Recombinant human cathepsin X is a carboxymonopeptidase only: a comparison with cathepsins B and L.
The S1 and S2 subsite specificity of recombinant human cathepsins X was studied using fluorescence resonance energy transfer (FRET) peptides with the general sequences Abz-Phe-Xaa-Lys(Dnp)-OH and Abz-Xaa-Arg-Lys(Dnp)-OH, respectively (Abz=ortho-aminobenzoic acid and Dnp=2,4-dinitrophenyl; Xaa=various amino acids). Cathepsin X cleaved all substrates exclusively as a carboxymonopeptidase and exhibited broad specificity. For comparison, these peptides were also assayed with cathepsins B and L. Cathepsin L hydrolyzed the majority of them with similar or higher catalytic efficiency than cathepsin X, acting as an endopeptidase mimicking a carboxymonopeptidase (pseudo-carboxymonopeptidase). In contrast, cathepsin B exhibited poor catalytic efficiency with these substrates, acting as a carboxydipeptidase or an endopeptidase. The S1' subsite of cathepsin X was mapped with the peptide series Abz-Phe-Arg-Xaa-OH and the enzyme preferentially hydrolyzed substrates with hydrophobic residues in the P1' position.
Puzer
Luciano
L
Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de São Paulo, Rua Três de Maio 100, 04044-020 São Paulo, Brazil.
Cotrin
Simone S
SS
Cezari
Maria H S
MH
Hirata
Izaura Y
IY
Juliano
Maria A
MA
Stefe
Ivica
I
Turk
Dusan
D
Turk
Boris
B
Juliano
Luiz
L
Carmona
Adriana K
AK
D002268:Carboxypeptidases / Q000737:chemistry* / Q000235:genetics; D002401:Cathepsin B / Q000737:chemistry* / Q000235:genetics; D056657:Cathepsin K; D056668:Cathepsin L; D002403:Cathepsins / Q000737:chemistry* / Q000235:genetics; D003546:Cysteine Endopeptidases / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D010455:Peptides / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013379:Substrate Specificity / Q000235:genetics / Q000502:physiology
D010455:Peptides; D011994:Recombinant Proteins; D002268:Carboxypeptidases; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; C534281:CTSL protein, human; D056668:Cathepsin L; C534130:CTSK protein, human; D056657:Cathepsin K