Autoepitopes of the 52-kd SS-A/Ro molecule

OBJECTIVE

This study was undertaken to clarify the mechanisms responsible for the generation of anti-52-kd SS-A/Ro autoantibodies and to elucidate why, as has recently been reported, anti-52-kd autoantibodies preferentially recognize the denatured form rather than the native 52-kd molecule.

METHODS

Using a series of truncated 52-kd autoantigens, produced as beta-galactosidase fusion proteins in Escherichia coli, the B cell epitope distribution was probed with 18 anti-Ro-positive sera by immunoblotting and by enzyme-linked immunosorbent assay.

RESULTS

Nearly all the antigenicity of the molecule was found to be linked to its leucine zipper region. In a further study using 9 of the 18 sera, the antigenicity of the molecule was found to be mainly formed by multiple conformational epitopes, and one of these epitopes appeared to be universally recognized by all the sera tested.

CONCLUSION

The recognition of multiple epitopes indicates that the Ro 52-kd antigen itself drives the autoimmunity to this molecule. Further, the concentration of the antigenicity at the leucine zipper region may explain why anti-52-kd antibodies preferentially recognize the denatured protein rather than its native form.

A comparison of the surgical results in patients with hepatitis B versus hepatitis C-related hepatocellular carcinoma

To assess the differences in the surgical results between patients with hepatitis B- and hepatitis C-related hepatocellular carcinoma (HCC), the operative outcomes of 30 patients with hepatitis B surface antigen (HBsAg)-positive (the B-HCC group) and 96 patients with hepatitis C antibody (HCVAb)-positive (the C-HCC group), who had undergone hepatic resection from 1989 to 1993, were compared. The mean age of the patients in the C-HCC group was higher than that in the B-HCC group (61.7 years vs. 57.0 years, P < .05). The C-HCC group demonstrated both a greater decrease in liver function and a larger enhancement of inflammatory changes in the liver under a pathological examination (the current rate of active hepatitis: 69% vs. 27%, P < .001). There was also a higher incidence of total postoperative complications in the C-HCC group (60% vs. 37%, P < .05); however, regarding each individual complication, the rate was similar between the two groups. Two of the six patients with postoperative hepatic failure in the C-HCC group died. The mortality rate in the C-HCC group was 2%, but no operative death was encountered in the B-HCC group. The crude survival and the disease-free survival rates at 5 years were similar, 61.8% and 46.2% in the B-HCC group and 52.8% and 23.2% in the C-HCC group, respectively. The patterns of recurrence were also similar in both groups. The pathological features of HCC were similar between the two groups. In conclusion, the surgical results between the two groups were almost identical.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of integrins involved in cell adhesion to native and denatured type I collagens and the phenotypic transition of rabbit arterial smooth muscle cells

Rabbit smooth muscle cells (SMC) in primary culture attached to and started proliferating on native and heat-denatured type I collagens, although the amount of cell attachment to denatured collagen was significantly lower. The cells adhered poorly and were unable to grow on commercial gelatin. In contrast, synthetic SMC in secondary culture could adhere to gelatin and grew as well on gelatin as on native type I collagen. The SMC in the contractile state adhered to native type I collagen through the alpha 1 beta 1 and alpha 3 beta 1 integrins. The cells in the intermediate phenotype also adhered to the substrate through the alpha 1 beta 1 and alpha 3 beta 1 integrins, but the relative amount of alpha 3 integrin decreased. The initial adhesion of cells in secondary culture to native type I collagen was mediated only by the alpha 1 beta 1 integrin. The cell-binding sequences did not contain DGEA (Asp-Gly-Glu-Ala) or RGD (Arg-Gly-Asp). In contrast, cell adhesion to heat-denatured type I collagen was mediated only by the alpha 1 beta 1 integrin in the contractile state and by the alpha 1 beta 1, alpha 2 beta 1, and alpha 3 beta 1 integrins in the synthetic state. In heat-denatured type I collagen, the sequences DGEA and RGD served as a recognition site for the alpha 2 beta 1 and alpha 3 beta 1 integrins. Our results suggest that rabbit SMC can recognize the native and denatured type I collagens through interactions with the triple helix-binding receptors and alpha chain-binding receptors and that the expression pattern of integrins changes in conjunction with the phenotypic properties of vascular SMC.

[Homicide by strangulation with a lasso sling]

A 50-year-old physically handicapped man was found dead on his wheelchair in a short passage on the ground floor of a high-rise housing development. The lattice doors at the both ends of the passage were closed and the wheelchair with the body was found at the door to an adjoining indoor parking place for bicycles. A noose of a vinyl plastic cord was found wound around the neck; the other end of the cord was tied through the lattice door to a handrail on the wall of the parking place. The wheelchair was stopped sideways; its chair back was in contact with a doorpost. The body which was slipped from the seat of the wheelchair was incompletely suspended by the noose. The cause of death primarily was diagnosed as hanging. The police suspected murder and arrested a 21-year-old male assailant. According to his confession, the assailant pushed the wheelchair through the lattice door in the passage, stopped it at the door and braked it. Immediately thereafter he returned to the parking place and locked the lattice door behind him. After having made a kind of lasso using a cord taken off from a bicycle which has been sitting there, he reached out his hands through the lattice door and lassoed the man on the wheelchair from behind. Finally, he tied another end of the lasso to the handrail. It was considered that the body of the victim was slipped down in the stage of convulsion and incompletely suspended by the noose.

[A case of solitary tuberculosis in lower lung field showing marked pleural indentation complicated with chronic renal failure with special reference to mechanism of of formation of pleural retraction]

A case of 62-year-old male patient with tuberculosis in the lower lung field of right side was reported. The case showed a solitary lesion in S8b of 2.5 x 2.0 cm in size and was detected by the mass survey. The case was complicated with chronic renal failure and was treated by lobectomy because of suspicion of lung cancer, as there was a marked pleural indentation on CT. By examining the resected specimen, the following findings were revealed. The solitary exudative tuberculous lesion located in the margin of the basal segment extended both to the costal and diaphragmatic pleura, and a small triangular shaped normal lung parenchyma located at the periphery of the lesion was isolated, and the air flow from the lower lobar bronchus was cut. As a result, hyperinflation of the isolated normal lung took place through collateral air leak and check-valve mechanism (The Culiner Theory), finally the pleural constriction was formed at the boundary between the lesion where the elasticity was lost and the hyperinflated parenchyma.

Effects of fluvastatin, a new inhibitor of HMG-CoA reductase, and niceritrol on serum lipids, lipoproteins and cholesterol ester transfer activity in primary hypercholesterolemic patients

Effects of a combination therapy of fluvastatin, a new inhibitor of HMG-CoA reductase, and niceritrol on lipid metabolism were investigated measuring a wide range of parameters in 42 patients with primary hypercholesterolemia. After a wash-out period patients were randomly allocated to 1 of the 2 groups, the fluvastatin-preceding group (G-1) and the niceritrol-preceding group (G-2). In G-1 fluvastatin monotherapy (30 mg/day) significantly decreased total cholesterol (TC) and LDL-cholesterol (LDL-C). There was no significant change in HDL-cholesterol (HDL-C), triglyceride (TG) and lipoprotein (a) (Lp(a)). Further effect in HDL-C and TG was observed after the addition of niceritrol (750 mg/day). On the other hand, in G-2, while niceritrol alone (750 mg/day) produced no significant change in TC, LDL-C, HDL-C, TG and Lp(a), the addition of fluvastatin (30 mg/day) reduced TC and LDL-C levels significantly. Cholesterol ester transfer (CET) activity was significantly reduced by niceritrol monotherapy. After the concomitant use of the 2 drugs CET activity was significantly reduced only in G-2. No significant change in lipoprotein lipase and hepatic triglyceride lipase activities were observed in the 2 groups at either point in time. No serious adverse effect was observed in this study. It is concluded that fluvastatin is an effective drug for lowering LDL-cholesterol and causes no adverse alteration in lipid metabolism. Combination with niceritrol at a dose of 750 mg/day dose not appear to augment or attenuate beneficial effects of fluvastatin.

Cloning of the creatinine amidohydrolase gene from Pseudomonas sp. PS-7

The gene encoding creatinine amidohydrolase (EC 3.5.2.10) was isolated from Pseudomonas sp. PS-7. The primary structure of creatinine amidohydrolase deduced from the nucleotide sequence showed that the protein is composed of 259 amino acids and has a molecular weight of 28,437. The enzymatic property of creatinine amidohydrolase produced by recombinant E. coli was identical with those by Pseudomonas sp. PS-7.

Anterior mediastinal schwannoma: a case report

The most common neoplasms of the mediastinum are those of neurogenic origin, and the majority of these arise in the posterior compartment. We report a case of benign schwannoma originating in rare location, the anterior mediastinum, and its imaging findings.

Development and application of a homologous radioimmunoassay for Xenopus prolactin

A specific and sensitive homologous radioimmunoassay (RIA) for Xenopus prolactin (xPRL) was developed. PRL isolated from X. laevis pituitary glands was used for generating antiserum in a rabbit, for radioligand and for the standard. Pituitary homogenates and plasma from adult Xenopus produced displacement curves parallel to the xPRL standard. Plasma from hypophysectomized Xenopus showed negligible cross-reactivity. Purified PRLs from other amphibian species such as the bullfrog (Rana catesbeiana) and toad (Bufo japonicus) gave inhibition curves which did not parallel the standard. Ovine PRL, mouse PRL, newt (Cynops pyrrhogaster) PRL, bullfrog GH, and bullfrog LH showed no inhibition of binding even at relatively high doses in this RIA. The sensitivity of the RIA was 0.122 +/- 0.005 ng xPRL/100 microliters assay buffer. Intraassay and interassay coefficients of variation were 2.46 and 6.65%, respectively. Histological studies of Xenopus adenohypophyses revealed that the cells which reacted immunologically with the antiserum against xPRL corresponded to those positively stained with antiserum against bullfrog PRL. A preliminary application of this homologous RIA for xPRL was performed by evaluating plasma and pituitary PRL levels in subadult and adult Xenopus of both sexes.

Comparative pharmacokinetic/pharmacodynamic study of proton pump inhibitors, omeprazole and lansoprazole in rats

The relationship between plasma concentrations and inhibitory effects on gastric acid secretion by omeprazole (OPZ) and lansoprazole (LPZ), which are used as antiulcer drugs in the clinical stage, was analyzed using the pharmacokinetic/pharmacodynamic (PK/PD) model in rats. After intravenous administration of OPZ and LPZ (1 mg/kg), OPZ was eliminated 1-exponentially and LPZ was eliminated 2-exponentially from plasma. Elimination was rapid with total body clearance of 57.6 ml/min/kg for OPZ and 58.6 ml/min/kg for LPZ. The volumes of distribution at steady-state were 0.66 liter/kg for OPZ and 1.04 liter/kg for LPZ, and the plasma unbound fractions were 0.105 and 0.069. The dose at which 50% of the maximum effect is elicited for the suppression of gastric acid secretion stimulated by histamine was 0.28 +/- 0.13 mg/kg (estimated value +/- SD) for OPZ and 0.18 +/- 0.03 mg/kg for LPZ. Second-order rate constants for association of OPZ or LPZ and H+,K+-ATPase based on a PK/PD model were 72.5 +/- 30.0 (estimated value +/- SD) and 124 +/- 58 ml/micrograms/hr respectively. Apparent turnover rate of H+,K+-ATPase was 8.8 hr as half-life, assuming the same value for both drugs. We concluded that pharmacokinetic elimination patterns of OPZ and LPZ were different, whereas the pharmacodynamic characteristics of both drugs are nearly the same in rats.

Overexpression of human lipoprotein lipase increases hormone-sensitive lipase activity in adipose tissue of mice

An elevation of lipoprotein lipase (LPL) activity in adipose tissue is considered a possible cause of obesity. However, transgenic mice that overexpress the human LPL gene showed no increase in fat deposition as compared with controls. In the present study, we investigated effects of LPL on fat accumulation. Respiratory quotients and uptake of [3H] triolein by tissues (white and brown adipose tissue, and skeletal muscles) did not differ significantly for transgenic and non-transgenic mice. The mRNA levels of hormone-sensitive lipase (HSL) and HSL activity in adipose tissue during feeding were higher in LPL transgenic mice than in controls. Results suggest that the overexpression of LPL does not induce obesity by enhancing the hydrolysis of triglycerides in adipose tissue.

A protein kinase C with divalent cations contributes to thromboxane A2-induced contraction in rabbit vascular smooth muscle

We investigated the mechanism of contraction induced by a stable thromboxane A2 receptor agonist, STA2, in rabbit aortic smooth muscles. STA2 induced a long-lasting contraction which persisted for over 5 hours. This contraction was found to be potently inhibited by EDTA. In the presence of EGTA, STA2 was able to slowly contract muscle to a near maximum level, suggestive of an extracellular Ca(2+)-independent component in STA2 action. Inhibition of the STA2-induced contraction by EDTA was partially overcome by the addition of Mg2+. Ca2+ and Mn2+ were also effective in attenuating the inhibition. A phorbol ester, PDBu, an activator of PKC (protein kinase C), induced a long lasting contraction in a manner similar to that of STA2. PKC inhibitors, staurosporine and H-7, inhibited the lasting contractions induced by STA2 and PDBu. PKC inhibitors abolished STA(2)-induced contraction in the absence of extracellular Ca2+, suggesting that Ca(2+)-influx from the extracellular space as well as PKC activation are involved in STA(2)-induced contraction. ML-7, a myosin light chain kinase inhibitor, also inhibited the STA(2)-induced contraction, but it did not abolish the contraction in the absence of extracellular Ca2+. Furthermore, STA2 elicited phosphatidylcholine hydrolysis in cultured aortic smooth muscle cells. From the results obtained, we arrived at the hypothesis that PKC contributes to this lasting contraction in the presence of divalent cations, such as Mg2+, Ca2+ or Mn2+. Of these, Mg2+ is the most capable of maintaining this contraction. The Ca-dependent process alone could not account for the long lasting contraction induced by STA2 in vascular smooth muscles.

A possible involvement of sodium channel blockade of class-I-type antiarrhythmic agents in postischemic contractile recovery of isolated, perfused hearts

The present study was undertaken to test the hypothesis that the degree of sodium channel blockade by class-I-type antiarrhythmic agents accounts for enhancement of postischemic contractile recovery of ischemic/reperfused hearts. Electrophysiological studies showed that the class-I-type antiarrhythmic agents quinidine, disopyramide, procainamide, lidocaine, mexiletine, flecainide and pilsicainide suppressed the Vmax value of the rat left ventricular muscle cell, a marker of sodium channel blockade, in a concentration-dependent manner. Isolated rat hearts were subjected to 35 min of ischemia and 60 min of reperfusion. Postischemic contractile recovery, which was never detected in untreated hearts, was enhanced in hearts pretreated with these antiarrhythmic agents during the last 3 min before ischemia at concentrations ranging from 3 to 300 microM. Tissue Na, but not Ca, accumulation was also detected in the ischemic heart, and tissue Na and Ca accumulation was observed in the reperfused heart, which suggests that sodium overload occurs during ischemia, followed by sodium and calcium overload during reperfusion. The degree of postischemic contractile recovery seen in the presence of these antiarrhythmic agents was inversely related to tissue Na or Ca accumulation after reperfusion, which suggests that class-I-type antiarrhythmic agents inhibit sodium overload occurring in ischemic/reperfused myocardial cells. A close relationship between postischemic contractile recovery of the perfused heart and depression in the Vmax value of the ventricular muscle was also observed. These results suggest that the ability class-I-type antiarrhythmic agents to inhibit myocardial sodium channels plays a significant role in the enhancement of postischemic contractile recovery of the ischemic/reperfused heart.

Age-related differential mRNA expression of T cell cytokines in NZB/NZW F1 mice

The mRNA expression of interleukin (IL)-2, IL-2 receptor-alpha-chain (IL-2R alpha), IL-4 and interferon-gamma (IFN-gamma) in spleen cells from NZB/NZW F1) mice following the stimulation with concanavalin A (Con A) was examined by Northern blot analysis. Kinetic patterns of the mRNA expression after the stimulation were not different between 2-month-old and 6 to 8-month-old B/W F1 mice. However, relative mRNA expression of IL-2 to a cytoskeletal protein, alpha-Tubulin was lower in 6 to 8-month-old B/W F1 mice than in 2-month-old mice. Similar but not significant tendency was observed in IL-2R mRNA expression. In contrast, Relative IL-4 mRNA expression in 6 to 8-month-old B/W F1 mice was significantly higher than that in 2-month-old animals. On the other hand, no apparent change was observed in IFN-gamma mRNA expression. Flow cytometric analysis indicated that there was no apparent difference in proportion of L3T4 positive T cells in spleen cells from 2 and 6 to 8-month-old B/W F1 mice. These results suggest that mRNA expression of IL-2 and IL-4 differentially changes with aging in autoimmune B/W F1 mice.

Dependence of frequency of homologous recombination on the homology length

The frequency of homologous recombination is believed to be a linear function of the length (N bp) of homology between DNAs. Here, the N intercept is believed to be determined by a threshold length below which some physical constraint is effective. In the mammalian gene targeting systems, however, the frequency depends more steeply than linearly on the homology length. To explain both the linear dependence and the steeper dependence, we propose a model where the branch point of a reaction intermediate is assumed to "walk randomly" along the homologous region until it is processed. The intermediate is assumed to be destroyed if the branch point ever reaches either end of the homology. In this model, the length dependence is governed by a parameter, h, which is defined as efficiency of processing of the intermediate and reflects unlikelihood of the destruction at either end of the homology. We find that the frequency is proportional to N3 for smaller N and is a linear function of N for larger N. Where the shift from the N3 dependence to the linear dependence takes place is determined by the parameter h. The range of N showing the N3 dependence becomes narrower as h becomes larger. The dependence steeper than linear dependence, which is observed not only in the mammalian gene targeting system but also in bacteriophage T4, Escherichia coli and yeast systems, agrees well with the predicted N3 dependence. The N intercept is determined not by physical (or structural) constraints but only by the parameter h in this model.

A case report of synovial sarcoma with translocation (X;18). Application of fluorescence in situ hybridization to paraffin-embedded tissue

A 57-year-old female patient with synovial sarcoma in her right foot had a chromosome abnormality defined as translocation (X;18). The tumour was located in the subcutis, and histological investigation showed monophasic proliferation of oval to spindle-shaped cells with a fascicular arrangement lacking an epithelial component. Immunostaining disclosed no cytokeratin or epithelial membrane antigen in tumour cells. Karyotypic analysis revealed translocation (X;18) in addition to other nonspecific aberrations. Fluorescence in situ hybridization was carried out on paraffin-embedded tissue, using DNA probes for the centromeres of chromosomes X and 18 with whole chromosome painting probes for X and 18. The free nuclei showed two signals at a rate of 83-85% with the X and 18 centromeric probes, in contrast to three signals at a rate of 68-70% with the X and 18 painting probes.

[A case of arteriovenous malformation successfully treated with functional mapping of the language area by PET activation study]

The authors report a case of temporal AVM safely treated by mapping the language area with PET activation study. The patient was a 50-year-old woman with temporal epilepsy as her chief complaint. MRI and angiography revealed a right temporal AVM. Before surgical treatment, we assessed the dominant hemisphere with PET activation study. We performed PET scanning while the patient was playing "capping" (called "Shiritori" in Japanese), from which we subtracted PET images performed when she was in a resting state, and then we superimposed those images upon MRIs. The blood flow increased in the left frontal operculum (Broca's area), the left caudal head, the left putamen and the right cerebellar hemisphere. We were thus able to determine that her left hemisphere was dominant, and that it was safe to undertake embolization and operation for the AVM. Postoperative course was uneventful and higher cortical functions were preserved perfectly. In cases of cerebral AVMs, unusual dominancy of cerebral hemispheres is often encountered, and so, preoperative evaluation of the relation of AVM to the eloquent cortex is essential. In our study, blood flow increased in some areas other than the language area, but they were considered to be areas related to phonation, and we think that we were able to map the language area. Though this method is still in its preliminary stage, we think it gives us useful information for surgical treatment of cerebral AVMs.

Molecular epidemiology of Vibrio cholerae O1 isolated in Nepal by southern hybridization with a cholera toxin gene probe

A cholera epidemic broke out in 1992 due to Vibrio cholerae O1 biotype El Tor in the eastern and southern belt of Nepal mainly among the Bhutanese refugees. Restriction fragment profiles (RFP) of DNA fragments of V. cholerae O1 isolates hybridized with an enzyme-labelled oligonucleotide probe for cholera toxin gene (ctx) by Southern Hybridization were compared. The probe hybridized with the 13- and 8-kb fragments of PstI-digested total DNA in all isolates observed in the epidemic. This RFP in the Nepalese strain was not observed in the strains isolated during other epidemics but was observed in the strains isolated from the exported marine products from Taiwan and Thailand.

Effects of metamfetamine on auditory P3 component of event-related potentials in rats

Three rats were trained with an oddball paradigm, in which 5 kHz frequent and 10 kHz target rare tones were presented with a probability of 0.8 and 0.2. Pressing the lever within 2 s following the onset of the target tones was rewarded with a drop of food paste. Long latency event-related potentials (ERPs) corresponding to those in humans could be recorded in rats. After the administration of metamfetamine (0.2 mg/kg), the amplitude of surface and intracortical N1 increased, indicating an augmentation of the primary cortical response. Surface P3 showed a decrease of amplitude, accompanied by an increase of intracortical negativity. These alterations of ERPs may be caused by the dysregulation of central noradrenergic system.

Using biopsy materials to detect mutations in gastrointestinal tumors

Because endoscopic examinations are a crucial first step in the diagnosis of carcinomas, we have analyzed point mutations of the c-K-ras and p53 genes using biopsied samples. There is no previous report of such an approach, using only biopsied materials. We analyzed point mutations of the c-K-ras and p53 genes using 60 colorectal and 31 gastric tumor biopsy specimens. None of the gastric and seven of the colorectal tumors had mutations of the c-K-ras gene. p53 gene mutations were detected in six gastric carcinomas [two out of 11 intramucosal carcinomas (18.2%) and four out of 11 invasive carcinomas (36.4%)]. Eight of 15 invasive colorectal carcinomas (53.3%) showed point mutations in the p53 gene. Although point mutation frequencies in this study were relatively low when compared with previous reports in which surgical samples were used, our study shows that biopsied specimens are adequate and useful for analysis of gene point mutations.

Increase of plasma sialic acid upon UV-B irradiation in mouse

In many inflammatory conditions including burns, the plasma sialic acid level rises as an acute responder. Sunburn is a kind of burn. In this study, sunburn was experimentally caused in mice by UV-B irradiation and their plasma sialic acid levels were measured. The levels increased, and reached the maximum 3 d after irradiation. This level was maintained for about 2 d, then it returned to normal within about one week. The increase in the level correlated with the UV dose and the severity of inflammation resulting in sunburn. This assay system was applied to assess the virtue of UV-cut cream in experimental sunburn.

Des-gamma-carboxy prothrombin and proliferative activity of hepatocellular carcinoma

BACKGROUND

Des-gamma-carboxy prothrombin (DCP) is a useful marker for the prognosis of hepatocellular carcinoma (HCC). In this report we investigated the relationship between the positivity of DCP and proliferative activity of HCC and discuss the cause of poor prognosis of DCP-positive HCC.

METHODS

Immunohistochemical and clinicopathologic study was done in 114 patients with resected HCC measuring less than 6 cm in diameter by using monoclonal antibody for proliferating cell nuclear antigen (PCNA).

RESULTS

PCNA labeling index (PCNA-LI) was significantly higher in the patients with DCP-positive HCC than in those with DCP-negative HCC; also a positive correlation was noted between the PCNA-LI and the DCP level. We divided patients into two groups according to the PCNA-LI. In the high PCNA-LI group the patients with DCP-positive HCC exhibited a higher PCNA-LI than did the patients with DCP-negative HCC. As for pathologic prognostic factors, the DCP-positive high PCNA-LI group showed the highest incidence of tumor thrombus of the portal vein and intrahepatic metastasis while also exhibiting the lowest recurrence-freedom rate. From multivariate analysis we find that DCP, as well as PCNA-LI, is one of the risk factors for recurrence of HCC after hepatectomy.

CONCLUSIONS

Our results thus suggest that DCP-positive HCC showed high PCNA-LI, and this might be the main cause for early intrahepatic spread and poor prognosis of DCP-positive HCC.

Effects of size of carbohydrate chain on protease digestion of Aspergillus niger endo-beta-1,4-glucanase

Three different carbohydrate-depleted enzymes were prepared from an endo-beta-1,4-glucanase of Aspergillus niger IFO31125 by treatment with endo-beta-N-acetylglucosaminidase or alpha-mannosidase. They were purified by Concanavalin A-Sepharose affinity and DEAE ion-exchange column chromatographies. The molecular sizes of these enzymes had been decreased from 40 kDa containing 9.0% carbohydrate to 39, 38, and 37 kDa with carbohydrate at 4.5, 1.3, and 0.8% (wt/wt), respectively. The native and these carbohydrate-depleted enzymes were compared in their enzymatic properties, and it was found that they were identical in their catalytic activities and both thermal and pH stabilities. However, the 37-kDa enzyme was more susceptible to proteolysis by Savinase, proteinase K, and Pronase E. On the other hand, the specific protease trypsin showed no such effect on activity of all enzymes. These results suggested that the core structure of the asparagine-linked sugar chain, which consisted of three monosaccharide residues, contributed to the high stability of the endo-beta-1,4-glucanase against protease digestion.