Affinity purification and properties of cathepsin-E-like acid proteinase from rat spleen.

A unique acid proteinase different from cathepsin D was purified from rat spleen by a method involving precipitation at pH 3.5, affinity chromatography on pepstatin-Sepharose 4B and concanavalin A-Sepharose 4B, chromatography on Sephadex G-100 and DEAE-Sephacel, and isoelectric focusing. A purification of 4200-fold over the homogenate was achieved and the yield was 11%. The purified enzyme appeared to be homogeneous on electrophoresis in polyacrylamide gels. The isoelectric point of the enzyme was determined to be 4.1-4.4. The enzyme hydrolyzed hemoglobin with a pH optimum of about 3.1. The molecular weight of the enzyme was estimated to be about 90000 by gel filtration on Sephadex G-100. In sodium dodecylsulfate polyacrylamide gel electrophoresis, the purified enzyme showed a single protein band corresponding to a molecular weight of about 45000. The hydrolysis of bovine hemoglobin by the enzyme was much higher than that of serum albumin. Various synthetic and natural inhibitors of the enzyme were tested. The enzyme was inhbited by Zn2+, Fe3+, Pb2+, cyanide, p-chloromercuribenzoate, iodoacetic acid and pepstatin, whereas 2-mercaptoethanol, phenylmethyl-sulfonyl fluoride and leupeptin showed no effect.     

Isolation, and catalytic and immunochemical properties of cathepsin D-like acid proteinase from rat erythrocytes

An erythrocyte membrane-associated cathepsin D-like acid proteinase, termed "EMAP," was purified to homogeneity from freshly collected rat blood in a yield of 60-65%. The molecular weight of the enzyme was determined to be 80,000-82,000 by Sephadex G-100 gel filtration. The enzyme was inhibited strongly by pepstatin and partially by HgCl2, Pb(NO3)2, and iodoacetic acid. The preferred substrate for the enzyme was hemoglobin. The enzyme also hydrolyzed serum albumin and casein, but to lesser extents, with an optimum pH of 3.5-4.0. However, it could not hydrolyze leucyl-2-naphthylamide, benzyloxycarbonyl-Phe-Arg-4-methyl-7-coumarylamide or other synthetic substrates at pH values ranging from 3.5 to 9.5. The enzyme was very similar to human EMAP in a number of enzymatic properties, whereas it differed from rat cathepsin D in several respects, such as pH stability, molecular weight, isoelectric point, and chromatographic properties. Immunologically, the enzyme cross-reacted with the rabbit antibody prepared against human EMAP. The patterns of immunoelectrophoresis, immunoblotting, and immunoprecipitation of the enzyme were remarkably similar, if not identical, to those of human EMAP. In contrast, rat EMAP showed no reaction with the rabbit antibody raised to rat spleen cathepsin D. These results indicate that EMAP is a unique cathepsin D-like acid proteinase different from ordinary cathepsin D.     

Separation of cathepsin D-like proteinase and acid thiol proteinase of squid mantle muscle

When the proteinases of the squid mantle muscle were extracted in the presence of dithiothreitol (DTT), the acid proteinase activity increased, indicating that the squid mantle muscle contains a considerable amount of the acid thiol proteinase. The crude extract hydrolyzed neither alpha-N-benzoyl-D,L-arginine-p-nitroanilide (BAPA) nor azocasein, thus refuting the presence of cathepsins B and L in the mantle muscle. The cathepsin D-like proteinase and the acid thiol proteinase were separated by Sephadex A-50 column chromatography. Each of the above partially purified proteinases was able to degrade carp actomyosin at pH 2.5 and 5.0, respectively.     

Purification and properties of cathepsin D from porcine spleen.

Cathepsin D was purified from porcine spleen to near homogeneity as determined by gel electrophoresis. The isolation scheme involved an acid precipitation of tissue extract, DEAE-cellulose and Sephadex G-200 chromatography, and isoelectric focusing. The end product represented about a 1000-fold purification and about a 10% recovery. The purified enzyme was the major isoenzyme, which represented 60% of cathepsin D present in porcine spleen. Two minor isoenzymes of cathepsin D were present in small amounts. The purified enzyme resembled porcine pepsin in molecular weight (35,000), amino acid composition, and inactivation by specific pepsin inactivators. The pH activity curve of the purified enzyme showed two optima near pH 3 and 4. The relative activities at these optimal pH values were affected by salt concentration. Experimental evidence indicated that the two-optima phenomenon is a property of a single enzyme species.     

Purification and properties of cysteine proteinase inhibitors from rabbit skeletal muscle

Two cysteine proteinase inhibitors, CPI-L and CPI-H, were purified from rabbit skeletal muscle by means of successive extraction with a neutral buffer solution, precipitation at pH 3.7, acetone fractionation and gel permeation on Sephadex G-75 and affinity chromatography on carboxymethyl-papain-Sepharose. The molecular mass of CPI-L was 13 kDa on gel permeation chromatography and SDS-PAGE under reducing conditions and was 15 kDa on SDS-PAGE under non-reducing conditions. The molecular mass of CPI-H was 23 kDa on gel permeation chromatography and it was converted to 13 kDa by SH-reducing agent. Although CPI-H showed single protein band with 13 kDa on SDS-PAGE under reducing conditions, it showed four protein bands with 21, 20, 15 and 13 kDa on SDS-PAGE under non-reducing conditions. Therefore, CPI-H was suggested to have a complicated subunit structure for which S-S bonds and some non-covalent bonds would be responsible. CPI-L and CPI-H were stable in the range of pH 3.0-9.5 and up to 80 degrees C. CPI-L and CPI-H were suggested to inhibit cathepsins B, H and L by a non-competitive mechanism. The inhibition constants (Ki) of CPI-L and CPI-H showed that both CPIs have much higher affinity against cathepsins H and L than against cathepsin B.     

Isolation and characterization of a cDNA encoding a mammalian cathepsin L-like cysteine proteinase from Acanthamoeba healyi

We have cloned a cDNA encoding a cysteine proteinase of the Acanthamoeba healyi OC-3A strain isolated from the brain of a granulomatous amoebic encephalitis patient. A DNA probe for an A. healyi cDNA library screening was amplified by PCR using degenerate oligonucleotide primers designed on the basis of conserved amino acids franking the active sites of cysteine and asparagine residues that are conserved in the eukaryotic cysteine proteinases. Cysteine proteinase gene of A. healyi (AhCP1) was composed of 330 amino acids with signal sequence, a proposed pro-domain and a predicted active site made up of the catalytic residues. Cys25, His159, and Asn175. Deduced amino acid sequence analysis indicates that AhCP1 belong to ERFNIN subfamily of C1 peptidases. By Northern blot analysis, no direct correlation was observed between AhCP1 mRNA expression and virulence of Acanthamoeba, but the gene was expressed at higher level in amoebae isolated from soil than amoeba from clinical samples. These findings raise the possibility that Ahcp1 protein may play a role in protein metabolism and digestion of phagocytosed bacteria or host tissue debris rather than in invasion of amoebae into host tissue.     

A cysteine proteinase secreted from human breast tumours is immunologically related to cathepsin B.

The stable cathepsin B-like cysteine (thiol) proteinase secreted from human breast tumours in culture was shown to be destabilized by mercurial compounds. After such treatment the enzyme cross-reacts in a radioimmunoassay with a monospecific antiserum to human liver cathepsin B. It is suggested that the secreted enzyme may be a precursor form of lysosomal cathepsin B.     

Further characterization of cysteine proteinase inhibitors purified from rat and human epidermis

Cysteine proteinase inhibitors isolated from rat and human epidermis were purified to homogeneity and had isoelectric points of pH 4.31 and pH 5.10, respectively, Both inhibitors caused noncompetitive inhibition to the same degree against papain (EC 3.4.22.2), but the activity of human inhibitor against rat liver cathepsins B (EC 3.4.22.1), H (EC 3.4.22.16), and L (EC 3.422.-) was more effective than that of rat inhibitor. Dependency on pH was observed with rat inhibitor for cathepsins B and H, and with human inhibitor for cathepsin L. The reaction of the inhibitors with papain and cathepsins H and L occurred immediately, while the inhibition reaction of cathepsin B increased progressively during a preincubation time up to 40 min. Incubation at pH 7.0 maximized the progressive inhibitory activity. These findings demonstrate that cysteine proteinase inhibitors from rat and human epidermis inhibited a variety of cysteine proteinases. However, the inhibitor and enzyme interaction depends upon the enzyme, inhibitor source, and experimental conditions such as pH and preincubation time.     

Isolation and properties of neutral SH-dependent proteinase from bovine spleen]

A neutral SH-dependent proteinase was isolated from bovine spleen by a slight modification of the previous method (1) and its action on some natural and synthetic substrates was studied. The activity of the enzyme was increased 2000--2500-fold as compared to that of the original extract. The enzyme hydrolyzed various histones (H1, H2a, H2b, H3), casein and protamine but did not split hemoglobin, serum albumin and 14C-tryptophane-labelled total protein from chicken embryos. The enzyme possessed neither collagenolytic nor elastase activity; it did not inactivate aldolase, hexokinase, glyceraldehyde phosphate dehydrogenase and glucose-6-phosphate dehydrogenase, which makes the enzyme different from cathepsin B1 and some other previously described proteinases. The enzyme did not split BAPA, BAEE, ATEE, Boc-Ala-ONP, Leu-beta-NA and some other peptides. The molecular weight of the enzyme was found to be about 15 000.     

马铃薯腐烂茎线虫L 型半胱氨酸蛋白酶新基因(Dd-cpl-1) 的克隆与序列分析

L型半胱氨酸蛋白酶基因 (Cathepsin L-like cysteine proteinase gene) 为与植物寄生线虫寄生能力相关的多功能基因。运用RT-PCR和RACE的方法从马铃薯腐烂茎线虫Ditylenchus destructor中克隆出1个L型半胱氨酸蛋白酶新基因Dd-cpl-1 (GenBank登录号为GQ180107)。该基因Dd-cpl-1 cDNA全长序列含有1个1 131 bp的开放性阅读框 (ORF),编码376个氨基酸残基,其5′末端及3′末端分别含有29 bp和159 bp的非编码区 (UTR)。Dd-cpl-1内含子外显子结构分析结果表明,其基因组序列包含7个内含子,且各内含子两端剪接位点序列遵守GT/AG规则。Dd-cpl-1基因推定的蛋白Dd-CPL-1与松材线虫L型半胱氨酸蛋白酶高度同源,一致性达到77％。以不同物种中L 型半胱氨酸蛋白酶氨基酸序列进行比对分析,推测推定的蛋白 Dd-CPL-1含有L型半胱氨酸蛋白酶基因家族高度保守的催化三联体 (Cys183,His322 和Asn343) 以及ERFNIN基系和GNFD基系。半胱氨酸蛋白酶系统发育分析表明,Dd-cpl-1 属于由L型半胱氨酸蛋白酶组成的进化分支。Dd-cpl-1的这些序列特征进一步表明其为L型半胱氨酸蛋白酶基因。这是首次在马铃薯腐烂茎线虫中克隆到的L型半胱氨酸蛋白酶,为今后在蛋白水平对其进行进一步的功能分析提供基础。     

Determination of the mRNA sequence of cathepsin Y,a cysteine endopeptidase from rat spleen, 1 and confirmation of its ubiquitous expression

A cysteine endopeptidase from rat spleen was purified, characterized and its gene cloned. This enzyme was originally recognized by its action of producing kinin-potentiating peptide from a plasma protein. We named it cathepsin Y due to its localization, acidic pH optimum and the presence of the same set of active site amino acids as in other thiol cathepsins. Here we show the total sequence of the mRNA obtained by means of TaKaRa 5' Full RACE Core Set and complete the previously reported sequence. This completion of the mRNA sequence resulted in the omission of the strangely attached C-terminal peptide from cathepsin Y.     

Purification and some properties of buffalo spleen cathepsin B

Purification of cathepsin B from buffalo-spleen, a hitherto unstudied system has been achieved by a simple procedure developed by incorporating suitable modifications in the existing methods for isolation of the enzyme from other sources. The purified enzyme has a molecular weight of 25 KDa and its Stokes radius was found to be 2·24 nm. Effects of several reducing agents, urea and thiol-protease inhibitors such as leupeptin and antipain, have been studied and the data unequivocally support the contention that the buffalo-enzyme is similar to cathepsin B from other tissues with respect to these properties.     

Inhibitory properties of low molecular mass cysteine proteinase inhibitors from human sarcoma

Elevated activities of cysteine proteinases such as cathepsins B and L and cancer procoagulant have been linked to tumor malignancy. In the present study we examined the hypothesis that these elevated activities could be due to impaired regulation by the endogenous low molecular mass cysteine proteinase inhibitors (cystatins). Inhibitors from human sarcoma were compared to those from human liver, a normal tissue in which the inhibitors had been characterized previously. An extract of cystatins from sarcoma was less effective against papain and cathepsin B (liver or tumor) than was an extract from liver. This reduced inhibitory capacity in sarcoma was not due to a reduction in either the concentrations or specific activities of the cystatins or an absence of any family or isoform of cystatins. We purified two members of the cystatin superfamily (stefin A and stefin B) to homogeneity and determined their individual inhibitory properties. Stefins B from liver and sarcoma exhibited comparable inhibition of papain and cathepsin B. In contrast, stefin A from sarcoma exhibited a reduced ability to inhibit papain, human liver cathepsins B, H and L and human and murine tumor cathepsin B. The Ki for inhibition of liver cathepsin B by sarcoma stefin A was 10-fold higher than that for inhibition of liver cathepsin B by liver stefin A, reflecting a reduction in the rate constant for association and an increase in the rate constant for dissociation. Cancer is now the third pathologic condition reported to be associated with alterations in cystatins, the other two being amyloidosis and muscular dystrophy.     

Characterization of a latent cysteine proteinase from ascitic fluid as a high molecular weight form of cathepsin B

The latent cysteine proteinase present in ascitic fluid of patients with neoplasia and released from ascites cells in culture has been partially purified and the enzyme after pepsin activation was shown to be immunologically related to the lysosomal proteinase, cathepsin B. The latent form was characterized as a single chain of M_r 40 000 as determined by SDS-polyacrylamide gel electrophoresis under reducing conditions followed by Western blotting and immune staining with an antiserum to human cathepsin B. Using the same techniques the enzyme after pepsin activation gave a single band of M_r 33 000. Analysis by isoelectric focusing showed that the latent enzyme before and after pepsin treatment is composed of several acidic isoenzymes. These findings suggest that this latent proteinase represents a precursor form of cathepsin B which is released extracellularly rather than being processed and directed to the lysosome.     

Cathepsin S. The cysteine proteinase from bovine lymphoid tissue is distinct from cathepsin L (EC 3.4.22.15).

Cathepsin S was purified from bovine spleen by acid autolysis, (NH4)2SO4 fractionation and chromatography on CM-Sephadex C-50, CM-cellulose and activated-thiol-Sepharose. Cathepsin L was isolated from lysosomal fractions of rat liver, rat kidney and bovine liver. Generally, cathepsin L was bound tightly to CM-Sephadex C-50. Preparations of cathepsin L from rat liver, rat kidney and bovine liver were shown to have kinetic constants for the substrate benzyloxycarbonyl-Phe-Arg-7-(4-methyl)coumarylamide in the same range (Km 2-3 microM). Benzyloxycarbonyl-Phe-Phe-diazomethane proved to be a sensitive irreversible inhibitor of cathepsin L from different species. Cathepsin S differed in all these characteristics from cathepsin L. A polyclonal antibody to cathepsin L from rat reacted with bovine cathepsin L but not with bovine cathepsin S.