A protease is an enzyme that 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 bonds. Proteases are involved in many biological functions, including digestion of ingested proteins, protein catabolism, and cell signaling.
DD-transpeptidase is a bacterial enzyme that catalyzes the transfer of the R-L-aca-D-alanyl moiety of R-L-aca-D-alanyl-D-alanine carbonyl donors to the γ-OH of their active-site serine and from this to a final acceptor. It is involved in bacterial cell wall biosynthesis, namely, the transpeptidation that crosslinks the peptide side chains of peptidoglycan strands.
An exopeptidase is any peptidase that catalyzes the cleavage of the terminal 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, 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.
The peptidyl transferase is an aminoacyltransferase as well as the primary enzymatic function of the ribosome, which forms peptide bonds between adjacent amino acids using tRNAs during the translation process of protein biosynthesis. The substrates for the peptidyl transferase reaction are two tRNA molecules, one bearing the growing peptide chain and the other bearing the amino acid that will be added to the chain. The peptidyl chain and the amino acids are attached to their respective tRNAs via ester bonds to the O atom at the CCA-3' ends of these tRNAs. Peptidyl transferase is an enzyme that catalyzes the addition of an amino acid residue in order to grow the polypeptide chain in protein synthesis. It is located in the large ribosomal subunit, where it catalyzes the peptide bond formation. It is composed entirely of RNA. The alignment between the CCA ends of the ribosome-bound peptidyl tRNA and aminoacyl tRNA in the peptidyl transferase center contribute to its ability to catalyze these reactions. This reaction occurs via nucleophilic displacement. The amino group of the aminoacyl tRNA attacks the terminal carboxyl group of the peptidyl tRNA. Peptidyl transferase activity is carried out by the ribosome. Peptidyl transferase activity is not mediated by any ribosomal proteins but by ribosomal RNA (rRNA), a ribozyme. Ribozymes are the only enzymes which are not made up of proteins, but ribonucleotides. All other enzymes are made up of proteins. This RNA relic is the most significant piece of evidence supporting the RNA World hypothesis.
A carboxypeptidase is a protease enzyme that hydrolyzes (cleaves) a peptide bond at the carboxy-terminal (C-terminal) end of a protein or peptide. This is in contrast to an aminopeptidases, which cleave peptide bonds at the N-terminus of proteins. Humans, animals, bacteria and plants contain several types of carboxypeptidases that have diverse functions ranging from catabolism to protein maturation. At least two mechanisms have been discussed.
Protein metabolism denotes the various biochemical processes responsible for the synthesis of proteins and amino acids (anabolism), and the breakdown of proteins by catabolism.
Carboxypeptidase B is a carboxypeptidase that preferentially acts upon basic amino acids, such as arginine and lysine. This serum enzyme is also responsible for rapidly metabolizing the C5a protein into C5a des-Arg, with one less amino acid.
Urocanase is the enzyme that catalyzes the second step in the degradation of histidine, the hydration of urocanate into imidazolonepropionate.
Carboxypeptidase A usually refers to the pancreatic exopeptidase that hydrolyzes peptide bonds of C-terminal residues with aromatic or aliphatic side-chains. Most scientists in the field now refer to this enzyme as CPA1, and to a related pancreatic carboxypeptidase as CPA2.
In enzymology, an aminoacylase (EC 3.5.1.14) is an enzyme that catalyzes the chemical reaction
A 2-oxoisovalerate dehydrogenase subunit alpha, mitochondrial is an enzyme that in humans is encoded by the BCKDHA gene.
Carboxypeptidase N catalytic chain is an enzyme that in humans is encoded by the CPN1 gene.
Carboxypeptidase A6 (CPA6) is a metallocarboxypeptidase enzyme that in humans is encoded by the CPA6 gene. It is highly expressed in the adult mouse olfactory bulb and is broadly expressed in the embryonic brain and other tissues.
Peptidyl-dipeptidase Dcp (EC 3.4.15.5, dipeptidyl carboxypeptidase (Dcp), dipeptidyl carboxypeptidase) is a metalloenzyme found in the cytoplasm of bacterium E. Coli responsible for the C-terminal cleavage of a variety of dipeptides and unprotected larger peptide chains. The enzyme does not hydrolyze bonds in which P1' is Proline, or both P1 and P1' are Glycine. Dcp consists of 680 amino acid residues that form into a single active monomer which aids in the intracellular degradation of peptides. Dcp coordinates to divalent zinc which sits in the pocket of the active site and is composed of four subsites: S1’, S1, S2, and S3, each subsite attracts certain amino acids at a specific position on the substrate enhancing the selectivity of the enzyme. The four subsites detect and bind different amino acid types on the substrate peptide in the P1 and P2 positions. Some metallic divalent cations such as Ni+2, Cu+2, and Zn+2 inhibit the function of the enzyme around 90%, whereas other cations such as Mn+2, Ca+2, Mg+2, and Co+2 have slight catalyzing properties, and increase the function by around 20%. Basic amino acids such as Arginine bind preferably at the S1 site, the S2 site sits deeper in the enzyme therefore is restricted to bind hydrophobic amino acids with phenylalanine in the P2 position. Dcp is divided into two subdomains (I, and II), which are the two sides of the clam shell-like structure and has a deep inner cavity where a pair of histidine residues bind to the catalytic zinc ion in the active site. Peptidyl-Dipeptidase Dcp is classified like Angiotensin-I converting enzyme (ACE) which is also a carboxypeptidase involved in blood pressure regulation, but due to structural differences and peptidase activity between these two enzymes they had to be examined separately. ACE has endopeptidase activity, whereas Dcp strictly has exopeptidase activity based on its cytoplasmic location and therefore their mechanisms of action are differentiated. Another difference between these enzymes is that the activity of Peptidyl-Dipeptidase Dcp is not enhanced in the presence of chloride anions, whereas chloride enhances ACE activity.
Lysosomal Pro-Xaa carboxypeptidase is an enzyme. This enzyme catalyses the following chemical reaction
Lysine carboxypeptidase is an enzyme. This enzyme catalyses the following chemical reaction:
Gly-Xaa carboxypeptidase is an enzyme. This enzyme catalyses the following chemical reaction
Metallocarboxypeptidase D is an enzyme. This enzyme catalyses the following chemical reaction
Carboxypeptidase D can refer to one of several enzymes. A family of serine carboxypeptidases includes is an enzyme. This enzyme has an optimal pH of 4.5-6.0, is inhibited by diisopropyl fluorophosphate, and catalyses the following chemical reaction
C20orf96 is a protein-coding gene in humans. It codes for an unknown protein known as uncharacterized protein C20orf96, predicted to be a nuclear protein. The function and biological processes of the gene is not well understood by the scientific community yet.
