scholarly journals L-trans-Epoxysuccinyl-leucylamido(4-guanidino)butane (E-64) and its analogues as inhibitors of cysteine proteinases including cathepsins B, H and L

1982 ◽  
Vol 201 (1) ◽  
pp. 189-198 ◽  
Author(s):  
A J Barrett ◽  
A A Kembhavi ◽  
M A Brown ◽  
H Kirschke ◽  
C G Knight ◽  
...  

1. L-trans-Epoxysuccinyl-leucylamido(4-guanidino)butane (E-64) at a concentration of 0.5 mM had no effect on the serine proteinases plasma kallikrein and leucocyte elastase or the metalloproteinases thermolysin and clostridial collagenase. In contrast, 10 muM-E-64 rapidly inactivated the cysteine proteinases cathepsins B, H and L and papain (t0.5 = 0.1-17.3s). The streptococcal cysteine proteinase reacted much more slowly, and there was no irreversible inactivation of clostripain. The cysteine-dependent exopeptidase dipeptidyl peptidase I was very slowly inactivated by E-64. 2. the active-site-directed nature of the interaction of cathepsin B and papain with E-64 was established by protection of the enzyme in the presence of the reversible competitive inhibitor leupeptin and by the stereospecificity for inhibition by the L as opposed to the D compound. 3. It was shown that the rapid stoichiometric reaction of the cysteine proteinases related to papain can be used to determine the operational molarity of solutions of the enzymes and thus to calibrate rate assays. 4. The apparent second-order rate constants for the inactivation of human cathepsins B and H and rat cathepsin L by a series of structural analogues of E-64 are reported, and compared with those for some other active-site-directed inhibitors of cysteine proteinases. 5. L-trans-Epoxysuccinyl-leucylamido(3-methyl)butane (Ep-475) was found to inhibit cathepsins B and L more rapidly than E-64. 6. Fumaryl-leucylamido(3-methyl)butane (Dc-11) was 100-fold less reactive than the corresponding epoxide, but was nevertheless about as effective as iodoacetate.

1998 ◽  
Vol 332 (2) ◽  
pp. 499-505 ◽  
Author(s):  
Ruye XING ◽  
Adele K. ADDINGTON ◽  
Robert W. MASON

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.


1996 ◽  
Vol 318 (2) ◽  
pp. 395-399 ◽  
Author(s):  
Gilles LALMANACH ◽  
Roger MAYER ◽  
Carole SERVEAU ◽  
Julio SCHARFSTEIN ◽  
Francis GAUTHIER

Biotin-labelled peptidyl diazomethane inhibitors of cysteine proteinases, based on the N-terminal substrate-like segment of human cystatin C, a natural inhibitor of cysteine proteinases, were synthesized. These synthetic derivatives were tested as irreversible inhibitors of cruzipain, the major cysteine proteinase of Trypanosoma cruzi, to compare the kinetics of the inhibition of the parasite proteinase with that of the mammalian cathepsins B and L. The accessibility of the active sites of these proteinases to these probes was also investigated. The inhibition of cruzipain by Biot-LVG-CHN2 (where Biot represents biotinyl and L,V and G are single-letter amino acid residue abbreviations) and Biot-Ahx-LVG-CHN2 (where Ahx represents 6-aminohexanoic acid) was similar to that of unlabelled inhibitor. Biotin labelling of the inhibitor slowed the inhibition of both cathepsin B and cathepsin L. Adding a spacer arm (Ahx) between the biotin and the peptide moiety of the derivative increased the inhibition of cathepsin B but not that of cathepsin L. The discrimination provided by this spacer is probably due to differences in the topologies of the binding sites of proteinases, a feature that can be exploited to improve targeting of individual cysteine proteinases. Analysis of the blotted proteinases revealed marked differences in the accessibility of extravidin–peroxidase conjugate to the proteinase-bound biotinylated inhibitor. Cruzipain molecules exposed to Biot-LVG-CHN2 or Biot-Ahx-LVG-CHN2 were readily identified, but the reaction was much stronger when the enzyme was treated with the spacer-containing inhibitor. In contrast with the parasite enzyme, rat cathepsin B and cathepsin L treated with either Biot-LVG-CHN2 or Biot-Ahx-LVG-CHN2 produced no detectable bands. Papain, the archetype of this family of proteinases, was poorly labelled with Biot-LVG-CHN2, but strong staining was obtained with Biot-Ahx-LVG-CHN2. These findings suggest that optimized biotinylated diazomethanes might considerably improve their selectivity for the T. cruzi target enzyme.


2000 ◽  
Vol 347 (1) ◽  
pp. 123-129 ◽  
Author(s):  
Fernada C. Vieira PORTARO ◽  
Ana Beatriz F. SANTOS ◽  
Maria Helena S. CEZARI ◽  
Maria Aparecida JULIANO ◽  
Luiz JULIANO ◽  
...  

We have determined the kinetic parameters for the hydrolysis by papain, cathepsin B and cathepsin L of internally quenched fluorescent peptides derived from the lead peptides Abz-AAFRSAQ-EDDnp [in which Abz and EDDnp stand for o-aminobenzoic acid and N-(2,4-dinitrophenyl)ethylenediamine respectively], to map the specificity of S4 and S3 subsites, and Abz-AFRSAAQ-EDDnp, to identify the specificity of S2ʹ and S3ʹ. Abz and EDDnp were the fluorescent quencher pair. These two series of peptides were cleaved at the Arg-Ser bond and systematic modifications at P4, P3, P2ʹ and P3ʹ were made. The S4 to S2ʹ subsites had a significant influence on the hydrolytic efficiencies of the three enzymes. Only papain activity was observed to be dependent on S3ʹ, indicating that its binding site is larger than those of cathepsins B and L. Hydrophobic amino acids were accepted at S4, S3, S2ʹ and S3ʹ of the three enzymes. The best substrates for cathepsins L and B had Trp and Asn at P2ʹ respectively; variations at this position were less accepted by these enzymes. The best substrates for papain were peptides containing Trp, Tyr or Asn at P3ʹ. Basic residues at P3 and P4 were well accepted by cathepsin L and papain. We also explored the susceptibility of substrates Abz-AFRSXAQ-EDDnp, modified at P2ʹ (X), to human cathepsin B mutants from which one or two occluding loop contacts had been removed. The modifications at His111 (H111A) and His110 (H110A) of cathepsin B led to an increase in kcat values of one or two orders of magnitude. The hydrolytic efficiencies of these cathepsin B mutants became closer to those of papain or cathepsin L.


2002 ◽  
Vol 383 (5) ◽  
pp. 839-842 ◽  
Author(s):  
Natasa Sever ◽  
Metka Filipic ◽  
Joze Brzin ◽  
Tamara T. Lah

Abstract Various types of proteinases are implicated in the malignant progression of human and animal tumors. Proteinase inhibitors may therefore be useful as therapeutic agents in antiinvasive and antimetastatic treatment. The aims of this study were (1) to estimate the relative importance of proteinases in B16 cell invasion in vitro using synthetic, classspecific proteinase inhibitors and (2) to assess the inhibitory effect of some naturally occurring cysteine proteinase inhibitors. Serine proteinase inhibitor reduced invasiveness by up to 24%, whereas inhibition of aspartic proteinases reduced invasion by 11%. Synthetic inhibitors of cysteine proteinases markedly impaired invasion: cathepsin B inhibitors, particularly Ca 074Me, inhibited invasion from 20 40%, whereas cathepsin L inhibitor Clik 148 reduced invasion by 11%. The potato cysteine proteinase inhibitor PCPI 8.7 inhibited invasion by 21%, whereas another potato inhibitor, PCPI 6.6, and the mushroom cysteine proteinase inhibitor clitocypin had no effects. As the inhibitors that inhibited cathepsin B were in general more efficient at impairing the invasiveness, we conclude that of the two cysteine proteinases, cathepsin B plays a more important role than cathepsin L in murine melanoma cell invasion.


1998 ◽  
Vol 335 (3) ◽  
pp. 701-709 ◽  
Author(s):  
Ingemar BJÖRK ◽  
Kerstin NORDLING ◽  
Elke RAUB-SEGALL ◽  
Ulf HELLMAN ◽  
Steven T. OLSON

Cross-class inhibition of cysteine proteinases by serpins differs from serpin inhibition of serine proteinases primarily in that no stable serpin–cysteine proteinase complex can be demonstrated. This difference in reaction mechanism was elucidated by studies of the inactivation of the cysteine proteinases, papain and cathepsin L, by the serpin antithrombin. The two proteinases were inactivated with second-order rate constants of (1.6±0.1)×103 and (8.6±0.4)×102 M-1·s-1 respectively. An antithrombin to papain inactivation stoichiometry of ∼ 3 indicated extensive cleavage of the inhibitor concurrent with enzyme inactivation, a behaviour verified by SDS/PAGE. N-terminal sequence analyses showed cleavage predominantly at the P2–P1 bond, but also at the P2´–P3´ bond of antithrombin. The papain band in SDS/PAGE progressively disappeared on reaction of the enzyme with increasing amounts of antithrombin, but no band representing a stable antithrombin–papain complex appeared. SDS/PAGE with 125I-labelled papain showed that the disappearance of papain was caused by cleavage of the enzyme into small fragments. These results suggest a mechanism in which papain attacks a peptide bond in the reactive-bond loop of antithrombin adjacent to that involved in serine proteinase inhibition. The reaction proceeds, similarly to that between serpins and serine proteinases, to form an inactive acyl-intermediate complex, although with the substrate pathway dominating in the papain reaction. In this complex, papain is highly susceptible to proteolysis and is degraded by still active papain, which greatly decreases the lifetime of the complex and results in liberation of fragmented, inactive enzyme. This model may have relevance also for the inactivation of physiologically or pathologically important cysteine proteinases by serpins.


1986 ◽  
Vol 239 (3) ◽  
pp. 633-640 ◽  
Author(s):  
P Rauber ◽  
H Angliker ◽  
B Walker ◽  
E Shaw

A synthesis of peptidylfluoromethanes is described that utilizes the conversion of phthaloyl amino acids into their fluoromethane derivatives. These can be deblocked and elongated. The inactivation of chymotrypsin by Cbz-Phe-CH2F (benzyloxycarbonylphenylalanylfluoromethane) was found to be considerably slower than that of the analogous chloromethane. The fluoromethane analogue inactivates chymotrypsin with an overall rate constant that is 2% of that observed for the inactivation of the enzyme with the chloromethane. However, the result is the same. The reagent complexes in a substrate-like manner, with Ki = 1.4 × 10(-4) M, and alkylates the active-centre histidine residue. Cbz-Phe-Phe-CH2F and Cbz-Phe-Ala-CH2F were investigated as inactivators of the cysteine proteinase cathepsin B. The difference in reactivity between fluoromethyl ketones and chloromethyl ketones is less pronounced in the case of the cysteine proteinase than for the serine proteinase. Covalent bond formation takes place in this case also, as demonstrated by the use of a radiolabelled reagent.


Parasitology ◽  
1997 ◽  
Vol 114 (2) ◽  
pp. 105-112 ◽  
Author(s):  
J. P. DALTON ◽  
K. A. CLOUGH ◽  
M. K. JONES ◽  
P. J. BRINDLEY

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.


2018 ◽  
Vol 399 (10) ◽  
pp. 1223-1235 ◽  
Author(s):  
Andreas Porodko ◽  
Ana Cirnski ◽  
Drazen Petrov ◽  
Teresa Raab ◽  
Melanie Paireder ◽  
...  

Abstract The genome of the model plant Arabidopsis thaliana encodes three paralogues of the papain-like cysteine proteinase cathepsin B (AtCathB1, AtCathB2 and AtCathB3), whose individual functions are still largely unknown. Here we show that a mutated splice site causes severe truncations of the AtCathB1 polypeptide, rendering it catalytically incompetent. By contrast, AtCathB2 and AtCathB3 are effective proteases which display comparable hydrolytic properties and share most of their substrate specificities. Site-directed mutagenesis experiments demonstrated that a single amino acid substitution (Gly336→Glu) is sufficient to confer AtCathB2 with the capacity to tolerate arginine in its specificity-determining S2 subsite, which is otherwise a hallmark of AtCathB3-mediated cleavages. A degradomics approach utilizing proteome-derived peptide libraries revealed that both enzymes are capable of acting as endopeptidases and exopeptidases, releasing dipeptides from the C-termini of substrates. Mutation of the carboxydipeptidase determinant His207 also affected the activity of AtCathB2 towards non-exopeptidase substrates, highlighting mechanistic differences between plant and human cathepsin B. This was also noted in molecular modeling studies which indicate that the occluding loop defining the dual enzymatic character of cathepsin B does not obstruct the active-site cleft of AtCathB2 to the same extent as in its mammalian orthologues.


1989 ◽  
Vol 257 (1) ◽  
pp. 125-129 ◽  
Author(s):  
R W Mason ◽  
D Wilcox ◽  
P Wikstrom ◽  
E N Shaw

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.


1988 ◽  
Vol 254 (3) ◽  
pp. 693-699 ◽  
Author(s):  
D J Buttle ◽  
B C Bonner ◽  
D Burnett ◽  
A J Barrett

A cysteine proteinase from purulent sputum was partially purified by a method involving affinity chromatography on Sepharose-aminohexanoylphenylalanylglycinaldehyde semicarbazone. It was immunologically related to lysosomal cathepsin B from human liver and was similar in many, but not all, other aspects. It was catalytically active, as demonstrated by active-site-directed radioiodination, and hydrolysed three cathepsin B substrates, two with Km values similar to those of lysosomal cathepsin B. In addition, the rates of inactivation of the sputum and lysosomal forms of the enzyme by L-3-carboxy-2,3-transepoxypropionyl-leucylamido(4-guanidino) butane (Compound E-64) were very similar. However, the sputum enzyme differed from lysosomal cathepsin B in the following respects. Inhibition by chicken cystatin was much weaker for sputum cathepsin B than for the lysosomal enzyme. Sputum cathepsin B had greater stability at pH 7.5 and a higher apparent Mr, even after deglycosylation, than lysosomal cathepsin B. We conclude that the form of cathepsin B found in sputum is probably a truncated form of human procathepsin B, with some differences in properties that could be of physiological importance.


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