Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The secreted Mac protein made by serotype M1 group A Streptococcus (GAS) (designated Mac(5005)) inhibits opsonophagocytosis and killing of GAS by human polymorphonuclear neutrophils. This protein also has cysteine endopeptidase activity against human immunoglobulin G (IgG). Site-directed mutagenesis was used to identify histidine and aspartic acid residues important for Mac IgG endopeptidase activity. Replacement of His262 with Ala abolished Mac5005 IgG endopeptidase activity. Asp284Ala and Asp286Ala mutant proteins had compromised enzymatic activity, whereas 21 other Asp-to-Ala mutant proteins cleaved human IgG at the apparent wild-type level. The results suggest that His262 is an active-site residue and that Asp284 and Asp286 are important for the enzymatic activity or structure of Mac protein. These Mac mutants provide new information about structure-activity relationships in this protein and will assist study of the mechanism of inhibition of opsonophagocytosis and killing of GAS by Mac.
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PMID:Histidine and aspartic acid residues important for immunoglobulin G endopeptidase activity of the group A Streptococcus opsonophagocytosis-inhibiting Mac protein. 1270 62

We prepared six anti-idiotypic monoclonal antibodies (mAbs) against parent 41S-2 mAb whose light chain is a super catalytic antibody (41S-2-L) capable of degrading targeted HIV-1gp41 molecule. Out of the obtained six mAbs, i41-7 mAb showed the strongest affinity to the parent 41S-2 mAb. The three dimensional structure of i41-7 mAb was created by molecular modeling using the deduced amino acid sequence of the light and heavy chain of i41-7 mAb. It suggests that the light and heavy chain possess catalytic triad-like structure composed of Ser, His and Asp in their conformations. Both chains of i41-7 mAb could cleave peptide bond of some peptides such as a polypeptide, TP41-1 (TPRGPDRPEGIEEEGGERDRD), as anticipated. The cleaving reaction advanced in accordance with Michaelis-Menten equation. The catalytic efficiency (kcat/Km) of light and heavy chain was 9.1 x 10(3) and 1.7 x 10(4) M(-1) x min(-1), respectively, while the intact i41-7 mAb did not exhibit any catalytic activity. The first cleaved bond of the TP41-1 peptide by the light chain was between 14E and 15G in the sequence. It was revealed that both light and heavy chains had endopeptidase characteristics.
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PMID:Endopeptidase character of monoclonal antibody i41-7 subunits. 1270 27

Chorioangiomas are benign angiomatous tumours of the placenta occurring with a frequency of approximately one per cent of all examined placentae. Hypoxia and genetic factors are discussed to be predisposing factors for chorioangiomas. However, not much is known about the tumorigenesis of these benign tumours. Screening with various antibodies in a rare case of chorangiomatosis, we found disseminated spindle cells coexpressing vascular epithelial growth factor (VEGF), neutral endopeptidase 24.11 (NEP/CD10), and KIT protein (CD117) within the tumour stroma. A possible involvement of such factors in angiogenesis and tumorigenesis of chorioangiomas/chorangiomatosis has not been studied so far.Seven placentae with chorioangiomas (n=6) or chorangiomatosis (n=1), six normal placentae, and four cutaneous haemangiomas were analysed immunohistochemically (ABC and APAAP methods) using antibodies against VEGF, NEP, KIT protein, as well as endothelial markers like PECAM-1 (CD31), CD34, v. Willebrand factor (factor VIII), and ulex europaeus. In addition, analysis of c-kit 'gain of function' mutation Asp 816 to Val by means of Hinfl digestion and direct sequencing of semi-nested polymerase chain reaction products was performed. All chorioangiomas and haemangiomas strongly expressed the endothelial markers CD34, CD31, and FVIII, while only weak expression of ulex lectin was noted. Disseminated groups of VEGF-, NEP-, and KIT protein-positive spindle cells, which coexpressed vimentin and smooth-muscle actin were identified as myofibroblasts in the stroma of four chorioangiomas. These spindle cells were quantified as numerous in two and as rare in two other cases. No VEGF-positive myofibroblasts, however, were detected in the villous stroma of normal control placentae and haemangiomas. Only scattered perivascular myofibroblasts expressing KIT protein and NEP were detected in early gestational placenta controls. In all chorioangiomas and chorangiomatosis PCR analysis failed to unveil c-kit 'gain of function' mutation Asp 816 to Val in KIT protein-positive spindle cells. Moreover, a significant increase in mast cells was observed only in the haemangiomas. As expected, endothelial origin of chorioangiomas/chorangiomatosis was verified by CD31, CD34, FVIII expression. Myofibroblastic spindle cells expressing VEGF and NEP may be precursor cells in these peculiar angiomatous tumours. Although activating c-kit mutation Asp 816 to Val was not detected by PCR, the presence of KIT protein (CD117)-positive intratumoral myofibroblastic spindle cells in chorioangiomas and chorangiomatosis might suggest involvement of the stem cell factor (SCF)-receptor in pathologically enhanced angiogenesis.
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PMID:VEGF-, KIT protein- and neutral endopeptidase (NEP/CD10)-positive myofibroblasts-precursors of angiogenesis in chorioangiomas? 1285 66

The accumulation of D-isomers of aspartic acid (D-Asp) in proteins during aging has been implicated in the pathogenesis of Alzheimer's disease, cataracts, and arteriosclerosis. Here, we identified a specific lactacystin-sensitive endopeptidase that cleaves the D-Asp-containing protein and named it D-aspartyl endopeptidase (DAEP). DAEP has a multi-complex structure (MW: 600kDa) and is localized in the inner mitochondrial membrane of mouse and rabbit, but DAEP activity was not detected in Escherichia coli, Saccharomyces cerevisiae, and Caenorhabditis elegans. A specific inhibitor for DAEP was newly synthesized, and inhibited DAEP activity (IC(50), 3microM), a factor of 10 greater than lactacystin on DAEP. On the other hand, the inhibitor did not inhibit either the 20S or 26S proteasome.
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PMID:Mammalian D-aspartyl endopeptidase: a scavenger for noxious racemized proteins in aging. 1474 96

In the senescing endosperm of germinating castor bean (Ricinus communis) a special organelle (the ricinosome) releases a papain-type cysteine endopeptidase (CysEP) during the final stages of cellular disintegration. Protein cleavage sites for the Ricinus CysEP were determined with fluorogenic peptides (Abz-Xaa-Arg-/-Gln-Gln-Tyr(NO2)-Asp). The highest kcat/Km values were obtained with neutral amino acid residues with large aliphatic and non-polar (Leu, Val, Ile, Met) or aromatic (Phe, Tyr, Trp) side-chains. A second series (Abz-Leu-Xaa-/Gln-Pro-Tyr(NO2)-Asp) was evaluated. Based on these results, the covalent binding inhibitor H-D-Val-Leu-Lys-chloromethylketone (CMK) was chosen as substrate analogue for replacement in the catalytic site. Unusually, CysEP cleaved beta-casein N and C-terminal to the amino acid proline. CysEP was crystallized, its structure was solved by molecular replacement at 2.0 A resolution and refined to a R-factor of 18.1% (Rfree=22.6%). The polypeptide chain folds as in papain into two domains divided by the active site cleft, an elongated surface depression harboring the active site. The non-primed specificity subsites of the proteinase are clearly defined by the H-D-Val-Leu-Lys-CMK-inhibitor covalently bound to the active site. The absence of the occluding loop, which blocks the active site of exopeptidases at the C-terminal side of the scissile bond, identifies CysEP as an endopeptidase. The more open pocket of the Ricinus CysEP correlates with the extended variety of substrate amino acid residues accommodated by this enzyme, including even proline at the P1 and P1' positions. This may allow the enzyme to attack a greater variety of proteins during programmed cell death.
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PMID:The 2.0 A crystal structure and substrate specificity of the KDEL-tailed cysteine endopeptidase functioning in programmed cell death of Ricinus communis endosperm. 1503 72

Cathepsin B is a lysosomal cysteine protease exhibiting mainly dipeptidyl carboxypeptidase activity, which decreases dramatically above pH 5.5, when the enzyme starts acting as an endopeptidase. Since the common cathepsin B assays are performed at pH 6 and do not distinguish between these activities, we synthesized a series of peptide substrates specifically designed for the carboxydipeptidase activity of cathepsin B. The amino-acid sequences of the P(5)-P(1) part of these substrates were based on the binding fragments of cystatin C and cystatin SA, the natural reversible inhibitors of papain-like cysteine protease. The sequences of the P'(1)-P'(2) dipeptide fragments of the substrates were chosen on the basis of the specificity of the S'(1)-S'(2) sites of the cathepsin B catalytic cleft. The rates of hydrolysis by cathepsin B and papain, the archetypal cysteine protease, were monitored by a continuous fluorescence assay based on internal resonance energy transfer from an Edans to a Dabcyl group. The fluorescence energy donor and acceptor were attached to the C- and the N-terminal amino-acid residues, respectively. The kinetics of hydrolysis followed the Michaelis-Menten model. Out of all the examined peptides Dabcyl-R-L-V-G-F- E(Edans) turned out to be a very good substrate for both papain and cathepsin B at both pH 6 and pH 5. The replacement of Glu by Asp turned this peptide into an exclusive substrate for cathepsin B not hydrolyzed by papain. The substitution of Phe by Nal in the original substrate caused an increase of the specificity constant for cathepsin B at pH 5, and a significant decrease at pH 6. The results of kinetic studies also suggest that Arg in position P(4) is not important for the exopeptidase activity of cathepsin B, and that introducing Glu in place of Val in position P(2) causes an increase of the substrate preference towards this activity.
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PMID:Fluorogenic peptide substrates for carboxydipeptidase activity of cathepsin B. 1509 28

The extracellular matrix (ECM) of bone and dentin contains several non-collagenous proteins. One category of non-collagenous protein is termed the SIBLING (Small Integrin-Binding LIgand, N-linked Glycoprotein) family, that includes osteopontin (OPN), bone sialoprotein (BSP), dentin matrix protein 1 (DMP1), dentin sialophosphoprotein (DSPP), and matrix extracellular phosphoglycoprotein (MEPE). These polyanionic SIBLING proteins are believed to play key biological roles in the mineralization of bone and dentin. Although the specific mechanisms involved in controlling bone and dentin formation are still unknown, it is clear that some functions of the SIBLING family members are dependent on the nature and extent of post-translational modifications (PTMs), such as phosphorylation, glycosylation, and proteolytic processing, since these PTMs would have significant effects on their structure. OPN and BSP are present in the ECM of bone and dentin as full-length forms, whereas amino acid sequencing indicates that DMP1 and DSPP exist as proteolytically processed fragments that result from scission of X-Asp bonds. We hypothesized that the processing of DMP1 and DSPP is catalyzed by the PHEX enzyme, since this protein, an endopeptidase that is predominantly expressed in bone and tooth, has a strong preference for cleavage at the NH2-terminus of aspartyl residue. We envision that the proteolytic processing of DMP1 and DSPP may be an activation process that plays a significant, crucial role in osteogenesis and dentinogenesis, and that a failure in this processing would cause defective mineralization in bone and dentin, as observed in X-linked hypophosphatemic rickets.
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PMID:Post-translational modifications of sibling proteins and their roles in osteogenesis and dentinogenesis. 1518 31

LAS enzymes are a group of metallopeptidases that share an active site architecture and a core folding motif and have been named according to the group members lysostaphin, D-Ala-D-Ala carboxypeptidase and sonic hedgehog. Escherichia coli MepA is a periplasmic, penicillin-insensitive murein endopeptidase that cleaves the D-alanyl-meso-2,6-diamino-pimelyl amide bond in E. coli peptidoglycan. The enzyme lacks sequence similarity with other peptidases, and is currently classified as a peptidase of unknown fold and catalytic class in all major data bases. Here, we build on our observation that two motifs, characteristic of the newly described LAS group of metallopeptidases, are conserved in MepA-type sequences. We demonstrate that recombinant E. coli MepA is sensitive to metal chelators and that mutations in the predicted Zn2+ ligands His-113, Asp-120, and His-211 inactivate the enzyme. Moreover, we present the crystal structure of MepA. The active site of the enzyme is most similar to the active sites of lysostaphin and D-Ala-D-Ala carboxypeptidase, and the fold is most closely related to the N-domain of sonic hedgehog. We conclude that MepA-type peptidases are LAS enzymes.
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PMID:Peptidoglycan amidase MepA is a LAS metallopeptidase. 1529 90

A novel staphylolytic enzyme, ALE-1, is a glycylglycine endopeptidase produced by Staphylococcus capitis EPK1. ALE-1 possesses seven histidines. Chemical modification studies using diethylpyrocarbonate and iodoacetic acid suggested that a histidine or tyrosine residue(s) in the molecule is important for the organism's staphylolytic activity. All of the histidine residues, one tyrosine, and one aspartic acid residue in the N-terminally truncated ALE-1 (DeltaN-term ALE-1) were systematically altered by site-directed mutagenesis, and the enzyme activities and metal contents of the variants were measured. Our studies indicated that His-150, His-200, His-231, His-233, and Asp-154 are essential for the enzyme activity of DeltaN-term ALE-1. Except for His-150 and Asp-154, all of these amino acids were located within the 38-amino-acid region conserved among 11 proteins, including 5 staphylolytic endopeptidases. Inductively coupled plasma-mass spectrometric analysis of DeltaN-term ALE-1 revealed that it contains one atom of zinc per molecule. Measurement of the zinc content of the mutant DeltaN-term ALE-1 suggested that His-150 and -233 are important for zinc binding; their loss in these variant enzymes coincided with the loss of staphylolytic activity. These results strongly suggest that ALE-1 is a novel member of zinc metalloproteases.
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PMID:Mutation analysis of the histidine residues in the glycylglycine endopeptidase ALE-1. 1562 19

Metacaspases in plants, fungi, and protozoa constitute new members of a conserved superfamily of caspase-related proteases. A yeast caspase-1 protein (Yca1p), which is the single metacaspase in Saccharomyces cerevisiae, was shown to mediate apoptosis triggered by oxidative stress or aging in yeast. To examine whether plant metacaspase genes are functionally related to YCA1, we carried out analyses of AtMCP1b and AtMCP2b, representing the two subtypes of the Arabidopsis metacaspase family, utilizing yeast strains with wild-type and the disrupted YCA1 gene (yca1Delta). Inducible expression of AtMCP1b and AtMCP2b significantly promoted yeast apoptosis-like cell death of both the wild-type and yca1Delta strains, relative to the vector controls, during oxidative stress and early aging process. Mutational analysis of the two AtMCPs revealed that their cell-death-inducing activities depend on their catalytic center cysteine residues as well as caspase-like processing. In addition, the phenotype induced by the expression of two AtMCPs was effectively prevented when the cells were pretreated with a broad-spectrum caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl-ketone. These results suggest that the two subtypes of Arabidopsis metacaspases are functionally related to Yca1p with caspase-like characteristics. However, we found that bacterial and yeast extracts containing AtMCP1b, AtMCP2b, or Yca1p exhibit arginine/lysine-specific endopeptidase activities but cannot cleave caspase-specific substrates. Together, the results strongly implicate that expression of metacaspases could result in the activation of downstream protease(s) with caspase-like activities that are required to mediate cell death activation via oxidative stress in yeast. Metacaspases from higher plants may serve similar functions.
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PMID:Two Arabidopsis metacaspases AtMCP1b and AtMCP2b are arginine/lysine-specific cysteine proteases and activate apoptosis-like cell death in yeast. 1569 45


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