Biomedical subjects

T Tadakuma

Publications and source records attributed to T Tadakuma.

At least 19 recordsLinked to original sources

PubMed2002

Different role of Apaf-1 in positive selection, negative selection and death by neglect in foetal thymic organ culture.

Apoptotic protease-activating factor 1 (Apaf-1) is a component of the apoptosome which is required for the activation of procaspase-9. As Apaf-1 knockout (KO) (Apaf-1-/-) mice die before birth, the role of Apaf-1 during thymic selection was investigated using 5 day foetal thymic organ culture (FTOC) of thymi obtained at gestational day 15. There was a lower ratio of CD4 single-positive (SP) to CD8 SP cells and decreased apoptosis of CD4+CD8+ (DP) thymocytes from Apaf-1-/- mice compared with wild-type. To determine if these defects resulted in increased production of neglected thymocytes, the Apaf-1-/- mice were crossed with the T-cell receptor (TCR)-alpha-chain KO mice. There was no difference in thymocyte development in the thymi of TCR-alpha-/-Apaf-1-/- and TCR-alpha-/-Apaf-1+/+ mice 5 days after FTOC. To determine if Apaf-1 is involved in apoptosis during death by negative or positive selection, FTOC of the thymus of Apaf-1-/- Db/HY TCR-alphabeta transgenic (Tg) mice was carried out. There was decreased apoptosis of the HY clonal-specific M33+ thymocytes and an increased percentage of the autoreactive CD8+M33+ thymocytes in male, but not female Apaf-1-/- Db/HY TCR Tg mice. Our data suggest that Apaf-1 is not involved in positive selection or death by neglect, but may have a partial role in negative selection during early thymic T-cell development.

Animals↗

PubMed2001

Coexpression of the partial androgen receptor enhances the efficacy of prostate-specific antigen promoter-driven suicide gene therapy for prostate cancer cells at low testosterone concentrations.

The prostate specific antigen (PSA) promoter/enhancer has been clearly demonstrated to be tissue specific, and has been applied to prostate-specific gene therapy. However, the transcription of the PSA gene is strictly androgen dependent, and its promoter activity is very weak at low concentrations of testosterone, which are generally observed in prostatic cancer patients treated with androgen deprivation. In this study, we used a partial androgen receptor (ARf) containing amino acids 232-429 and 481-657 to transactivate the PSA gene without androgens. We made two expression vectors, ARfPPLUC and ARfPPTK. They contained ARf cDNA driven by cytomegalovirus promoter and cDNAs of either firefly luciferase (LUC) or herpes simplex virus thymidine kinase (TK) driven by PSA promoter/enhancer (PP). The expressed ARf enhanced the PP activity by about 110-fold in the PSA-producing prostate cancer cell line, LNCaP, under low testosterone concentrations. Moreover, in a PSA-nonproducing prostate cancer cell line, DU145, ARf also enhanced the PP activity by about 60-fold in an androgen-independent manner. In a growth inhibition assay, ARfPPTK treated with ganciclovir was found to inhibit the cell growth of LNCaP cells much more effectively than PPTK. Furthermore, in contrast to PPTK, ARfPPTK also had an inhibitory effect on DU145 cells. This system is thus considered to provide a useful therapeutic option in patients with prostate cancer who are receiving hormonal therapy.

Cell Division↗

PubMed2001

A single intradermal administration of soluble leishmanial antigen and plasmid expressing interleukin-12 protects BALB/c mice from Leishmania major infection.

In murine leishmaniasis, the induction of the T-helper type 1 (Th1) response contributes to infection resistance, whereas the establishment of the Th2 response makes the mice susceptible to infection. Interleukin-12 (IL-12) plays a pivotal role in the diversification of immune responses to the Th1 type. In this study, we tested whether the co-administration of IL-12 expression plasmid which compose p35 and p40 subunits and soluble leishmanial antigen (SLA) will skew the susceptible BALB/c mice to Th1 response and protect from leishmaniasis. When the mice were intradermally injected with the combination of IL-12 plasmid and SLA 7 days prior to the challenge with 1x10(6) promastigotes of Leishmania major, the local lesions completely healed and the parasite burden in the local lymph nodes significantly decreased. The cured mice attained long-term immunity, and were resistant to any subsequent rechallenge of the lethal dose of the parasite. The protective effect was associated with the development of a Th1 response, as demonstrated by the enhanced level of antigen-specific interferon-gamma (IFN-gamma) and dominant production of IgG2a in the serum. In contrast, the administration of empty plasmid plus SLA or IL-12 plasmid alone failed to protect the disease and shape the Th1 response. Furthermore, the protective efficiency induced by the vaccination was clearly prevented by the injection of either neutralizing anti-IL-12 mAb or anti-IFN-gamma mAb. The IL-12 expression plasmid is thus an effective adjuvant for the elicitation of a protective Th1 response against leishmaniasis and is therefore, considered to be appropriate for vaccinations that require the induction of Th1 type immunity.

Animals↗

PubMed2001

Suicide gene therapy on LNCaP human prostate cancer cells.

The efficacy of combination suicide gene therapy was evaluated using a Herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) system and an Escherichia coli cytosine deaminase/5-fluorocytosine (CD/5-FC) system on the LNCaP human prostate cancer cell model. Two types of plasmid vectors with the HSV-TK gene were constructed. A constitutive chicken beta-actin promoter drove one and a prostate-specific antigen (PSA) promoter drove the other. Similarly, a pair of plasmids with the CD gene under a cytomegalovirus (CMV) promoter and the PSA promoter was also constructed. LNCaP cells were transfected in vitro with either or both of those plasmids using a cationic lipid reagent. Transfected cells were treated with GCV and/or 5-FC. The percentage of viable LNCaP cells 7 days after treatment with HSV-TK/GCV or CD/5-FC under a constitutive promoter was 40% and 41% of controls, respectively. The cell viability when two suicide genes were combined was 23%. The cell viabilities after four days with PSA promoter-HSV-TK vectors, CD vectors and a combination of both were 79%, 88% and 88%, respectively. Suicide gene therapy using either HSV-TK/GCV, CD/5-FC, or both, was effective in the LNCaP model. An additive effect was observed when the two suicide genes were used together. The PSA promoter did not seem to be effective enough to elicit cytotoxicity under the experimental conditions used here.

Antimetabolites↗

PubMed2001

Liposome-mediated gene therapy using HSV-TK/ganciclovir under the control of human PSA promoter in prostate cancer cells.

To more accurately determine the tissue-specific expression of the target gene in prostate cancer cells, we introduced the enhancer element (-4,777 to -3,934; PSAR) and the promoter region (PSAP) of the prostate-specific antigen (PSA) gene. Furthermore, to elucidate the advantages of using liposomes as a gene carrier, we screened more than 20 liposome preparations in this study. The 5' upstream region of PSA gene (PSARPSAP) was conjugated to either the chloramphenicol acetyltransferase (CAT) gene or herpes simplex virus thymidine kinase (TK) gene, and the transfection of these plasmids was carried out using cationic liposomes, DMRIE-C (Gibco) or LipoTAXI (Stratagene). The expression of CAT activity was clearly observed when PSARPSAP-CAT plasmid was transfected into PSA-positive LNCaP cells, whereas no CAT activity was detected in PSA-negative DU145 cells or bladder carcinoma T24 cells. The CAT activity increased after the addition of testosterone. We then evaluated the therapeutic effect of the PSARPSAP-TK plasmid in vitro. When PSARPSAP-TK plasmid was transfected and ganciclovir was added to the medium, the growth of LNCaP cells was inhibited, while no growth inhibition was observed in DU145 cells. Furthermore, this inhibitory effect was observable even when the cells were cultured in a medium supplemented with dialyzed fetal bovine serum. These results suggest that the liposome-mediated transfection of PSARPSAP-TK appears to be a potentially effective approach for selecting the optimal treatment for tumor cells producing PSA even with the low androgen levels seen in patients treated by anti-androgen therapy.

Ganciclovir↗

PubMed2000

Inhibition of glucocorticoid-induced apoptosis by the expression of antisense gene of mitochondrial ATPase subunit 6(1).

To isolate the apoptosis-linked genes involved in the cell death of thymocytes induced by glucocorticoids, we developed a functional cloning assay. Murine CD4(+)CD8(+) thymic cell line 2-257-20 cells were transfected with cDNA expression libraries obtained from a dexamethasone-resistant cell line. The transfected cells were selected in the presence of dexamethasone, and the plasmids which episomally expanded were then extracted from the surviving cells. One of the rescued cDNAs was found to be an antisense cDNA fragment identical to the mouse mitochondrial ATPase 6 gene. In the stable transfectants with the ATPase 6 antisense gene, the induction of apoptosis by dexamethasone was significantly delayed. Furthermore, the ATP synthesis in these transfectants was also reduced to some extent. ATPase 6 is a subunit of F(o)F(1) ATPase and our results support that ATP synthesis from the mitochondria is necessary for the induction of apoptosis induced by glucocorticoids.

Adenosine Triphosphatases↗

PubMed2000

Mouse CD8+ CD122+ T cells with intermediate TCR increasing with age provide a source of early IFN-gamma production.

Although CD8+ IL-2Rbeta (CD122)+ T cells with intermediate TCR reportedly develop extrathymically, their functions still remain largely unknown. In the present study, we characterized the function of CD8+ CD122+ T cells with intermediate TCR of C57BL/6 mice. The proportion of CD8+ CD122+ T cells in splenocytes gradually increased with age, whereas CD8+ IL-2Rbeta-negative or -low (CD122-) T cells conversely decreased. The IFN-gamma production from splenocytes stimulated with immobilized anti-CD3 Ab in vitro increased with age, whereas the IL-4 production decreased. When sorted CD8+ CD122+ T cells were stimulated in vitro by the anti-CD3 Ab, they promptly produced a much larger amount of IFN-gamma than did CD8+ CD122- T cells or CD4+ T cells, whereas only CD4+ T cells produced IL-4. The depletion of CD8+ CD122+ T cells from whole splenocytes greatly decreased the CD3-stimulated IFN-gamma production and increased the IL-4 production, whereas the addition of sorted CD8+ CD122+ T cells to CD8+ CD122+ T cell-depleted splenocytes restored the IFN-gamma production and partially decreased IL-4 production. It is of interest that CD8+ CD122+ T cells stimulated CD4+ T cells to produce IFN-gamma. The CD3-stimulated IFN-gamma production from each T cell subset was augmented by macrophages. Furthermore, CD3-stimulated CD8+ CD122+ T cells produced an even greater amount of IFN-gamma than did liver NK1.1+ T cells and also showed antitumor cytotoxicity. These results show that CD8+ CD122+ T cells may thus be an important source of early IFN-gamma production and are suggested to be involved in the immunological changes with aging.

Aging↗

PubMed2000

The potential role for nephritis-associated plasmin receptor in acute poststreptococcal glomerulonephritis.

Immunoglobulin G from a patient convalescing from acute poststreptococcal glomerulonephritis (APSGN) bound specific antigenic sites in early APSGN glomeruli. A streptococcal cytoplasmic antigen (preabsorbing antigen, PA-Ag), could selectively preabsorb fluorescein isothiocyanate (FITC)-labeled IgG and prevented glomerular staining. The antigen was purified and identified as an M(r) approximately 43,000 protein with a pI of 4.7 that strongly activated complement C3 (N. Yoshizawa, S. Oshima, I. Sagel, J. Shimizu, and G. Treser, 1992, J. Immunol. 148, 3110-3116). In the present study, a nephritogenic antigen was purified by affinity chromatography using APSGN IgG-immobilized Sepharose followed by chromatography on an anion-exchange resin. Purification was monitored by ELISA and Western blotting using the binding characteristics of the specific antibodies present in APSGN serum. The molecular weight of the purified antigen, named nephritis-associated plasmin receptor (NAPlr), was an M(r) approximately 43,000 protein and the internal amino acid sequence was found to be homologous to those of the plasmin receptor (Plr) of group A streptococci strain 64/14 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from Bacillus subtilis. The purified NAPlr exhibited GAPDH activity and plasmin(ogen) binding activity. Using FITC-labeled rabbit anti-NAPlr, the antigen was found to be present in the glomeruli of 22 of 22 patients in the early stage of APSGN. Bacterial Plr was also demonstrated in human APSGN glomeruli for the first time using monoclonal antibody to the recombinant Plr protein. Antibody to NAPlr was found in the sera of 46 of 50 (92%) patients within 3 months of onset. These results led us to speculate that NAPlr bound to the glomeruli may contribute to the pathogenesis of APSGN via plasmin and complement activation.

Adult↗

PubMed2000

Selective inhibition of hepatoma cells using diphtheria toxin A under the control of the promoter/enhancer region of the human alpha-fetoprotein gene.

We constructed a plasmid containing human alpha-fetoprotein (AFP) promoter/enhancer to direct the cell type-specific expression of diphtheria toxin fragment A (DTA), designated as pAF-DTA, to AFP-producing hepatocellular carcinoma cells. The transfection was carried out with cationic liposomes (DMRIE-C) and the expression of the DTA gene was confirmed by a northern blot analysis. When pAF-DTA was transfected, the growth of AFP-positive HuH-7 cells was inhibited, whereas growth inhibition was not observed in AFP-negative MKN45 cells. In this experiment, the secretion of AFP was similarly suppressed, but the secretion of carcinoembryonic antigen from MKN45 was not altered. pAF-DTA could also exert its growth inhibitory effect on PLC, a cell line with a low level of AFP. However, no inhibitory effect of pAF-DTA was observed on the proliferation of primary hepatocyte cells. Furthermore, transfection experiments in which HuH-7 and splenic stromal cells were co-cultured revealed the growth inhibition by pAF-DTA to be selective in HuH-7 cells. Finally, the growth of HuH-7 transplanted on BALB/c nu/nu mice was inhibited by the direct injection of pAF-DTA/liposome complex into a tumor mass. These results suggest that use of pAF-DTA may be potentially useful as a novel approach for the selective treatment of tumor cells producing AFP even at low levels, without affecting other types of cells.

Animals↗

PubMed1999

Cell-specific expression of the diphtheria toxin A-chain coding sequence under the control of the upstream region of the human alpha-fetoprotein gene.

BACKGROUND AND OBJECTIVES: Development of the system to express a suicide gene selectively in tumor cells is essential for gene therapy. We constructed a plasmid containing the diphtheria toxin A (DTA) fragment linked to human alpha-fetoprotein (AFP) promoter and enhancer, and tested whether it can exert its cytocidal effect selectively on AFP-producing cells. METHODS: The chloramphenical acetyltransferase (CAT) reporter gene or DTA gene was linked to the 5' upstream region of the AFP gene. The plasmids were transfected into AFP-producing or non-producing cells by the lipopolyamine-coated DNA method. Expression of CAT activity and effects on cell growth of transfected cells were assessed. RESULTS: When the AFP-producing cells HuH-7 or HepG2 were cotransfected with CAT reporter plasmid and pAF5.1DTA plasmid, the CAT activity was greatly suppressed. In contrast, cotransfection with pAF5.1DTA-R, the inversely inserted DTA gene, did not inhibit CAT activity. Furthermore, cell growth of HuH-7 cells transfected with pAF5.1DTA plasmid was significantly inhibited compared with HuH-7 cells transfected with DTA-R plasmid. CONCLUSIONS: Our results indicate that selective killing of AFP-producing cells will be attained by introducing the DTA gene linked to the promoter and enhancer region of AFP.

Carcinoma, Hepatocellular↗

PubMed1998

Molecular cloning of ssd-form neural cell adhesion molecules (N-CAMs) as the major form in Xenopus heart.

Different forms of neural cell adhesion molecule (N-CAM) are generated by alternative splicing of primary transcripts and considered to have distinct biological functions. We cloned cDNAs encoding a new form of N-CAMs from the Xenopus heart cDNA library. Comparison of the sequences with chicken and mouse N-CAMs revealed that these clones code for ssd-form N-CAM. We demonstrate by Northern blot analysis that the ssd form is the major form expressed in the Xenopus adult heart. We obtained two types of ssd-form N-CAM, which are transcripts from N-CAM 1 and N-CAM 2 genes. Both types contain muscle specific domain (MSD) but not pi domain. Northern blot analysis also indicated that this form is not expressed in adult brain, in which ld-form N-CAM is the main N-CAM expressed. It is possible that high levels of specific expression of ssd-form N-CAM are related with the differentiation of cardiac muscles.

Amino Acid Sequence↗

PubMed1998

Inhibitory effect of protease inhibitor on endothelial cell activation.

BACKGROUND: Endothelial cells (EC) are important for regulating the hemostatic balance of prothrombotic and antithrombotic activities. Proinflammatory cytokines such as tumor necrosis factor-alpha (TNFalpha) play an important role in the regulation of EC and also regulate the production of plasminogen activator inhibitor type 1 (PAI-1), which is an EC-producing factor with the inhibitory activity of fibrinolysis, and the expression of intercellular adhesion molecule-1 (ICAM-1), which is an adhesion molecule that plays an important role in inflammation. Protease inhibitors such as gabexate mesilate (GM) and ulinastatin (UTI) have been shown to improve the microcirculatory environment and reduce tissue damage, but the mechanism for this has yet to be fully elucidated. We investigated the effect of GM or UTI on EC regarding PAI-1 synthesis and ICAM-1 expression. METHODS: Human umbilical vein endothelial cells (HUVECs) were obtained and stimulated with TNFalpha. GM or UTI was added to HUVECs just before TNFalpha stimulation. The PAI-1 activity in the culture medium of HUVECs was measured by using an enzymatic assay kit. The PAI-1 mRNA expression was assayed by a semiquantitative reverse transcriptase polymerase chain reaction assay. The ICAM-1 expression on HUVECs was assayed by a flow cytometric analysis. RESULTS: GM inhibited the PAI-1 synthesis of HUVECs stimulated with TNFalpha in a dose-dependent manner as shown by the mRNA expression. However, UTI was not able to inhibit PAI-1 synthesis. In contrast, both GM and UTI significantly inhibited the ICAM-1 expression on HUVECs stimulated with TNFalpha. CONCLUSIONS: These data suggest that GM may thus provide a beneficial effect which improves the microcirculatory environment and prevents tissue damage by inhibiting the activation of the vascular EC themselves.

Base Sequence↗

PubMed1998

Carbonic anhydrase I and II as a differentiation marker of human and rat colonic enterocytes.

Carbonic anhydrase (CA) is an enzyme that is expressed in the intestine and catalyzes the reversible hydration of CO2 in the following reaction: CO2 + H2O<==>H2CO3<==>H(+)+HCO3-. To elucidate the association of CA expression with the differentiation of colonic enterocytes, we investigated the expression and localization of CA using a Northern blotting analysis, Western blotting analysis, and immunohistochemical staining. A Northern blotting analysis revealed an abundant expression of CA I and II mRNA in the colonic epithelial cells. However, the expression of CA III mRNA was not detected. According to the results of immunohistochemical staining of the human colonic mucosa using antisera against CA I and II, both CA I and II were localized on the cytoplasm of non-goblet columnar cells in the upper half of the crypts where more differentiated cells are located. According to the results of immunohistochemical staining of the rat colonic mucosa, neither CA I and II were detected at the new-born stage. The expression of CAs in the upper half of the crypts began to rise from 1 week after birth, and thereafter increased according to the growth of the rats. At 3 weeks after birth, the expression of CAs was almost the same as that of the adult rats. The amount of CA proteins evaluated by a Western blotting analysis revealed that the expression of CAs increased gradually until reaching a maximum level at 6 or 8 weeks. These results therefore suggest that CA I and II appear to be good markers for the differentiation of enterocytes in the colonic mucosa.

Animals↗

PubMed1998

Enhancement of activation-induced cell death by fibronectin in murine CD4+ CD8+ thymocytes.

Development of T cells in the thymus is achieved through the interactions of thymocytes with their microenvironments. This study focused on the function of fibronectin (FN), a major extracellular matrix molecule in the thymus, in the cell death induced by activation via the T-cell antigen receptor. FN alone did not increase cell death in murine thymocytes above the baseline level, but it significantly enhanced the cell death induced by fixed anti-CD3 monoclonal antibody (mAb), especially when a high concentration of anti-CD3 mAb was used. DNA fragmentation increased in parallel with cell death, indicating that cell death was a result of the apoptosis. Fluorescence-activated cell sorter (FACS) analysis revealed that the activation-induced cell death (AICD) caused by anti-CD3 mAb alone, or by a combination of anti-CD3 mAb and FN, occurred selectively in CD4+ CD8+ thymocytes. Very late activation antigen (VLA)-4 and VLA-5 are two major ligands to FN on thymocytes. The expression of both ligands was investigated at different stages of thymocyte development. VLA-4 was predominantly expressed at the CD4- CD8- stage, and thereafter the expression was reduced, whereas VLA-5 was constantly expressed during maturation. Furthermore, the enhancing effect by FN was inhibited in the presence of the Gly-Arg-Gly-Asp-Ser-Pro (GRGDSP) peptide but not in the presence of the connecting segment-1 (CS-1) peptide, suggesting that enhancement of AICD observed in CD4+ CD8+ thymocytes is mediated through VLA-5.

Animals↗

PubMed1998

Cloning and expression of an alpha-2,8-polysialyltransferase (STX) from Xenopus laevis.

Polysialic acid (polySia) is a carbohydrate structure found on neural cell adhesion molecules (N-CAM). Two polysialyltransferases (polySiaTs) that catalyze synthesis of polySia have been described, and designated PST-1/PST/ST8SiaIV and STX/ST8SiaII. We cloned a polySiaT (xSTX) from a nonmammalian vertebrate, Xenopus laevis . xSTX had 80% amino acid similarity to the rat STX. This clone induced polySia expression when transfected into polySia-negative COS-1 cells. Northern blot analysis of whole embryos at different stages of development revealed that xSTX mRNA was most abundantly expressed in premetamorphic stages. The relative level of xSTX and N-CAM mRNAs was also examined and found to change in parallel to the extent of polysialylation on N-CAM. In adult tissues, the expression of xSTX mRNA was restricted to brain, eye and heart, which also expressed polySia. These results suggest that xSTX is the major enzyme responsible for the synthesis of polysialylated N-CAM in embryos at certain stages of development and also in adult tissues.

Amino Acid Sequence↗

PubMed1997

[Molecular mechanism of apoptosis operated in the immune system].

Apoptosis is the physiological cell death, and plays an important role in the various fields of immunology, especially (1) in the formation of T cell and B cell repertoires, (2) in the regulation of hyper-activated T and B cells by Fas-FasL, and (3) in the effector phases of eliminating potentially dangerous cells. Although, the exact mechanism of cell death is still unknown, progress has been made in identifying key elements in apoptosis. Particularly, ICE family was found essential for apoptotic execution, and Bcl-2 related proteins can block the molecular events of apoptosis. This article briefly reviewed such "on" and "off" signals in apoptosis, and discussed from the view point that the disturbance of the balance of these signals are relevant to the etiology of autoimmune diseases.

Animals↗

PubMed1996

Improvement of pharmacokinetics and antitumor activity against human hepatoma cell line by using adriamycin-entrapped stealth liposomes.

Preferential accumulation in the reticuloendothelial system is one of the major obstacles to the use of liposomes as a drug carrier for targeting therapy. To reduce their uptake, ganglioside GM1 was introduced into the components of conventional liposomes that had been used in our targeting experiments. Two types of such liposomes were prepared. Tissue distribution studies on Adriamycin entrapped in both types of liposomes clearly indicated that the uptake of Adriamycin by liver and spleen decreased to the level comparable to that of free Adriamycin administration. By contrast, the level of Adriamycin in the serum remains high, and some increase was observed in the accumulation to the tumor. Furthermore, Adriamycin in these liposomes, which were conjugated with anti-alpha-fetoprotein (AFP) antibody, inhibited the growth of AFP-positive human hepatoma Li-7 more efficiently than free Adriamycin or Adriamycin in antibody-conjugated conventional liposomes.

Animals↗

PubMed1995

Purification and characterization of acid cysteine protease from metacercariae of the mammalian trematode parasite Paragonimus westermani.

Acid cysteine protease was purified from metacercariae of the mammalian trematode parasite Paragonimus westermani. The purified enzyme had a molecular mass of 27 kDa and was a monomeric polypeptide. The protease had an absolute requirement for a reducing agent for full activity towards fluorescein-isothiocyanate-labeled hemoglobin, and it was active in the acidic pH range, with an optimum pH of 4.0. While acidic proteolysis was insensitive to the aspartic protease inhibitor pepstatin A, activity was significantly inhibited by the cysteine protease inhibitors, leupeptin, chymostatin and L-trans-epoxy-succinyl-L-leucylamido(4-guanidino)-butane. The sensitivity of the enzyme to the inhibitors was similar to that of cathepsins B and L, but the specificity of the protease towards chromogenic substrates was slightly different from that of the cathepsins. The purified enzyme was highly specific for N-substituted peptidyl substrates containing arginine in the P1 position and phenylalanine in the P2 position, and the protease extensively degraded human native proteins, such as human serum albumin, immunoglobulins, complement components and also endogenous protease inhibitors. Since the protease hydrolyzes both soluble proteins and components of human defense systems, it may facilitate parasite nutrition and evasion of host defense mechanisms.

Amino Acid Sequence↗