavage of the terminal (or the penultimate) peptide bond; the process releases a single amino acid, dipeptide or a tripeptide from the peptide chain. Depending on whether the amino acid is released from the amino or the carboxy terminal (N-terminus or C-terminus), an exopeptidase is further classified as an aminopeptidase or a carboxypeptidase, respectively. Thus, an aminopeptidase, an enzyme in the brush border of the small intestine, will cleave a single amino acid from the amino terminal, whereas carboxypeptidase, which is a digestive enzyme present in pancreatic juice, will cleave a single amino acid from the carboxylic end of the peptide. Some examples of exopeptidases include: * Carboxypeptidase A - cleaves C-terminal Phe, Tyr, Trp, or Leu * Carboxypeptidase B - cleaves C-terminal Lys or Arg * Aminopeptidase - cleaves any N-terminal amino acid * Prolinase - cleaves N-terminal Pro from dipeptides * Prolidase - cleav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
N-terminus
The N-terminus (also known as the amino-terminus, NH2-terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide, referring to the free amine group (-NH2) located at the end of a polypeptide. Within a peptide, the amine group is bonded to the carboxylic group of another amino acid, making it a chain. That leaves a free carboxylic group at one end of the peptide, called the C-terminus, and a free amine group on the other end called the N-terminus. By convention, peptide sequences are written N-terminus to C-terminus, left to right (in LTR writing systems). This correlates the translation direction to the text direction, because when a protein is translated from messenger RNA, it is created from the N-terminus to the C-terminus, as amino acids are added to the carboxyl end of the protein. Chemistry Each amino acid has an amine group and a carboxylic group. Amino acids link to one another by peptide bonds which form through a dehydration reaction that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protease
A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalysis, catalyzes proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the formation of new protein products. They do this by cleaving the peptide bonds within proteins by hydrolysis, a reaction where water breaks Covalent bond, bonds. Proteases are involved in numerous biological pathways, including Digestion#Protein digestion, digestion of ingested proteins, protein catabolism (breakdown of old proteins), and cell signaling. In the absence of functional accelerants, proteolysis would be very slow, taking hundreds of years. Proteases can be found in all forms of life and viruses. They have independently convergent evolution, evolved multiple times, and different classes of protease can perform the same reaction by completely different catalytic mechanisms. Classification Based on catalytic residue Proteases can be classified into seven broad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metalloprotein
Metalloprotein is a generic term for a protein that contains a metal ion cofactor. A large proportion of all proteins are part of this category. For instance, at least 1000 human proteins (out of ~20,000) contain zinc-binding protein domains although there may be up to 3000 human zinc metalloproteins. Abundance It is estimated that approximately half of all proteins contain a metal. In another estimate, about one quarter to one third of all proteins are proposed to require metals to carry out their functions. Thus, metalloproteins have many different functions in cells, such as storage and transport of proteins, enzymes and signal transduction proteins, or infectious diseases. The abundance of metal binding proteins may be inherent to the amino acids that proteins use, as even artificial proteins without evolutionary history will readily bind metals. Most metals in the human body are bound to proteins. For instance, the relatively high concentration of iron in the human body ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CDNA
In genetics, complementary DNA (cDNA) is DNA that was reverse transcribed (via reverse transcriptase) from an RNA (e.g., messenger RNA or microRNA). cDNA exists in both single-stranded and double-stranded forms and in both natural and engineered forms. In engineered forms, it often is a copy (replicate) of the naturally occurring DNA from any particular organism's natural genome; the organism's own mRNA was naturally transcribed from its DNA, and the cDNA is reverse transcribed from the mRNA, yielding a duplicate of the original DNA. Engineered cDNA is often used to express a specific protein in a cell that does not normally express that protein (i.e., heterologous expression), or to sequence or quantify mRNA molecules using DNA based methods (qPCR, RNA-seq). cDNA that codes for a specific protein can be transferred to a recipient cell for expression as part of recombinant DNA, often bacterial or yeast expression systems. cDNA is also generated to analyze transcriptomic pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
