scholarly journals The design of peptidyldiazomethane inhibitors to distinguish between the cysteine proteinases calpain II, cathepsin L and cathepsin B

1988 ◽  
Vol 253 (3) ◽  
pp. 751-758 ◽  
Author(s):  
C Crawford ◽  
R W Mason ◽  
P Wikstrom ◽  
E Shaw
Keyword(s):  
Cathepsin B ◽  
Cathepsin L ◽  
Cysteine Proteinases ◽  
Inhibitory Effects ◽  
Enzyme Functions ◽  
Calpain Ii

A series of peptidyldiazomethanes was synthesized and tested as inactivators of the cysteine proteinases calpain II, cathepsin L and cathepsin B. Inactivators that react rapidly and that show a degree of selectivity between the enzymes were identified. Z-Tyr(I)-Ala-CHN2 (where Z represents benzyloxycarbonyl) reacts rapidly with cathepsin L and more slowly with cathepsin B, but does not inhibit calpain II. Z-Leu-Leu-Tyr-CHN2 reacts rapidly with cathepsin L and calpain II but very slowly with cathepsin B. Boc-Val-Lys(epsilon-Z)Leu-Tyr-CHN2 (where Boc represents t-butyloxycarbonyl) reacts more rapidly with calpain II than with cathepsin L or cathepsin B. The discriminating inhibitory effects of these compounds make them potentially useful for investigation of enzyme functions in vivo. The data presented also provide insights into the subsite specificity of calpain.

The cysteine proteinases of Schistosoma mansoni cercariae

Parasitology ◽  
1997 ◽  
Vol 114 (2) ◽  
pp. 105-112 ◽  
Author(s):  
J. P. DALTON ◽  
K. A. CLOUGH ◽  
M. K. JONES ◽  
P. J. BRINDLEY
Keyword(s):  
Schistosoma Mansoni ◽  
Cathepsin B ◽  
Cathepsin L ◽  
Serine Proteinase ◽  
Skin Penetration ◽  
Scanning Electron Micrographs ◽  
Cysteine Proteinases ◽  
Similar Function ◽  
Substrate Preferences ◽  
Serine Proteinase Activity

Based on substrate preferences, cercariae of Schistosoma mansoni were seen to express both cathepsin L and cathepsin B cysteine proteinases, although the former activity was many -fold greater. Two cathepsin L activities identified in cercarial extracts by zymography co-migrated with activities in extracts of 3 h and 24 h schisotosomula and in extracts of adult worms. Since these enzymes have been implicated in haemoglob in digestion by adult worms, they may perform a similar function in schistosomula. Immunolocalization using scanning electron micrographs showed that cathepsin L and cathepsin B proteinases were present in the cercarial post-acetabular glands. In addition, cercarial serine proteinase activities considered to facilitate skin penetration efficiently cleaved the substrates Z-Gly-Pro-Arg-NHMec and Z-Gly-Pro-Lys-NHMec. Cercariae release most of this serine proteinase activity when induced to secrete the contents of their acetabular glands. In contrast, newly transformed 3 h and 24 h schistosomula did not express this activity.

scholarly journals Effects of microbial proteinase inhibitors on the degradation of endogenous and internalized proteins by rat yolk sacs

1981 ◽  
Vol 196 (1) ◽  
pp. 41-48 ◽  
Author(s):  
S E Knowles ◽  
F J Ballard ◽  
G Livesey ◽  
K E Williams
Keyword(s):  
Bovine Serum Albumin ◽  
Cathepsin B ◽  
Proteinase Inhibitors ◽  
Cathepsin L ◽  
Minor Role ◽  
Protein Breakdown ◽  
Inhibitory Effects ◽  
Endogenous Protein ◽  
A Minor

1. The effects of leupeptin and other microbial proteinase inhibitors were measured in rat yolk sacs on the uptake and degradation of formaldehyde-denatured 125I-labelled bovine serum albumin as well as on the degradation of 3H-labelled endogenous protein. 2. Leupeptin, at concentrations between 1 and 100 micrograms/ml, inhibits the degradation of added albumin without affecting pinocytic uptake. Accordingly large amounts of undegraded albumin accumulate within the tissue. 3. Removal of leupeptin produces a rapid recovery of the capacity to degrade albumin. 4. Endogenous protein degradation is rapidly inhibited by leupeptin, but to a far lesser extent than the breakdown of albumin. However, the inhibition is only slightly reversed on removal of leupeptin. 5. Degradation of both albumin and endogenous protein in intact yolk sacs is inhibited by the microbial proteinase inhibitors in the order: leupeptin greater than antipain greater than chymostatin; elastatinal, pepstatin and bestatin are ineffective. 6. Similar results are found when albumin is incubated in yolk-sac homogenates at pH 4 with the inhibitors. 7. The marked inhibitory effects of leupeptin, antipain and chymostatin suggest that cathepsin B and possibly cathepsin L participate in the degradation of 125I-labelled albumin in yolk sacs. By comparison, the smaller inhibitory effects of the proteinase inhibitors on endogenous protein breakdown imply a minor role of lysosomal cathepsins in this process.

scholarly journals The identification of active forms of cysteine proteinases in Kirsten-virus-transformed mouse fibroblasts by use of a specific radiolabelled inhibitor

1989 ◽  
Vol 257 (1) ◽  
pp. 125-129 ◽  
Author(s):  
R W Mason ◽  
D Wilcox ◽  
P Wikstrom ◽  
E N Shaw
Keyword(s):  
Cathepsin B ◽  
Cathepsin L ◽  
Active Form ◽  
Culture Conditions ◽  
Secreted Protein ◽  
Cysteine Proteinases ◽  
Tumour Invasion ◽  
Specific Antibodies ◽  
Mouse Fibroblasts

The major active forms of cathepsins B and L were identified in Kirsten-virus-transformed mouse fibroblasts by the use of a specific radiolabelled inhibitor, benzyloxycarbonyl-Tyr(-125I)-Ala-CHN2. No other proteins were labelled, demonstrating the specificity of this inhibitor for cysteine proteinases. Cathepsins B and L were distinguished by the use of specific antibodies. One active form of cathepsin B, Mr 33,000-35,000, and two active forms of cathepsin L, Mr 30,000 and 23,000, were identified. The intracellular precursors of these proteins had higher Mr values of 39,000 and 36,000 for cathepsins B and L respectively, as shown by pulse-chase experiments with [35S]methionine-labelled proteins. These did not react with the inhibitor under our culture conditions. The precursor of cathepsin L was secreted whereas the precursor of cathepsin B was not, demonstrating that secretions of the two enzymes are regulated differently. In contrast with results found previously for the purified protein [Mason, Gal & Gottesman (1987) Biochem. J. 248, 449-454], the secreted precursor form of cathepsin L did not react with the inhibitor either, indicating that it is not active and therefore, as such, cannot be directly involved in tumour invasion. The secreted protein did react with the inhibitor when incubated at pH 3.0, showing that the protein can be activated, although this did not occur under our culture conditions.

scholarly journals Quantification of cathepsins B and L in cells

1998 ◽  
Vol 332 (2) ◽  
pp. 499-505 ◽  
Author(s):  
Ruye XING ◽  
Adele K. ADDINGTON ◽  
Robert W. MASON
Keyword(s):  
Active Site ◽  
Total Protein ◽  
Cathepsin B ◽  
Mammalian Cells ◽  
Cultured Cells ◽  
Cathepsin L ◽  
Breast Tumour ◽  
Cathepsin S ◽  
Cysteine Proteinases ◽  
Breast Tumour Cells

A method for quantifying active cysteine proteinases in mammalian cells has been developed using an active-site-directed inhibitor. Fluoren-9-ylmethoxycarbonyl(di-iodotyrosylalanyl)-diazomethane (Fmoc-[I2]Tyr-Ala-CHN2) was prepared and shown to react irreversibly with cathepsins B and L, but not with cathepsin S. The non- and mono-iodo forms of the inhibitor reacted with all three enzymes. These results demonstrate that, unlike cathepsins B and L, cathepsin S has a restricted S2-binding site that cannot accommodate the bulky di-iodotyrosine. Fmoc-[I2]Tyr-Ala-CHN2 was able to penetrate cells and react with active enzymes within the cells. A radiolabelled form of the inhibitor was synthesized and the concentration of functional inhibitor was established by titration with papain. This inhibitor was used to quantify active cysteine proteinases in cultured cells. Active cathepsin B was found to be expressed by all of the cells studied, consistently with a housekeeping role for this enzyme. Active forms of cathepsin L were also expressed by all of the cells, but in different quantities. Two additional proteins were labelled in some of the cells, and these may represent other non-characterized proteinases. Higher levels of active cathepsins B and L, and an unidentified protein of Mr 39000, were found in breast tumour cells that are invasive, compared with those that are not invasive. From the data obtained, it can be calculated that the concentrations of both active cathepsins B and L in lysosomes can be as high as 1 mM, each constituting up to 20% of total protein in the organelle. This new technique provides a more direct procedure for determining the proteolytic potential of cellular lysosomes.

scholarly journals Human kidney cathepsins B and L. Characterization and potential role in degradation of glomerular basement membrane

1988 ◽  
Vol 252 (1) ◽  
pp. 301-304 ◽  
Author(s):  
W H Baricos ◽  
Y Zhou ◽  
R W Mason ◽  
A J Barrett
Keyword(s):  
Basement Membrane ◽  
Glomerular Basement Membrane ◽  
Cathepsin B ◽  
Cathepsin L ◽  
Polyacrylamide Gel Electrophoresis ◽  
Human Kidney ◽  
Ph Optimum ◽  
Dose Dependent ◽  
Hydrolysis Of

Cathepsins B and L were purified from human kidney. SDS/polyacrylamide-gel electrophoresis demonstrated that cathepsins B and L, Mr 27000-30000, consist of disulphide-linked dimers, subunit Mr values 22000-25000 and 5000-7000. The pH optimum for the hydrolysis of methylcoumarylamide (-NHMec) substrates (see below) is approx. 6.0 for each enzyme. Km and kcat. are 252 microM and 364s-1 and 2.2 microM and 25.8 s-1 for the hydrolysis of Z-Phe-Arg-NHMec (where Z- represents benzyloxycarbonyl-) by cathepsins B and L respectively, and 184 microM and 158 s-1 for the hydrolysis of Z-Arg-Arg-NHMec by cathepsin B. A 10 min preincubation of cathepsin B (40 degrees C) or cathepsin L (30 degrees C) with E-64 (2.5 microM) results in complete inhibition. Under identical conditions Z-Phe-Phe-CHN2 (0.56 microM) completely inhibits cathepsin L but has little effect on cathepsin B. Incubation of glomerular basement membrane (GBM) with purified human kidney cathepsin L resulted in dose-dependent (10-40 nM) GBM degradation. In contrast, little degradation of GBM (less than 4.0%) was observed with cathepsin B. The pH optimum for GBM degradation by cathepsin L was 3.5. Cathepsin L was significantly more active in degrading GBM than was pancreatic elastase, trypsin or bacterial collagenase. These data suggest that cathepsin L may participate in the lysosomal degradation of GBM associated with normal GBM turnover in vivo.

scholarly journals A comparison of four cathepsins (B, L, N and S) with collagenolytic activity from rabbit spleen

1988 ◽  
Vol 256 (2) ◽  
pp. 433-440 ◽  
Author(s):  
R A Maciewicz ◽  
D J Etherington
Keyword(s):  
Cathepsin B ◽  
Specific Activity ◽  
Cathepsin L ◽  
Cross Reactivity ◽  
Enzymic Activity ◽  
Enzyme Linked Immunosorbent Assay ◽  
Collagenolytic Activity ◽  
Cysteine Proteinases ◽  
Isoelectric Points ◽  
Multiple Charge

We have separated four cathepsins (B, L, N and S) from rabbit spleen. They are all collagen-degrading cysteine proteinases, with Mr values of 25,250, 23,500, 34,000 and 30,000 for cathepsin B, L, N and S respectively. Cathepsins B, N and S have isoelectric points of 5.4, 6.2 and 6.8 respectively, whereas cathepsin L exhibited multiple charge forms in the range 5.0-5.7. A comparison of their specific activity against a variety of protein and synthetic substrates shows many differences. These differences can be visually illustrated through isoelectric focusing and detection of enzymic activity with protein and synthetic-substrate overlays. By using an enzyme-linked immunosorbent assay based on the binding to chicken cystatin and detection with polyclonal and monoclonal antibodies to native cathepsins B and L, no cross-reactivity of the four native enzymes was observed. Studies on the co-operative or synergistic effect in degrading collagen indicated that, of the different combinations tested, only the combination of cathepsin B and N exhibited enhanced collagenolysis.

scholarly journals Porcine deltacoronavirus enters cells via two pathways: A protease-mediated one at the cell surface and another facilitated by cathepsins in the endosome

2019 ◽  
Vol 294 (25) ◽  
pp. 9830-9843 ◽  
Author(s):  
Jialin Zhang ◽  
Jianfei Chen ◽  
Da Shi ◽  
Hongyan Shi ◽  
Xin Zhang ◽  
...  
Keyword(s):  
Cell Surface ◽  
Cell Cultures ◽  
Viral Entry ◽  
Cathepsin B ◽  
Cathepsin L ◽  
The United States ◽  
Protein Cleavage ◽  
S Protein ◽  
Endosomal Pathway

Porcine deltacoronavirus (PDCoV) is a pathogen belonging to the genus Deltacoronavirus that in 2014 caused outbreaks of piglet diarrhea in the United States. To identify suitable therapeutic targets, a more comprehensive understanding of the viral entry pathway is required, particularly of the role of proteases. Here, we identified the proteases that activate the viral spike (S) glycoprotein to initiate cell entry and also pinpointed the host-cellular pathways that PDCoV uses for entry. Our results revealed that cathepsin L (CTSL) and cathepsin B (CTSB) in lysosomes and extracellular trypsin in cell cultures independently activate the S protein for membrane fusion. Pretreating the cells with the lysosomal acidification inhibitor bafilomycin-A1 (Baf-A1) completely inhibited PDCoV entry, and siRNA-mediated ablation of CTSL or CTSB expression significantly reduced viral infection, indicating that PDCoV uses an endosomal pathway for entry. Of note, trypsin treatment of cell cultures also activated PDCoV entry, even when the endosomal pathway was inhibited. This observation indicated that trypsin-induced S protein cleavage and activation in cell cultures enables viral entry directly from the cell surface. Our results provide critical insights into the PDCoV infection mechanism, uncovering two distinct viral entry pathways: one through cathepsin L and cathepsin B in the endosome and another via a protease at the cell surface. Because PDCoV infection sites represent a proteases-rich environment, these findings suggest that endosome inhibitor treatment alone is insufficient to block PDCoV entry into intestinal epithelial cells in vivo. Therefore, approaches that inhibit viral entry from the cell membrane should also be considered.

scholarly journals Cathepsin Cs Are Key for the Intracellular Survival of the Protozoan Parasite, Toxoplasma gondii

2006 ◽  
Vol 282 (7) ◽  
pp. 4994-5003 ◽  
Author(s):  
Xuchu Que ◽  
Juan C. Engel ◽  
David Ferguson ◽  
Annette Wunderlich ◽  
Stanislas Tomavo ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Cathepsin B ◽  
Parasitophorous Vacuole ◽  
Cathepsin L ◽  
Protozoan Parasite ◽  
Cysteine Proteases ◽  
Intracellular Survival ◽  
Chemotherapeutic Agents ◽  
Cathepsin C

Cysteine proteases play key roles in apicomplexan invasion, organellar biogenesis, and intracellular survival. We have now characterized five genes encoding papain family cathepsins from Toxoplasma gondii, including three cathepsin Cs, one cathepsin B, and one cathepsin L. Unlike endopeptidases cathepsin B and L, T. gondii cathepsin Cs are exopeptidases and remove dipeptides from unblocked N-terminal substrates of proteins or peptides. TgCPC1 was the most highly expressed cathepsin mRNA in tachyzoites (by real-time PCR), but three cathepsins, TgCPC1, TgCPC2, and TgCPB, were undetectable in in vivo bradyzoites. The specific cathepsin C inhibitor, Gly-Phe-dimethylketone, selectively inhibited the TgCPCs activity, reducing parasite intracellular growth and proliferation. The targeted disruption of TgCPC1 does not affect the invasion and growth of tachyzoites as TgCPC2 is then up-regulated and may substitute for TgCPC1. TgCPC1 and TgCPC2 localize to constitutive secretory vesicles of tachyzoites, the dense granules. T. gondii cathepsin Cs are required for peptide degradation in the parasitophorous vacuole as the degradation of the marker protein, Escherichia coli β-lactamase, secreted into the parasitophorous vacuole of transgenic tachyzoites was completely inhibited by the cathepsin C inhibitor. Cathepsin C inhibitors also limited the in vivo infection of T. gondii in the chick embryo model of toxoplasmosis. Thus, cathepsin Cs are critical to T. gondii growth and differentiation, and their unique specificities could be exploited to develop novel chemotherapeutic agents.

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