Peptidases aspartic peptidase

Serine peptidase Metaiio peptidase Cysteine peptidase Aspartic peptidase Giutamic peptidase Threonine peptidase Asparagine peptidase... 

Aspartic peptidases bind and activate water via two aspartic acid residues. 

Peptidases have been classified by the MEROPS system since 1993 [2], which has been available viatheMEROPS database since 1996 [3]. The classification is based on sequence and structural similarities. Because peptidases are often multidomain proteins, only the domain directly involved in catalysis, and which beais the active site residues, is used in comparisons. This domain is known as the peptidase unit. Peptidases with statistically significant peptidase unit sequence similarities are included in the same family. To date 186 families of peptidase have been detected. Examples from 86 of these families are known in humans. A family is named from a letter representing the catalytic type ( A for aspartic, G for glutamic, M for metallo, C for cysteine, S for serine and T for threonine) plus a number. Examples of family names are shown in Table 1. There are 53 families of metallopeptidases (24 in human), 14 of aspartic peptidases (three of which are found in human), 62 of cysteine peptidases (19 in human), 42 of serine peptidases (17 in human), four of threonine peptidases (three in human), one of ghitamicpeptidases and nine families for which the catalytic type is unknown (one in human). It should be noted that within a family not all of the members will be peptidases. Usually non-peptidase homologues are a minority and can be easily detected because not all of the active site residues are conserved. 

It is recommended that a well-characterized peptidase should have a trivial name. Although not rigidly adhered to, there is a different suffix for each catalytic type, metallopeptidases names end with lysin , aspartic peptidases with pepsin , cysteine pqrtidase with ain and serine peptidases with in . 

Inhibitors which interact only with peptidases of one catalytic type include pepstatin (aspartic peptidases) E64 (cysteine peptidases from clan CA) diisopropyl fluorophosphates (DFP) and phenylmethane sulfonyl-fluoride (PMSF) (serine peptidases). Bestatin is a useful inhibitor of aminopeptidases. 

Enzymes of the pepsin family rarely catalyze the hydrolysis of esters, with the exceptions of, for example, esters of L-/3-penicillactic acid and some sulfinic acid esters. Under suitable conditions, i. e., low pH, high enzyme concentration, and formation of an insoluble peptide, aspartic peptidases are able to catalyze the synthesis of peptides [71] [72],... 

Like aspartic peptidases, metallopeptidases act by activating a H20 molecule, and they do not form a covalent intermediate with the substrate. Here, the activation of a H20 molecule is mediated by a residue that acts as general base (e.g., Glu, His, Lys, Arg, or Tyr), with a divalent cation (usually Zn2+ but sometimes Co2+ or Mn2+) perhaps also contributing. The major role of the metal cation, however, is to act as an electrophilic catalyst by coordinating the carbonyl (or phosphoryl) O-atom in the substrate and orienting the latter for nucleophilic attack by the HO ion generated from H20 by the general base. 

Dash C, Kulkarni A, Dunn B, Rao M. 2003. Aspartic peptidase inhibitors implications in drug development. Grit Rev Biochem Mol Biol 38 89-119. 

This method is compatible with many functional groups and shows considerable selectivity. Phosphonic acid esters may be cleaved in the presence of carboxylic acid esters, and phosphonate methyl esters are cleaved approximately 25 times faster than the isopropyl esters. For example, the phosphonate methyl ester of the hexapeptide analogue 78 was cleaved with TMSBr to give the aspartic peptidase inhibitor 79 in 64% yield (Scheme 28). 66 ... 

Aspartic peptidases, 365 Atmospheric pressure chemical ionization (APCI), used with LC/MS ATR-FTIR. see Attenuated total reflection Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), trans fatty acids, 505-511 Autoxidation. see also Oxidation discussed, 535 of lipids, 558, 627 prevention of, 558... 

Aspartic peptidases have so far been described for all endopeptidases. Unfortunately, the tertiary structure has only been elucidated for four families. Endopeptidases of the family A1 consist of two lobes, with the active site between them. One lobe has been derived from the other by gene duplication. In the active site each lobe, with very similar three-dimensional structures, bears one Asp residue of the catalytic dyad. It is interesting to note that the crystal structure of retropepsin from family A2 of clan AA showed a single lobe with one catalytic Asp residue with structural similarity to one lobe of the pepsin from family Al. Retropepsin is only active as a homodimer forming the catalytic site between the two monomeric molecules. There is evidence that the peptidases of families Al and A2 have evolved from a common ancestor. Unfortunately, a number of other families could not yet been assigned to any clan. 

Dunn, B.M. (2002) Structure and mechanism of the pepsin-like family of aspartic peptidases. Chemical Reviews, 102 (12), 4431 458. 

Typical examples of enzymes involved in food applications are cholinesterase for organophosphorous and carbamate pesticide analysis tyrosinase or laccase for analysis of phenols, quinones, and related compounds glucose oxidase for sugar content analysis, carboxyl esterase, alcohol oxidase, carboxypeptidase, L-aspartase, peptidase, aspartate... 

Peptidase Aspartate deaminase L-glutamate oxidase Amperometry 0-1 mmol L 20 pmol L 8 [55]... 

In Merops, the peptidase database, release 9.5, there are 16 families of the aspartic peptidases distributed between vertebrates, fungi, plants, protozoa, viruses, and prokaryotes (Horimoto et al. 2009). Structurally, aspartic peptidases are bilobal enzymes, each lobe contributing with a catalytic Asp residue, with an extended active site cleft localized between the two lobes of the molecule. The presence and position of disulfide bridges are another conserved feature of aspartic peptidases. All or most aspartate peptidases are endopeptidases. In prokaryotes, they are detected in archaea and bacteria. One example is the thermopsin, which is a thermostable acid protease fi-om the archaea Sulfolobus acidocaldarius (A5 family, EC 3.4.23.42) (Dash et al. 2003). The enzyme shows a broad protein substrate... 

Horimoto Y, Dee DR, Yada RY (2009) Multifunctional aspartic peptidase prosegments. N Biotechnol 25 318-324... 

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