Cloning and sequence analysis of a Bothrops jararaca cDNA encoding a precursor of seven bradykinin-potentiating peptides and a C-type natriuretic peptide

A 1.8-kb cDNA clone was isolated from a Bothrops jararaca venom gland cDNA library that encodes a 256-aa precursor for bradykinin-potentiating peptides (angiotensin-converting enzyme inhibitors) and a C-type natriuretic peptide (CNP). The seven bradykinin-potentiating peptides are aligned tandemly after the hydrophobic signal peptide sequence, followed by a putative intervening sequence and a CNP at the C terminus. Northern blot analysis indicated the predominant expression of a 1.8-kb mRNA in the venom glands as well as in the spleen and the brain. Two lower intensity mRNA bands of 3.5 kb and 5.7 kb also hybridized to the cDNA clone. Radioimmunoassay for the CNP was performed using the antiserum against rat CNP. The presence of CNP immunoreactivity was detected in the low molecular weight fraction of the Bothrops jararaca venom.

Distribution of serotonin-immunoreactive nerve cells and fibers in the rat gastrointestinal tract

The distribution of serotonin-immunoreactive (5HT-IR) nerve cells and fibers was thoroughly investigated immunohistochemically in the rat stomach, duodenum, jejunum, ileum, and colon. The immunoreactivity of the 5HT neurons was compared between non-treated controls and animals treated with colchicine, colchicine plus 5-hydroxytryptophan (5HTP), colchicine plus pargyline, and reserpine. The intensity of immunoreactivity in nerve fibers as well as nerve cell bodies was enhanced mostly in colchicine plus pargyline treated animals, therefore these animals were used for an observation of precise localization of 5HT in the rat gastrointestinal (GI) tract. Immunoreactivity in the nerve cell bodies and fibers was completely abolished in the GI tract of reserpine treated animals. The pattern of localization and projection of 5HT-IR neurons was similar in all segments of the rat GI tract: 5HT-IR nerve cell bodies were located in the myenteric plexus and showed the distinctive features of Dogiel type I neurons. Prominent bundles of varicose fibers traversed the myenteric ganglia and some of them surrounded the cell bodies of immunopositive and immunonegative neurons. 5HT-IR nerve fibers were located in the submucous plexus, densely entwined about the submucosal blood vessels. Most characteristically, 5HT-IR nerve fibers invaded the lamina propria of mucosa where they underlay the crypt epithelium. In conclusion, the present study showed that 5HT-IR neurons located in the myenteric plexus projected fibers widely in the rat GI tract. The localization of fibers in the lamina propria of mucosa implies that this neuron may exert an important role in the epithelial function of the GI tract.

[Chronic myelogenous leukemia expressing two bcr-abl chimeric mRNA; a case report]

Chronic myelogenous leukemia (CML) expresses two types of bcr-abl chimeric mRNA. One is b3a2 type in which bcr exon 3 binds to abl exon 2, the other is b2a2 type that bcr exon 2 binds to abl exon 2. Either bcr-abl is normally expressed, but both types of bcr-abl mRNA can be expressed at the same time in a patient. We report here a rare case of CML expressing two types of bcr-abl mRNA and discuss the possibility that this double expression would help to monitor the clinical course of CML.

[A case of infected subdural hematoma complicating chronic subdural hematoma in a healthy adult man]

The authors report a case of so-called "infected subdural hematoma" as a complication of chronic subdural hematoma. The patient was a 55-year-old man who had sustained a small laceration of the forehead in a traffic accident on March 29, 1995. No fractures were detected on skull roentgenograms, and general and neurological examinations failed to reveal any abnormal findings. In early August 1995, the patient began to experience headaches, and on August 5 he developed a fever of 38 degrees C. On August 8 he suffered a left motor seizure and was admitted to our hospital. Laboratory studies revealed a peripheral leukocyte count of 10,800/mm3 and a C-reactive protein level of 18.1 mg/dl. Computed tomography scans showed a thick right fronto-parietal subdural low density mass and a thin left frontal subdural low density mass. An emergency operation was performed via a single right fronto-parietal burr hole. A chronic subdural hematoma containing slightly yellowish, bloody, purulent fluid was found beneath an outer membrane. The hematoma was irrigated with physiological saline containing antibiotics, and a drain was inserted into the subdural space. A subdural membrane was also present on the left but it contained no pus. Aggressive antibiotic therapy was performed, and the patient was discharged without any neurological deficit. Histologically the membrane was determined to be the outer membrane of a typical chronic subdural hematoma. Enterococcus faecalis, which has rarely been reported to cause infection of the central nervous system, was detected in a bacterial culture of the pus. Systemic investigation showed no evidence of otorhinologic or other focal infection. The above clinical findings suggested that hematogenous seeding of a chronic subdural hematoma had occurred in this patient. Subdural empyema arising from hematogenous seeding to a pre-existing subdural hematoma by an infection is very rare, but this type of complication must be kept in mind not only in the elderly, infants, and compromised hosts, but in patients without complications as well.

Pharmacokinetics of KRM-1648, a new benzoxazinorifamycin, in rats and dogs

The pharmacokinetics of 3'-hydroxy-5'-(4-isobutyl-1-piperazinyl) benzoxazinorifamycin (KRM-1648) in rats and dogs given a single oral dose of 3, 30, or 100 mg/kg of body weight were studied. In the rats, the concentrations of KRM-1648 in plasma, whole blood, and tissues peaked between 2.0 and 24.0 h, with elimination half-lives ranging from 6.2 to 19.5 h. The peak concentrations and the areas under the concentration-versus-time curves (AUC) for whole blood and tissues were 2 to 277 times higher than those for plasma. The high levels of KRM-1648 in tissues were consistent with its large volume of distribution (in excess of 10 liters/kg). A nonlinear increase in peak concentrations and AUCs for plasma, whole blood, and tissues occurred as the dose was increased and was consistent with the dose-dependent decrease in bioavailability. In the dogs, KRM-1648 levels in plasma and whole blood also exhibited a late time to the peak concentration (ranging from 4.0 to 11.2 h), a long elimination half-life (ranging from 15.2 to 24.0 h), and nonlinear kinetics. KRM-1648 exhibited high levels of plasma protein binding (more than 99%) and a high degree of affinity for lipoproteins in the plasma of both animals. After administration of KRM-1648, measurable levels of its metabolites, 25-deacetyl KRM-1648 in rats and 25-deacetyl KRM-1648 and 30-hydroxy KRM-1648 in dogs, were found in the biological samples tested. Thus, KRM-1648 is characterized by a high tissue affinity, a long elimination half-life, and nonlinear pharmacokinetics.

Proliferation marker MIB-1 correlates well with proliferative activity evaluated by BrdU in breast cancer: an immunohistochemical study including correlation with PCNA, p53, c-erbB-2 and estrogen receptor status

The proliferative activity of 30 cases of non-treated invasive ductal breast carcinoma was evaluated by bromodeoxyuridine (BrdU), proliferation marker (MIB-1) and proliferating cell nuclear antigen (PCNA), and the relation between these proliferation markers and histological subtype and histological grade were investigated. In addition, the association of these proliferation markers with overexpression of p53 protein, c-erbB-2 oncoprotein, estrogen receptor (ER) status and clinicopathologic findings were also examined. The BrdU labeling index (LI), MIB-1 score and PCNA labeling rate (LR) correlated with the histological grade. However, there was no statistical difference in proliferative activity among the histological subtypes. A linear strong correlation was demonstrated between BrdU LI and MIB-1 score (r = 0.732). Significant correlation was also found between BrdU LI and PCNA LR (r = 0.446); however, the relation between MIB-1 score and PCNA LR was weak. BrdU LI and MIB-1 score correlated positively with tumor size, TNM stage and overexpression of p53, and negatively with the presence of ER. PCNA LR correlated only with p53. These results indicate that MIB-1 is closely associated with BrdU in clinicopathologic findings and is a more useful tool for evaluating cell proliferation than PCNA. However, it will be necessary to consider the clinical significance of MIB-1 immunohistochemistry cautiously until further widespread clinical and pathological studies are performed.

[LGL lymphoma]

We reported in this article two patients with large granular lymphocytic lymphoma (abbreviated as LGL lymphoma). One was the patient with LGL leukemia/lymphoma (patient 1) and other was the patient with NK-LGL lymphoma (patient 2). Because the gene of TCR delta was rearranged in the patient 1, the clonality of the LGL leukemia/lymphoma was confirmed. However, it is not determined yet whether the lineage of tumor cells is T cells or NK cells. The cytochemical features of the lymphoma cells of the patient 2 were studied. It was found that NK cell-derived lymphoma cells of the patient were positively stained with these two monoclonal antibodies that are reactive with T cell; one is anti-CD45RO (UCHL-1) and other is anti-CD3. Judging from the result, malignant NK-LGL cells in some patients are cytoplasmic CD3+ and UCHl-1+. It is emphasized that May-Grünwald-Giemsa stain of biopsied specimen of the lymphoma is required for making the diagnosis of LGL lymphoma.

Differences in the influence of AIN-purified and non-purified diets on the development of hypertension in SHR and DOCA-salt hypertensive rats

The influence of non-purified and AIN purified diets on the development of hypertension was examined in deoxycorticosterone acetate (DOCA)-salt hypertensive rats and SHRs. For DOCA-salt hypertensive rats, the development of hypertension was slower in rats fed the AIN 76-purified diet than in those fed the non-purified diet throughout the experimental period of about five weeks. In an experiment using spontaneously hypertensive rats (SHRs), 4-week-old rats were fed either a non-purified diet, a AIN76-purified diet or a AIN93G-purified diet for about nine weeks. In the first 1-2 weeks, the blood pressure was lower in the SHRs fed the AIN93G-purified diet than in those fed the non-purified diet. However, no significant difference in blood pressure was observed within the SHR group thereafter.

Selective radiofrequency catheter ablation of the slow pathway for common and uncommon atrioventricular nodal reentrant tachycardia

The utility of selective radiofrequency catheter ablation of the slow pathway for the treatment of common and uncommon atrioventricular nodal reentrant tachycardia (AVNRT) was studied in 110 consecutive patients, 94 with slow-fast form common AVNRT, and 11 and 5, respectively, with the fast-slow and slow-slow forms of uncommon AVNRT. Ablation sites were determined by mapping a late and spiky "slow pathway potential" in the posterior right atrial septum in common AVNRT, and also the earliest retrograde atrial activation over the retrograde slow pathway in uncommon AVNRT. AVNRT was successfully eliminated in all patients with a mean number of radiofrequency pulses of 2.9 +/- 3.0 and a mean total energy applied of 3536 +/- 2996 joules. There were no early or late complications, except for transient AV block for 15 sec immediately after energy application in one common AVNRT patient, and no recurrence of AVNRT in a mean follow-up period of 24 +/- 13 months. There were no significant differences between common and uncommon AVNRT in success rate, mean application number and total energy applied. However, the AVN physiology post-ablation was different. Slow pathway conduction was eliminated in only 32% of the patients post-ablation in common AVNRT, while it was elininated in 100% in uncommon AVNRT. Selective radiofrequency catheter ablation of the slow pathway can cure common and uncommon AVNRT effectively and safely. Common AVNRT can be eliminated irrespective of the persistence of slow pathway conduction, while uncommon AVNRT can be eliminated by the eradication of slow pathway conduction.

In vitro metabolism of a rifamycin derivative by animal and human liver microsomes, whole blood and expressed human CYP3A isoform

1. In vitro metabolism of a rifamycin derivative, benzoxazinorifamycin KRM-1648, was studied using mouse, rat, guinea pig, dog, monkey and human liver microsomes. 30-Hydroxy-KRM-1648 (M2) was produced in mouse, dog, monkey and human microsomes. 25-Deacetyl-KRM-1648 (M1) was produced in dog and human microsomes, but not in mouse or monkey microsomes. Neither M1 nor M2 was detected in rat or guinea pig microsomes. 2. In dog and human liver microsomes the formation of M2 was dependent on NADPH, but the formation of M1 was not. 3. In vitro metabolism of the parent compound was studied in whole blood in some species. Only M1 was detected in mouse and rat blood, and not in dog and human blood. 4. These findings demonstrated that the metabolite pattern in dog resembled that in man, and suggested that the 30-hydroxylation of KRM-1648 was mediated by cytochrome P450, but that the 25-deacetylation was not. 5. Among the ten recombinant human P450 isoforms used, only the cell lysates including CYP3A3 and CYP3A4 catalysed the M2 formation from KRM-1648.

Inhibition of mucosal lipid hyperoxidation by green tea extract in 1,2-dimethylhydrazine-induced rat colonic carcinogenesis

Phosphatidylcholine hydroperoxide (PCOOH) measured using a chemiluminescence detector to examine colonic mucosal lipid hyperoxidation increased after injection of 1,2-dimethylhydrazine and green tea extract (GTE), which we previously showed inhibited carcinogenesis and oxidative DNA damage in the gastrointestinal tract. Therefore, the hyperoxidation of membrane phospholipids reflected well the degree of DNA damage and carcinogenic alteration, and may be a useful intermediate biomarker for initiation of carcinogenesis.

Histological grade in invasive ductal carcinoma of breast correlates with the proliferative activity evaluated by BrdU: an immunohistochemical study including correlations with p53, c-erbB-2 and estrogen receptor status

Thirty cases of invasive ductal carcinoma of the breast were classified to histological subtype according to the General Rules for Clinical and Pathological Recording of Breast Cancer of the Japanese Breast Cancer Society and histologically graded using the Nottingham method and the correlation of histology with proliferative activity was investigated using bromodeoxyuridine (BrdU). In addition, the overexpression of p53 protein, c-erbB-2 oncoprotein and estrogen receptor (ER) were immunohistochemically examined in order to discuss the relationship with histological subtype and histological grade. Histological grade correlated positively to the BrdU labeling index (LI) and overexpression of p53. High grade carcinoma demonstrated c-erbB-2 more frequently and exhibited a low incidence of ER. However, no significant relationship was found between BrdU LI, overexpression of p53 and c-erbB-2 and histological subtype. These results suggest that the histological grade does represent the proliferative activity of tumor cells and that adding the histological grade to the pathological diagnosis in invasive ductal breast carcinoma may be useful from the clinicopathological aspect concerning tumor behavior.

Spatial and temporal expression of P-glycoprotein in the congenitally hydrocephalic HTX rat brain

The purpose of the present study is to examine spatial and temporal expression of P-glycoprotein in the brain of congenitally hydrocephalic HTX rats. P-glycoprotein has been reported not only as a drug efflux pump but also one of the factors that restricts brain edema. We examined the rat brain from postnatal day 1 to 60 using light and electron microscopy, immunohistochemistry, Western immunoblot and reverse transcriptase-polymerase chain reaction (RT-PCR) methods with monoclonal antibody specific for P-glycoprotein. Immunohistochemically, the positive anti-P-glycoprotein reactivity was found in capillaries of the normal control rat cerebrum. In the hydrocephalic HTX rat brains, it was also found in the capillaries, but only very weak to no reactivity was found in the capillaries of the spongy changes and cystic wall in the subcortical and lateral periventricular white matter. Immunoelectron microscopically, the reaction product was found exclusively on the luminal surface of the capillary endothelium in control rats. A tracer study with intracardiac perfusion of lanthanum chloride showed that lanthanum penetrated the tight junctions and passed through the intercellular space. In the Western immunoblot analysis, P-glycoprotein of 170 kDa was detected clearly in most normal control rat brains but it was not found in the hydrocephalic HTX rat brains. Moreover, mdr1 P-glycoprotein gene expression in the subcortical white matter was examined by RT-PCR. It was detected in all normal control rat brains, but not found in the hydrocephalic HTX rat brains. The results suggested that the absence of P-glycoprotein expression in the capillaries of deep subcortical and lateral periventricular white matter of hydrocephalic HTX rats led to a deficiency of the blood-brain barrier and might be related to vasogenic edema and to the formation of the spongy changes and cystic cavities.

[A case of cranial hypertrophic pachymeningitis with intracranial hemorrhage]

A case of cranial hypertrophic pachymeningitis of unknown etiology in a patient with 15-year history of headaches, cranial nerve palsies, and gait disturbance is reported. A 77-year-old woman was brought to our institute in a coma. CT revealed intracerebral hemorrhage in the right temporal lobe and thickening of the falx and tentorium. Fifteen years previously the patient had undergone CT scanning because of headaches, cranial nerve palsies, and progressive gait disturbance and a thickened tentorium, mild hydrocephalus and edematous change in the right temporal lobe had been reported. Since the etiology of her symptoms was unclear at the time, she did not receive adequate treatment. Her symptoms gradually progressed thereafter, and her visual acuity and hearing deteriorated. MR imaging in 1994 showed the thickened tentorium as a hypointense area with hyperintense edges on Gd-DTPA enhanced images. Angiography revealed narrowing of posterior portion of the superior sagittal sinus. The patient's condition rapidly deteriorated due to the intracranial hypertension and she subsequently died. Autopsy revealed a thickened tentorium with xanthochromic surface. This hypertrophic change was also seen in the dura mater of the posterior and middle cranial fossa. Microscopic examination of the thickened tentorium revealed extensive fibrous tissue with a chronic inflammatory infiltrate, predominantly of lymphocytes. No specific lesions were revealed by staining with hematoxylin-eosin, PAS, Gram's or Ziehl-Neelsen stains. The patient had no inflammatory or infectious diseases of other organs, and a diagnosis of idiopathic cranial hypertrophic pachymeningitis of unknown etiology was made. Considering the above findings, the thickened tentorium depicted as a hypointense area on the T1- and T2-weighted images and the Gd-enhanced edges of the tentorium are thought to be represent fibrous tissue and inflammatory regions, respectively.

Inhibitory effects and toxicity of green tea polyphenols for gastrointestinal carcinogenesis

BACKGROUND

Recently, and epidemiologic study showed a lower risk of gastrointestinal carcinogenesis in green tea drinkers. An experiment on two-stage skin carcinogenesis in mice showed that (-)-epigallocatechin gallate (EGCG), one of the main constituents of green tea, inhibited tumor formation.

METHODS

The inhibitory effects of EGCG and green tea extract (GTE) on N-ethyl-N'-nitro-N-nitroguanidine (ENNG)-induced duodenal carcinogenesis in the mouse, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced carcinogenesis of the glandular stomach in the rat, and azoxymethane-induced colon carcinogenesis in the rat were examined. The toxicity of GTE was assessed experimentally and GTE was applied clinically in normal volunteers to determine the effective dose and to assess its harmful effects.

RESULTS

EGCG and GRE inhibited chemical carcinogenesis of the gastrointestinal tract in rodents. Judging from the epidemiologic and experimental findings, it was determined that 1 g per day of GTE might be an effective dose. GTE was not toxic and no harmful effect was found during its clinical use.

CONCLUSIONS

These findings suggest that EGCG and GTE are useful in preventing gastrointestinal carcinogenesis, and the clinical usefulness of GTE, which has no harmful effects and is inexpensive, should be studied further.

Identification and antimicrobial activity of urinary metabolites of a rifamycin derivative in dog

1. Three metabolites of the antimicrobial agent 3'-hydroxy-5'-(4-isobutyl-1-piperazinyl)benzoxazinorifamycin (KRM-1648) were isolated from dog urine obtained after administration of a single oral dose. These metabolites of KRM-1648 were identified by mass spectrometry and 1H and 13C-nmr spectrometry. 2. Three metabolites of KRM-1648 were identified as 25-deacetyl KRM-1648, 30-hydroxy KRM-1648 and 25-deacetyl-30-hydroxy KRM-1648. 3. The antimicrobial activities of 25-deacetyl KRM-1648 were comparable with those of the parent compound, whereas 30-hydroxy KRM-1648 was equipotent and 2-8-fold less active than the parent compound against bacteria and mycobacteria, respectively.

Clinicopathological characteristics of gastric cancer in the elderly

The clinicopathological features of 380 elderly patients 70 years of age or older with gastric cancer were reviewed retrospectively from hospital records between 1969 and 1993. They were then compared with 1134 middle-aged patients between 40 and 69 years. The elderly constituted 18.4% of all gastric cancer patients 20 years ago but now comprise 24.4% of all patients in the most recent decade, despite the overall decrease in the rate of gastric cancer. The distinguishing histological features of gastric cancer in the elderly were an intestinal type of cancer, expansive tumour growth and synchronous multiplicity of the lesions. Elderly patients had a similar rate of tumour extension but had poorer survival as compared with the middle-aged patients. Post-operative death within 30 days after surgery was also higher in the elderly than in the middle-aged patients.

A quantitative visualization study of flow in a scaled-up model of a centrifugal blood pump

A quantitative flow visualization study of a scaled-up model of a centrifugal blood pump was performed. Since the size of the scaled-up model was three times as large as the original pump under development, and the kinematic viscosity of the saline solution used as the working fluid was approximately one-third that of the blood, we obtained a similar flow at one twenty-seventh the angular velocity of the original pump. The flow was visualized by seeding the saline solution with neutrally buoyant particles and by illuminating the model with a laser light sheet. Since the gap flow behind the impeller is important for thrombus formation, it was recorded by a high-speed video camera, and the velocity field was evaluated automatically by particle tracking velocimetry. It was shown that in the gap behind the impeller there existed a region where the velocity profile was almost flat which can be called a core region. The results indicated the effectiveness of the present visualization technique for centrifugal blood pumps.

Molecular analysis of the poly(3-hydroxyalkanoate) synthase gene from a methylotrophic bacterium, Paracoccus denitrificans

A 3.6-kb EcoRI-SalI fragment of Paracoccus denitrificans DNA hybridized with a DNA probe carrying the poly(3-hydroxyalkanoate) (PHA) synthase gene (phaC) of Alcaligenes eutrophus. Nucleotide sequence analysis of this region showed the presence of a 1,872-bp open reading frame (ORF), which corresponded to a polypeptide with a molecular weight of 69,537. Upstream of the ORF, a promoter-like sequence was found. Escherichia coli carrying the fusion gene between lacZ and the ORF accumulated a level of poly(3-hydroxybutyrate) that was as much as 20 wt% of the cell dry weight in the presence of beta-ketothiolase and acetoacetylcoenzyme A reductase genes of A. eutrophus. The ORF was designated phaCPd. A plasmid vector carrying the phaCPd'-'lacZ fusion gene downstream of the promoter-like sequence expressed beta-galactosidase activity in P. denitrificans. When a multicopy and broad-host-range vector carrying the ORF along with the promoter-like sequence was introduced into P. denitrificans, the PHA content in the cells increased by twofold compared with cells carrying only a vector sequence.

Growth-Associated Production of Poly(3-Hydroxyvalerate) from n-Pentanol by a Methylotrophic Bacterium, Paracoccus denitrificans

Paracoccus denitrificans accumulated a polyester in its cells during growth on n-pentanol. The composition of the polyester varied during the cultivation: the level of the 3-hydroxyvalerate unit in the polyester increased, and eventually a homopolymeric poly(3-hydroxyvalerate) [P(3HV)] accumulated to an amount 22 to 24% of the cell dry weight. Growth-associated polyester synthesis was considerably affected by n-pentanol when its concentration was controlled at several levels. Maximum accumulation of the polyester was obtained at 0.02% (vol/vol). Physical and mechanical characteristics of the P(3HV) were determined and compared with those of other homo- and copolyesters. The P(3HV) was dextrorotatory and had number-averaged and weight-averaged molecular masses of 128,000 and 888,000 Da, respectively, with a rate of polydispersity of 6.93. The level of tensile strength of the P(3HV) was lower, and its extension to break was higher than that of the poly(3-hydroxybutyrate) homopolyester.

Functional linkage of the cardiac ATP-sensitive K+ channel to the actin cytoskeleton

The role of the cytoskeleton in the rundown and reactivation of adenosine triphosphate (ATP) sensitive K+ channels (KATP channels) was examined by perturbing selectively the intracellular surface of inside-out membrane patches excised from guinea-pig ventricular myocytes. Actin filament-depolymerizing agents (cytochalasins and desoxyribonuclease I) accelerated channel rundown, while actin filament stabilizer (phalloidin) or phosphatidylinositol biphosphate (PIP2; inhibitor of F-actin-severing proteins) inhibited spontaneous and/or Ca2+-induced rundown. When rundown was induced by cytochalasin D or by long exposure to high Ca2+, channel activity could not be restored by exposure to MgATP, but application of F-actin with MgATP could reinstitute channel activity. The processes of rundown and reactivation of cardiac KATP channels may thus be influenced by the assembly and disassembly of the actin cytoskeletal network, which provides a novel regulatory mechanism of this channel.

Roles of lysine-69 in dimerization and activity of Trimeresurus flavoviridis venom aspartate-49-phospholipase A2

Trimeresurus flavoviridis (Habu snake) venom aspartate-49-phospholipase A2 (Asp-49-PLA2) was reacted at pH 9.0 with a 2-fold molar excess of 2,4,6-trinitrobenzenesulfonate in the absence of Ca2+ and two trinitrophenylated derivatives were isolated by HPLC. One was a derivative modified at Lys-11 and its activity was mostly retained. The other was a derivative modified at both Lys-11 and Lys-72 and its activity was 40% that of unmodified enzyme. Trinitrophenylation of Lys-72 appeared to bring about a conformational disorder at the lipid-water interface recognition site and thus a reduction of activity. When the enzyme was modified in the presence of Ca2+, activity decreased at a rate much faster than that in the absence of Ca2+ and Lys-69 came to be modified. These results suggested that conformational displacement of Asp-49-PLA2 of a local to global type occurs upon the binding of Ca2+. The derivative modified at Lys-69 had 28% activity and existed as a monomer. This supports a previous assumption that Lys-69 participates in dimerization of group II Asp-49-PLA2s [Brunie et al. (1985) J. Biol. Chem. 260, 9742-9749] and shows that dimerization is not necessarily essential for activity manifestation.