Biomedical subjects

Y Abiko

Publications and source records attributed to Y Abiko.

At least 55 records · Page 3Linked to original sources

PubMed2000

Bactericidal activity of a monoclonal antibody against a recombinant 40-kDa outer membrane protein of Porphyromonas gingivalis.

BACKGROUND: We have cloned the gene for a 40-kDa outer membrane protein (40-kDa OMP) from Porphyromonas gingivalis 381. The recombinant (r)40-kDa OMP has become the subject of considerable interest because of its potential role in the development of a vaccine useful for passive immunization. To develop such a vaccine, it is essential to fully understand the functions of anti-r40-kDa OMP antibody in the host defense against P. gingivalis. To that end, we developed a panel of monoclonal antibodies by immunizing mice with purified r40-kDa OMP. The objective of this study was to determine the bactericidal activity on P. gingivalis by the IgG1 monoclonal antibody Pg-ompA2. METHODS: Bacterial growth measurement, a complement-mediated anti-P. gingivalis assay based on [3H]thymidine uptake, and a 14C-release assay were performed to test the bactericidal activity of Pg-ompA2 to P. gingivalis. RESULTS: In the presence of complement, Pg-ompA2 was lethal to P. gingivalis 381 as well as to the more virulent P. gingivalis strains, including ATCC 53977 and W83. Using component-deficient complement, we determined that Pg-ompA2 killed P. gingivalis by activating both the classical and alternative complement pathways. CONCLUSIONS: Pg-ompA2 has an in vitro complement-mediated bactericidal activity to P. gingivalis. Pg-ompA2 may contribute to the development of a local immunotherapy that can be applied in the gingival crevice of a patient with P. gingivalis-related periodontitis, or be a vaccine candidate.

Animals↗

PubMed1999

Effects of CP-060S, a novel Ca(2+) channel blocker, on oxidative stress in cultured cardiac myocytes.

The effect of (-)-(S)-2-[3,5-bis(1, 1-dimethylethyl)-4-hydroxyphenyl]-3-[3-[N-methyl-N-[2-(3, 4-methylenedioxyphenoxy)ethyl]amino]propyl]-1,3-thiazolidin- 4-one hydrogen fumarate (CP-060S), a novel Ca(2+) channel blocker, on hydrogen peroxide (H(2)O(2))-induced cytotoxicity was studied in cultured rat cardiac myocytes. The CP-060S effect was compared with that of CP-060R, an optical isomer of CP-060S with a less potent Ca(2+) channel blocking action than CP-060S. H(2)O(2) increased the release of lactate dehydrogenase from cardiac myocytes and decreased the formation of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) (MTT) formazan in cardiac myocytes (i.e., cytotoxic action). Both CP-060S (1 microM) and CP-060R (1 microM) attenuated to a similar extent the foregoing alterations induced by H(2)O(2). On the other hand, 1,3-dimethyl-2-thiourea (10 mM), a scavenger of both H(2)O(2) and hydroxyl radical, also attenuated the H(2)O(2)-induced cytotoxicity whereas diltiazem (10 microM) did not. In an experiment using electron spin resonance (ESR) with 5, 5-dimethyl-1-pyrroline N-oxide (DMPO), a spin-trapping agent, both CP-060S and CP-060R decreased the intensity of DMPO-hydroxyl radical signal concentration dependently. These results suggest that CP-060S protects cardiac myocytes from oxidative stress through its radical scavenging action.

Animals↗

PubMed1999

Pattern of expression of beta-defensins in oral squamous cell carcinoma.

Human beta-defensin (hBD)-1 and hBD-2 are antimicrobial peptides that have been detected in certain types of epithelia, including the skin and oral epithelia. It has been suggested that bacterial infection is an important factor in the process of carcinogenesis. The expression of hBDs in oral squamous cell carcinoma (SCC) may be down-regulated. We studied the pattern of expression of hBD-1 and hBD-2 mRNA in oral (SCC) cell lines and in tumor samples obtained from four patients with oral SCC who underwent surgical resection, by reverse transcription-polymerase chain reaction (RT-PCR). Human gingival epithelial (HGE) cells were used as the control. The effect of various inflammatory cytokines on hBD-1 and hBD-2 expression in the HGE cells and SCC cell lines, was also studied. hBD-1 mRNA was detected in the Ca-9, SCC-9 and HSC-4 cell lines, but not in the SAS and KB cell lines. hBD-2 mRNA was detected in all five cell lines. All four tumor samples expressed both hBD-1 and hBD-2 mRNA, although the mRNA level of each protein varied. These results indicate that SCCs in which hBD expression is downregulated, may be susceptible to bacterial infection.

Aged↗

PubMed1999

Both D-cis- and L-cis-diltiazem attenuate hydrogen peroxide-induced derangements in rat hearts.

The effects of D-cis- and L-cis-diltiazem on the hydrogen peroxide (H2O2)-induced derangements of mechanical function and energy metabolism, and accumulation of intracellular Na+ were studied in isolated rat hearts. The intracellular concentration of Na+ ([Na+]i) in the myocardium was measured using a nuclear magnetic resonance technique. H2O2 (600 microM) increased the left ventricular end-diastolic pressure, decreased the tissue level of ATP, and increased the release of lactate dehydrogenase from the myocardium. These alterations induced by H2O2 were significantly attenuated by D-cis-diltiazem (15 microM) or L-cis-diltiazem (15 microM). H2O2 (1 mM) produced a marked increase in the myocardial [Na+]i, which was effectively inhibited by tetrodotoxin (3 microM), D-cis-diltiazem (15 microM) or L-cis-diltiazem (15 microM). These results suggest that both D-cis- and L-cis-diltiazem protect the myocardium against the H2O2-induced derangements in the isolated, perfused rat heart. The protective action of D-cis- and L-cis-diltiazem may be due to their ability to inhibit the H2O2-induced increase in [Na+]i, at least in part.

Animals↗

PubMed1999

Effect of cellular aging on the induction of cyclooxygenase-2 by mechanical stress in human periodontal ligament cells.

The production of prostaglandin (PGE2) in human periodontal ligament fibroblast (hPLF) cells is increased by mechanical stress, however, the age-related changes in the susceptibility of hPLF cells in response to mechanical stress remain unclear. The purpose of this study was to examine the influence of in vitro cellular aging on PGE2 production and the gene expression of cyclooxygenase (COX) in mechanically stressed hPLF cells. In vitro cellular aged hPLF cells were prepared by sequential subcultivations of hPLF cells from young healthy periodontal ligaments. In vitro cellular aged hPLF cells produced a significantly higher amount of PGE2, as compared with young hPLF cells, when the cells were exposed to cyclic tension force in a time- and magnitude-dependent manner. The COX-2 mRNA level in aged cells was higher than that in young cells, whereas COX-1 mRNA remained unchanged. Since PGE2 from hPLF cells was stimulated by in vitro aging as presented here, aging of hPLF cells may affect the severity of inflammation and bone resorption in the aged through the production of a large amount of PGE2 in response to an excessive force such as a traumatic occlusion.

Cells, Cultured↗

PubMed1999

Sperizin is a murine RING zinc-finger protein specifically expressed in Haploid germ cells.

Through the preparation of a subtracted cDNA library, we have extensively isolated genes whose expression is induced in mouse spermatogenic cells. One of the genes encoded a protein with a RING zinc-finger motif, which we termed sperizin (spermatid-specific ring zinc finger). Transcription of the sperizin gene was not observed in prepubertal testis, but became detectable at day 23. Northern and in situ hybridization analyses indicated that the sperizin gene was exclusively expressed in the round spermatid. The sperizin gene is intronless, and GFP-tagged sperizin was found to be localized in the cytoplasm of ectopically expressed somatic cultured cells. We assigned the chromosomal localization of the sperizin gene to chromosome 17 using an interspecific backcross mapping panel. The data suggest that we have identified a new member of the RING-finger family of proteins that may be involved in spermatogenesis.

Animals↗

PubMed1999

Determination and characterization of the hemagglutinin-associated short motifs found in Porphyromonas gingivalis multiple gene products.

Porphyromonas gingivalis is a Gram-negative anaerobic bacterial species implicated as an important pathogen in the development of adult periodontitis. In our studies of P. gingivalis and ways to protect against periodontal disease, we have prepared the monoclonal antibody mAb-Pg-vc and its recombinant antibody, which are capable of inhibiting the hemagglutinating activity of P. gingivalis (Shibata, Y., Kurihara, K., Takiguchi, H., and Abiko, Y. (1998) Infect. Immun. 66, 2207-2212). To clarify the antigenically related hemagglutinating domains, we attempted to determine the minimum motifs responsible for P. gingivalis hemagglutinin. Initially, the 9-kilobase EcoRI fragment encoding the 130-kDa protein was cloned from the P. gingivalis chromosome using mAb-Pg-vc. Western blot analysis of nested deletion clones, the competition experiments using synthetic peptides, and the binding assay of the phage-displayed peptides using the mAb-Pg-vc allowed us to identify the minimum motifs, PVQNLT. Furthermore, the presence of multi-gene family coding for this epitope was confirmed via Southern blot analysis and PCR using the primers complementary to the domain corresponding to this epitope. It is suggested that the hemagglutinin-associated motif may be PVQNLT and that the gene families specifying this motif found in P. gingivalis chromosome encode many hemagglutinin and/or hemagglutinin-related proteases.

Adhesins, Bacterial↗

PubMed1999

In situ detection of gelatinolytic activity in developing craniofacial tissues.

Frozen tissue sections of developing and adult rat heads were incubated on a film coated with a gelatin-containing colloidal silver emulsion in order to detect gelatinolytic activity present in the different tissues. The method, termed film in situ zymography, is based on the ability of the thiol group of the propeptide released from the degraded gelatin to induce a structural change in the colloidal silver and thereby a visible change in color. The frozen tissue sections mounted on the coated film were incubated at 37 degrees C overnight. Gelatinolytic activity was detected as a color change from yellow to red. The activity of gelatinase was completely blocked by phenanthroline, which inhibits matrix metalloproteinases. Gelatinolytic activity was widely present in the oral epithelium, tooth buds, tongue, Meckel's cartilage, salivary glands, and other tissues. The intensity of the gelatinolytic activity varied among the different tissue types. The present study demonstrated gelatinolytic activity in both developing and adult craniofacial tissues. These results suggest that gelatinolytic activity plays an important role in normal turn-over in several tissues. Whereas some of the activity also in the developing rats may be related to this turn-over process, some of it is probably directly associated with developmental changes.

Animals↗

PubMed1999

Stimulatory effect of laser irradiation on calcified nodule formation in human dental pulp fibroblasts.

The purpose of the present study was to investigate the effect of laser irradiation on calcified nodule formation in human dental pulp (HDP) cells. HDP cells were irradiated once with a Ga-Al-As laser for 5 and 10 min, and calcified nodule formation was determined by von Kossa staining. The laser irradiation increased the number of calcified nodules in a time-dependent manner. The activity of alkaline phosphatase and production of collagen and osteocalcin in conditioned medium were measured. Both were higher in the irradiated group than in the nonirradiated group. These results suggested that formation of calcified nodules in HDP cells, as well as in alkaline phosphatase activity, the production of collagen and osteocalcin were enhanced by laser irradiation.

Alkaline Phosphatase↗

PubMed1999

Enhancement of lipopolysaccharide-stimulated PGE2 and IL-1beta production in gingival fibroblast cells from old rats.

The effect of aging on gingival fibroblasts in response to bacterial infection was studied. Rat gingival fibroblast (rGF) cells were cultured from gingival tissue removed from young (6 weeks old) and old (20 months old) rats. Both types of rGF cells were challenged with lipopolysaccharide (LPS) from the periodontal pathogen Campylobacter rectus. The levels of prostaglandin E2 (PGE2) and interleukin 1beta (IL-1beta) released into the cultured medium were measured by a specific radioimmunoassay. LPS stimulated PGE2 and IL-1beta production in a dose-and time-dependent manner in rGF cells from both young and old rats was seen. Production of PGE2 and IL-1beta by rGF cells from the old rats was higher than those from the young in response to LPS. This greater ability from the older rGF cells to produce PGE2 and IL-1beta was due to higher mRNA levels of cyclooxygenase 2 and IL-1beta, respectively. In contrast, cyclooxygenase-1 and IL-1beta converting enzyme gene mRNA levels remained unchanged. Because LPS-stimulated PGE2 and IL-1beta production was enhanced by in vivo cellular aging, aging of GF may affect the severity of inflammation and bone resorption by producing a large amount of PGE2 and IL-1beta in response to bacterial infection.

Aged↗

PubMed1999

Enhancement of LPS-stimulated plasminogen activator production in aged gingival fibroblasts.

Plasminogen activator (PA) converts plasminogen to plasmin, and plasmin activates the kinin cascade and latent methalloproteases. It is known that the alteration of the PA-plasmin system affects the progression of periodontal disease. We have reported previously that LPS from Campylobacter rectus, which is associated with adult periodontitis, increased PA production in human gingival fibroblasts (hGF). The effects of in vitro- and in vivo-cellular ageing on PA production from human and rat gingival fibroblasts (rGF) were studied. In vitro cellular aged hGF were prepared by subcultivations of hGF, and in vivo aged rGF was cultured primarily from the gingival tissue of aged rats. The cells were challenged with LPS and PA released into the cultured medium was measured as PA activity. Both in vitro and in vivo cellular aged GFs produced a significantly higher PA activity by LPS compared with young GFs cell. In RT-PCR experiments, tissue type PA (tPA) mRNA levels in both aged hGF and rGF were higher than in young cells, whereas plasminogen activator inhibitor 1 (PAI-1) mRNA remained unchanged and urotype PA (uPA) mRNA was not detected. Since LPS-stimulated PA activity from gingival fibroblasts was stimulated in aged cells using both in vitro- and in vivo-experimental models, the ageing of gingival fibroblasts may have an effect on the severity of inflammation and degradation of the extracellular matrix of gingival tissues by producing a large amount of PA in response to LPS.

Animals↗

PubMed1999

Inhibition of Na+ channel or Na+/H+ exchanger attenuates the hydrogen peroxide-induced derangements in isolated perfused rat heart.

The effect of tetrodotoxin, a specific inhibitor of the Na+ channel, and 5-(N,N-dimethyl)-amiloride, a specific inhibitor of the Na+/H+ exchanger, on the mechanical and metabolic derangements induced by hydrogen peroxide (H2O2) was studied in the isolated perfused rat heart. The isolated rat heart was perfused aerobically at a constant flow rate and driven electrically. H2O2 (600 microM) decreased the left ventricular developed pressure and increased the left ventricular end-diastolic pressure (i.e. mechanical dysfunction), decreased the tissue levels of adenosine triphosphate and adenosine diphosphate (i.e. metabolic derangement), and increased the tissue level of malondialdehyde (i.e. lipid peroxidation). These mechanical and metabolic derangements induced by H2O2 were significantly attenuated by tetrodotoxin (3 microM) or 5-(N,N-dimethyl)-amiloride (15 microM). Neither tetrodotoxin nor 5-(N,N-dimethyl)-amiloride modified the tissue malondialdehyde level, which was increased by H2O2. In the normal (H2O2-untreated) heart, neither tetrodotoxin nor 5-(N,N-dimethyl)-amiloride affected the mechanical function and energy metabolism. These results suggested that inhibition of the Na+ channel or Na+/H+ exchanger was effective in attenuating the H2O2-induced mechanical dysfunction and metabolic derangements in the isolated perfused rat heart.

Amiloride↗

PubMed1999

[Cardiac cell injury induced by lysophosphatidylcholine].

Lysophosphatidylcholine (LPC) is an amphiphilic metabolite produced from membrane-phospholipids by the activation of phospholipase A2 (PLA2), and it accumulates in the ischemic myocardium. It has been demonstrated that exogenous LPC produces an increase in intracellular Ca2+ concentration ([Ca2+]i), morphological change from rod- to round-shape, and increase in release of creatine kinase (CK). The possible mechanism of the Ca2+ overload induced by LPC is direct Ca2+ entry via a nonselective cation channel (or pore) or secondary Ca2+ entry via Na(+)-Ca2+ exchanger after increase in intracellular Na+ concentration. Among anti-ischemic drugs including beta-adrenoceptor antagonists and Ca2+ channel blockers, a drug with high lipophilicity attenuates the LPC-induced cellular damage, probably due to the preservation of membrane integrity. Because LPC, which accumulates during ischemia and reperfusion of the heart, and produces Ca2+ overload, it is possible that LPC potentiates the ischemic injury in the heart. Therefore, development of protective drugs against cell injury induced by LPC would represent a new approach to finding new drugs that protect the heart against ischemic injury.

Animals↗

PubMed1999

Protective effect of quinaprilat, an active metabolite of quinapril, on Ca2+-overload induced by lysophosphatidylcholine in isolated rat cardiomyocytes.

We examined the effects of quinaprilat, an active metabolite of quinapril (an angiotensin converting enzyme (ACE) inhibitor) on the increase in intracellular concentration of Ca2+ ([Ca2+]i) (Ca2+-overload) induced by lysophosphatidylcholine (LPC) in isolated rat cardiomyocytes. LPC (15 microM) produced Ca2+-overload with a change in cell-shape from rod to round. Quinaprilat but not quinapril at 20 or 50 microM attenuated the LPC-induced increase in [Ca2+]i and the change in cell-shape in a concentration-dependent manner. Since quinaprilat has an inhibitory action on ACE and quinapril has practically no inhibitory action on ACE, it is likely that the inhibitory action of quinaprilat on ACE is necessary for the protective effect of the drug against LPC-induced changes. We therefore examined the effects of enalapril (another ACE inhibitor with the weak inhibitory action on ACE) and enalaprilat (an active metabolite of enalapril with an inhibitory action on ACE) on the LPC-induced changes. Both enalapril and enalaprilat attenuated the LPC-induced Ca2+-overload, suggesting that the inhibitory action on ACE may not mainly contribute to the protective effect of ACE inhibitors against LPC-induced Ca2+-overload. This suggestion was supported by the fact that neither ACE (0.2 U/ml) nor angiotensin II (0.1-100 microM) increased [Ca2+]i in isolated cardiomyocytes. Furthermore, application of bradykinin (0.01-10 microM) did not enhance the protective effect of quinaprilat against LPC-induced changes. LPC also increased release of creatine kinase (CK) from the myocyte markedly, and quinaprilat but not quinapril attenuated the LPC-induced CK release. Unexpectedly, both enalapril and enalaprilat did not attenuate the LPC-induced CK release. Neither quinapril nor quinaprilat changed the critical micelle concentration of LPC, suggesting that these drugs do not directly bind to LPC. We conclude that quinaprilat attenuates the LPC-induced increase in [Ca2+]i, and that the protective effect of quinaprilat on the LPC-induced change may not be related to a decrease in angiotensin II production or an increase in bradykinin production.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1999

Antisense oligonucleotide of tissue inhibitor of metalloproteinase-1 induces the plasminogen activator activity in periodontal ligament cells.

BACKGROUND: Matrix metalloproteinases (MMPs), produced by both infiltrating and resident cells of the periodontium, play a role in physiologic and pathologic events. It is recognized that an imbalance between activated MMPs and their endogenous inhibitors leads to pathologic breakdown of the extracellular matrix during periodontitis. Although it is known that pro-MMPs are activated by the plasminogen activator (PA)/plasmin system, and that the activated MMPs are inactivated by tissue inhibitor of metalloproteinases (TIMPs), participation of TIMPs in the PA/plasmin system has not been defined. METHODS: We investigated the effects of the antisense oligonucleotide, consisting of a 21-base sequence from the human TIMP-1 gene including the first ATG initiation codon, on PA/plasmin activities in the cultured medium of periodontal ligament (PDL) fibroblastic cells. Antisense or sense oligonucleotides were directly added into cell-cultured medium, and enzyme activities from the PDL cells were measured. RESULTS: Antisense TIMP-1 oligonucleotide specifically stimulated the PA activity dose-dependently. Other oligonucleotides, sense TIMP-1 or antisense TIMP-2, did not affect PA activity in PDL cells. The PA activity increased by antisense TIMP-1 oligonucleotide was due to an increase of urokinase-type PA (uPA) protein, but not that of tissue-type PA by means of immunoblotting. Furthermore, the stimulation of PA activity in the conditioned medium by adding antisense oligonucleotide for TIMP-1 was not due to the decreasing levels of PA inhibitor-1, an inhibitor of PA. CONCLUSIONS: TIMP-1 controls the synthesis of uPA in the PDL cells. Control of the TIMP-uPA system is important in inflammatory periodontal ligament healing.

Analysis of Variance↗

PubMed1999

Increase of urokinase-type plasminogen activator receptor expression in human gingival fibroblasts by Porphyromonas gingivalis lipopolysaccharide.

BACKGROUND: Urokinase-type plasminogen activator receptor (uPAR) presenting on the cell surface with glycosylphosphatidylinositol (GPI) anchor is a key component in the plasminogen activator (PA)-plasmin system and plays a critical role in extracellular matrix degradation. It is believed that uPAR serves to localize and accelerate this generation system. In this study, we examined the levels of both uPA and uPAR in human gingival fibroblasts treated with Porphyromonas gingivalis lipopolysaccharide (LPS). METHODS: Human gingival fibroblasts from the seventh to tenth doubling passages were plated at 5x10(4) cells per well in 24-well plates. The confluent-stage cells were cultured for 24 hours in alpha-MEM medium containing 2% fetal calf serum, after which they were incubated with P. gingivalis LPS. PA activity was measured using plasminogen and plasmin substrate S2251. RESULTS: PA activity in the cell lysate was increased by LPS and reached maximum at 1 microg/ml LPS after being incubated for 8 hours. PA activity released by phosphatidylinositol-specific phospholipase C, which detaches the GPI anchor, was also increased by LPS. The activity was inhibited by amiloride, which is a specific inhibitor for uPA. LPS increased the protein and mRNA levels of both uPA and uPAR in gingival fibroblasts. CONCLUSIONS: These findings suggest that increase of the uPAR level by LPS may play an important role in the progression of periodontal diseases through pericellular proteolysis.

Cells, Cultured↗

PubMed1999

Opsonophagocytic effect of antibody against recombinant conserved 40-kDa outer membrane protein of Porphyromonas gingivalis.

BACKGROUND: Porphyromonas gingivalis is associated with the initiation and progression of adult periodontitis. The outer membrane proteins of the bacteria are potentially important targets for interaction with host defense systems. A 40-kDa outer membrane protein (40-kDa OMP) is conserved among many strains of P. gingivalis. We have cloned the gene for 40-kDa OMP from P. gingivalis 381 and produced a recombinant protein. For the development of recombinant 40-kDa OMP as a component of a vaccine for passive immunization, the elucidation of the roles of the anti-recombinant 40-kDa OMP antibody in the host defense against P. gingivalis is essential. The objective of this study was to determine the opsonic capacity of the antibody for phagocytosis by neutrophils which play a key role in the immune response to microbial infections. METHODS: To test the opsonic activity of a rabbit polyclonal antibody against r40-kDa OMP (r40-kDa OMP Ab) on human neutrophils to phagocytize P. gingivalis, we constructed a reproducible in vitro model of P. gingivalis-neutrophil interaction using the human promyelocytic cell line HL-60. RESULTS: We demonstrated that r40-kDa OMP Ab in the presence of human complement successfully opsonized [3H]-thymidine-labeled P. gingivalis as a target for phagocytosis by HL-60 cells differentiated with dimethyl sulfoxide. The phagocytized bacteria were then intracellularly killed and lysed, and the radioactive degradation debris egested into the culture medium. CONCLUSIONS: We conclude that antibody against r40-kDa OMP has opsonic activity on human neutrophil function for phagocytosis of P. gingivalis. Subgingival bacteria are coated in vivo with immunoglobulin and complement. When the antibody is specific for crevicular bacteria, immunological interactions can be expected in the crevice. Our observations suggest that the anti-recombinant 40-kDa OMP antibody in concert with the crevicular complement may prevent P. gingivalis colonization r40-kDa OMP may contribute to the development of a local immunotherapy when applied to the crevice of a patient with P. gingivalis-related periodontitis which relates to susceptibility for certain systemic diseases such as diabetes mellitus, cardiovascular disease, and preterm labor.

Animals↗

PubMed1998

Sequence analysis of the Porphyromonas gingivalis dipeptidyl peptidase IV gene.

We previously constructed a Porphyromonas gingivalis genomic library and isolated the 2.9 kb EcoRV fragment which specified glycylprolyl dipeptidyl aminopeptidase (GPase). Nucleotide sequencing of this fragment identified the single 2169 bp open reading frame which coded for a 723 amino acid protein. The amino acid sequencing of the NH2-terminal domain of the native and recombinant mature enzymes suggested that the protease possessed a 16 amino acid residue signal peptide. The calculated mass of the precursor and mature proteases were 82,018 and 80,235 daltons, respectively. The homology search of this enzyme in registered protein sequences revealed that this enzyme was homologous to dipeptidyl peptidase (DPP) IV from the Flavobacterium meningosepticum and that from eukaryotic cells, including the human, mouse, and rat. Three amino acid residues, Ser-593, Asp-668, and His-700, were identified as a putative catalytic triad, a common feature of eukaryotic serine proteases. In addition, this enzyme showed a broad proteolytic spectrum toward synthetic substrates capable of splitting not only Gly-Pro-derivative but also Ala-Pro, Lys-Pro, and Phe-Pro-derivatives. Therefore, we conclude that this enzyme belongs to DPP IV rather than GPase.

Amino Acid Sequence↗