The Experts below are selected from a list of 21 Experts worldwide ranked by ideXlab platform
William L. Mock - One of the best experts on this subject based on the ideXlab platform.
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X-Pro Dipeptidase (eukaryotes)
Handbook of Proteolytic Enzymes, 2004Co-Authors: William L. MockAbstract:Publisher Summary This chapter discusses the activity, specificity and structural chemistry of X-Pro Dipeptidase (XPD). A Dipeptidase showing specificity for C-terminal proline was originally obtained from mammalian intestine and designated as prolidase. It was isolated, shown to be a metalloenzyme and characterized for substrate preference. The enzyme has been found in a variety of tissues and in bacteria, and is variously known as Xaa-Pro Dipeptidase, X-Pro Dipeptidase, proline Dipeptidase, imidoDipeptidase or peptidase D. XPD from a number of sources has been shown to exist in solution as a dimer of 55 kDa subunits, each of which consists of an identical single chain. An essential Arg has been identified at the active site by chemical modification. The human enzyme has been sequenced, and primary structures are also known for the mouse and the bacterial counterparts. XPD has been shown to cleave only the trans rotamer of the acyl-proline peptide linkage within its substrates. The active site evidently contains a catalytic metal ion that is especially Lewis-acidic. Activation of the dipeptide scissile linkage by chelative binding of the substrate N-terminus to a metal ion is indicated from specificity studies.
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Xaa-Pro Dipeptidase (Bacteria)
Handbook of Proteolytic Enzymes, 2004Co-Authors: William L. MockAbstract:Publisher Summary This chapter discusses the activity, specificity and structural chemistry of X-Pro Dipeptidase (XPD). A Dipeptidase showing specificity for C-terminal proline has been found in a variety of prokaryotes. An enzyme of similar specificity has been characterized from mammalian sources. The latter enzyme has received more extensive mechanistic investigation. The other names that have been used for this enzyme include prolidase, imidoDipeptidase, proline Dipeptidase, peptidase D, γ-peptidase, pepQ and X-Pro Dipeptidase. The reaction of this enzyme involves the hydrolysis of Xaa-fPro dipeptides, although some members are described as cleaving other dipeptides or even tripeptides. The enzyme is active at neutral pH. Extensive specificity studies have been carried out with pig kidney XPD. Several sequences are available. A number of the enzymes have been purified and characterized to varying extents. The active enzyme commonly exists as a homodimer. A crystallographic structure for the homologous aminopeptidase P from E. coli is available. It is found that the enzyme is commonly described as a Mn2+-activated enzyme.
Minoru Harada - One of the best experts on this subject based on the ideXlab platform.
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High performance liquid chromatographic determination of peptidase activity toward proline-containing peptides
Analytica Chimica Acta, 1997Co-Authors: Minoru HaradaAbstract:Abstract This review presents a simple and highly reproducible method for the determination of proline-containing peptides by high performance liquid chromatography (HPLC). Since proline residues exert unique structural constraints on peptide chains, proline-specific peptidases are required for the hydrolysis of peptides containing this imino acid. The following peptidases are discussed: X-Pro amino peptidase, X-Pro Dipeptidase, dipeptidyl peptidase IV, lysosomal Pro-X carboxypeptidase, membrane Pro-X carboxypeptidase, dipeptidyl peptidase II, prolyl oligopeptidase, and prolyl iminopeptidase.
Amy M. Grunden - One of the best experts on this subject based on the ideXlab platform.
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Xaa-Pro Dipeptidase (Archaea)
Handbook of Proteolytic Enzymes, 2004Co-Authors: Michael W. W. Adams, Amy M. GrundenAbstract:Publisher Summary This chapter examines the structural chemistry and the biological aspects of X-Pro Dipeptidase. P. furiosus X-Pro Dipeptidase was identified based on its ability to hydrolyze the dipeptide Met┼Pro using a colorimetric ninhydrin assay method. Catalytic parameters using Met-Pro as the substrate along with the physical properties of the enzyme are presented. Substrate specificity assays indicate that P. furiosus Dipeptidase has significant catalytic activity only with dipeptides that have Pro at the C-terminus. Furthermore, the nature of the amino acid residue in the N-terminal position is crucial in determining the activity of the enzyme, as only substrates containing nonpolar amino acids in the N-terminal position are hydrolyzed at significant rates. The native and the recombinant forms of the enzyme had virtually indistinguishable catalytic properties. P. furiosus X-Pro Dipeptidase exhibits the maximal activity at pH 7.0 at a temperature of 100°C, with negligible activity at temperatures below 40°C. The enzyme is extremely thermostable, although the extent depends on the protein concentration. The native form of the enzyme retains full activity even after 12-hour incubation at 100°C.
Michael W. W. Adams - One of the best experts on this subject based on the ideXlab platform.
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Xaa-Pro Dipeptidase (Archaea)
Handbook of Proteolytic Enzymes, 2004Co-Authors: Michael W. W. Adams, Amy M. GrundenAbstract:Publisher Summary This chapter examines the structural chemistry and the biological aspects of X-Pro Dipeptidase. P. furiosus X-Pro Dipeptidase was identified based on its ability to hydrolyze the dipeptide Met┼Pro using a colorimetric ninhydrin assay method. Catalytic parameters using Met-Pro as the substrate along with the physical properties of the enzyme are presented. Substrate specificity assays indicate that P. furiosus Dipeptidase has significant catalytic activity only with dipeptides that have Pro at the C-terminus. Furthermore, the nature of the amino acid residue in the N-terminal position is crucial in determining the activity of the enzyme, as only substrates containing nonpolar amino acids in the N-terminal position are hydrolyzed at significant rates. The native and the recombinant forms of the enzyme had virtually indistinguishable catalytic properties. P. furiosus X-Pro Dipeptidase exhibits the maximal activity at pH 7.0 at a temperature of 100°C, with negligible activity at temperatures below 40°C. The enzyme is extremely thermostable, although the extent depends on the protein concentration. The native form of the enzyme retains full activity even after 12-hour incubation at 100°C.
William H. Simmons - One of the best experts on this subject based on the ideXlab platform.
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Xaa-Pro Aminopeptidase (Prokaryote)
Handbook of Proteolytic Enzymes, 2012Co-Authors: William H. SimmonsAbstract:Publisher Summary This chapter elaborates the structural chemistry and the biological aspects of X-Pro aminopeptidase (XProAP). E. coli XProAP removes the N-terminal residue from peptides that have a proline residue in the penultimate position. The PI' proline can be substituted with 3,4-dehydroproline, but not with trans-4-hydroxyproline. The enzyme can accommodate a variety of amino acids including proline in both the PI and P2 positions. It is stereospecific and requires L-amino acids in PI and L-proline in PI. Xaaj-Pro dipeptides are cleaved more slowly than larger peptides. Only the trans form of the Xaa–Pro bond is hydrolyzed. The first nucleotide and deduced amino acid sequences for XProAP were determined for E. coli type II enzyme. E. coli enzyme is 440 amino acids long, with an Mr of 49,684. Monomers form very stable dimers and dimers form tetramers at biologically significant concentrations. XProAP is possibly involved in intracellular protein turnover by hydrolyzing Xaa-Pro-Y peptides resistant to other peptidases. Mutants of Salmonella typhimurium lacking this enzyme have a much reduced ability to produce free proline during starvation-induced protein breakdown. The structurally related X-Pro Dipeptidase has been found in bacteria and is specific for Xaa-Pro dipeptides.
