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| Enzyme Name | | Swiss-prot | KEGG |
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| P05994 |
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| Protein name | Papaya proteinase 4 | glycyl endopeptidasepapaya peptidase Bpapaya proteinase IVglycine-specific proteinasechymopapainPapaya proteinase 4PPIVchymopapain M |
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| Synonyms | EC 3.4.22.25Papaya proteinase IVPPIVPapaya peptidase BGlycyl endopeptidase |
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| Swiss-prot:Accession Number | P05994 |
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| Entry name | PAPA4_CARPA |
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| Activity | Preferential cleavage: Gly-|-Xaa, in proteins and in small molecule substrates. |
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| Subunit |
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| Subcellular location |
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| Cofactor |
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| Substrates | Products | intermediates |
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| KEGG-id | C00017 | C00012 | C00001 | C00017 | C00012 | I00153 | I00154 | I00155 |
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| Compound | Protein | Peptide | H2O | Protein | Peptide | Peptidyl-Cys-tetrahedral-intermediate (with previous peptide) | Acyl-enzyme(Peptidyl-Cys-acyl group) | Peptidyl-Cys-tetrahedral-intermediate |
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| Type | peptide/protein | peptide/protein | H2O | peptide/protein | peptide/protein |
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| 1gecE |  | Unbound | Unbound |
| Unbound | Unbound | Unbound | Intermediate-analogue:PHQ-LEU-VAL-GLY-0HQ(chain I) | Unbound |
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| Active-site residues | | resource |
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| Swiss-prot;P05994 | | pdb | Catalytic residues | Main-chain involved in catalysis |
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| 1gecE | | GLN 19;CYS 25;HIS 159;ASN 179
| CYS 25
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| References for Catalytic Mechanism | | References | Sections | No. of steps in catalysis |
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| [1] | p.814-818 |
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| references | | [1] |
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| PubMed ID | 8010964 |
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| Journal | Biochem J |
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| Year | 1994 |
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| Volume | 300 |
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| Pages | 805-20 |
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| Authors | Thomas MP, Topham CM, Kowlessur D, Mellor GW, Thomas EW, Whitford D, Brocklehurst K |
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| Title | Structure of chymopapain M the late-eluted chymopapain deduced by comparative modelling techniques and active-centre characteristics determined by pH-dependent kinetics of catalysis and reactions with time-dependent inhibitors: the Cys-25/His-159 ion-pair is insufficient for catalytic competence in both chymopapain M and papain. |
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| [2] |
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| Comments | X-ray crystallography (2.1 Angstroms) |
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| PubMed ID | 7548082 |
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| Journal | Biochemistry |
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| Year | 1995 |
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| Volume | 34 |
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| Pages | 13190-5 |
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| Authors | O'Hara BP, Hemmings AM, Buttle DJ, Pearl LH |
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| Title | Crystal structure of glycyl endopeptidase from Carica papaya: a cysteine endopeptidase of unusual substrate specificity. |
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| Related PDB | 1gec |
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| Related Swiss-prot | P05994 |
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| [3] |
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| PubMed ID | 8862553 |
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| Journal | Protein Eng |
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| Year | 1996 |
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| Volume | 9 |
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| Pages | 525-9 |
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| Authors | Baker KC, Taylor MA, Cummings NJ, Tunon MA, Worboys KA, Connerton IF |
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| Title | Autocatalytic processing of pro-papaya proteinase IV is prevented by crowding of the active-site cleft. |
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| comments | This enzyme belongs to the peptidase family-C1.
According to the paper [1], the catalytic mechanism of this enzyme could be analogous to those in papain and other cysteine proteinases. Moreover, the Cys25/His159 ion-pair is insufficient for catalytc competence in these enzymes [1].
Considering the structural similarities to other homologous peptidases, the sidechain of Gln19 might form an oxyanion hole, together with the mainchain amide of Cys25.
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| created | updated |
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| 2002-07-01 | 2012-10-23 |
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