Substrate-induced membrane association of phosphatidylserine synthase from Escherichia coli

To better establish the intracellular location of the phosphatidylserine synthase of Escherichia coli and hence better understand how it is regulated in the cell, we compared the size, function, and binding properties of the enzyme made in vitro with the enzyme found in cell lysates and with the purified enzyme. The enzyme made either in vivo or in an active form in vitro was found primarily associated with the ribosomal fraction of the cell and had the same apparent molecular mass as the purified enzyme. These results were unaffected by the presence of protease inhibitors. Addition of unsupplemented E. coli membranes or membranes supplemented with phosphatidylethanolamine did not affect the subcellular distribution of the enzyme in these experiments. However, addition of membranes supplemented with either the lipid substrate, CDP-diacylglycerol, or the lipid product, phosphatidylserine, resulted in membrane association by the enzyme rather than ribosomal association. Addition of membranes supplemented with acidic lipids also brought about membrane association, but this association was primarily ionic since it was disrupted by high salt concentrations. These results strongly suggest that the ribosomal location of this enzyme is not the result of some modification event occurring after cell lysis and that the normal functioning of the enzyme involves membrane association which is primarily induced by the presence of a membrane-associated substrate.

Structure and expression of the gene locus encoding the phosphatidylglycerophosphate synthase of Escherichia coli

This paper presents definitive results which establishes a direct gene-protein product relationship between the pgsA gene and the phosphatidylglycerophosphate synthase of Escherichia coli. The predicted protein sequence derived from the determined DNA sequence of pgsA is in close agreement with the amino acid composition and partially determined amino acid sequence of the purified enzyme. The purified synthase has the same apparent molecular mass as the gene product made by a plasmid-directed transcription-translation system. The plasmid-borne copy of the pgsA gene is also capable of expressing enzymatically active synthase in vitro. The DNA sequence analysis has established the exact linear relationship between the uvrC, pgsA, and glyW loci and revealed that these three genes are transcribed in the same direction. The terminal coding regions of these three genes also share common sequences with transcriptional regulatory elements for the adjacent genes.

Bandage backfall: labyrinthine and non-labyrinthine components

A cataleptic animal clings in a vertical position, unmoving, for abnormally long periods by supporting some of its weight on its hindlegs, grasping with the forepaws, flexing its forelimbs, and holding the head horizontal. When the head is snugly wrapped with a bandage, the head slowly falls backward, the neck hyperextends, the forelimbs extend and the grasp is released, resulting in the animal falling backward to the ground. It was earlier suggested that in cataleptic animals, the bandage inhibits vestibular and kinesthetic mechanisms of head support, yielding the backfall sequence [35]. However, preliminary experiments showed that labyrinthectomized rats made cataleptic by haloperidol fall backwards when placed in a vertical clinging position, even without a bandage, suggesting that in the rat the bandage-backfall reaction depends only on the vestibular system. In the present paper, this result is verified but, by additional experiments, the latter conclusion is shown to be incorrect. In labyrinthectomized rats made cataleptic by other means (lateral hypothalamic damage, or bulbocapnine), backfall from clinging did not occur unless a bandage was applied. Therefore, the bandage does indeed appear to inhibit the kinesthetic mechanisms that maintain head support in labyrinthectomized cataleptic rats. Haloperidol, particularly in high doses, greatly weakens postural support in labyrinthectomized rats (causing the animal to sag down and fall back when clinging), although the effect is not detectable in rats with labyrinths intact. However, labyrinthectomy reveals that the bandage can trigger an active dorsiflexion of the neck which in itself appears to inhibit clinging and righting. Bandage-induced dorsiflexion is present to a much lesser degree in intact animals, indicating that labyrinthine mechanisms inhibit the dorsiflexion reflex. Therefore, in the intact, cataleptic rat the bandage backfall reaction appears to be produced by the combined effects of a passive component (inhibition of kinesthetic support mechanisms), and an active component (elicitation of dorsiflexion of the neck).

Head displacement and bracing in haloperidol-treated rats compared to rats with lateral hypothalamic damage

A characteristic of catecholamine-depletion-induced catalepsy is that such animals resist horizontal displacement, forward, backward or sideward, by bracing, i.e., pushing against the displacing force rather than stepping away as do normal animals. In this report the bracing responses of two cataleptic preparations were compared: (1) intact rats given haloperidol, a dopamine antagonist, and (2) rats with large lesions of the lateral hypothalamus (LH). Although both preparations exhibited exaggerated bracing responses when pushed, the LH rats acted in a non-cataleptic manner when pushed backward by the head; they retreated backward. The backward walking was a head-elicited response, because pushing the body backwards by the shoulders elicited bracing, not walking. Other forms of head displacement elicited body bracing if the body's stability was challenged: as when the head (and thus the body) was pulled forward; or no strong bracing responses if the head was displaced without affecting the body's stability, i.e., when as the head was pushed laterally. Therefore, retreating rather than bracing was elicited by one specific form of head displacement: backward. In contrast, haloperidol-treated rats braced whenever the body's stability was challenged, including when the head was pushed backward.

Relationship between the R-R interval variation and metabolic states of diabetes

To investigate whether the metabolic state of diabetes affects the R-R interval variation, 82 diabetics were studied at intervals of about 1 month and of about 1 year. There was no significant relationship between the rate of change for FBG and that for R-R interval variation at both these intervals. However, in the cases that showed a change of HbA1 by more than 10% in a month, the rate of change for the R-R interval variation was 20 +/- 30% in the group with improved HbA1 and -9 +/- 17% in the group with aggravated HbA1, demonstrating a significant difference (P less than 0.05) between the 2 groups. There was a significant difference (P less than 0.02) in the rate of change for the R-R interval variation between the group with improved HbA1 by more than 5% and the group with aggravated HbA1 by more than 5%, when measured at intervals of 1 year. No special relationship was observed between the difference in R-R interval variation and each of the following: (1) the mean FBG for 1 year preceding the day of initial measurement of the R-R interval variation; (2) the mean FBG for the succeeding year; and (3) the difference in these 2. It was suggested that the R-R interval variation was likely to be affected by the metabolic state during the preceding 1-2 months.

State of hepatitis B virus DNA in leucocytes of hepatitis B patients

Hepatitis B virus (HBV) DNA in leucocytes from 50 hepatitis patients with various patterns of HBV serological markers and serum HBV DNA and 13 normal controls were examined by Southern blot hybridization with 32P-labeled 3.2 Kb HBV DNA. A free form of HBV DNA was observed in leucocytes of 8 patients, 7 of whom were positive for serum HBeAg, and in 6 patients an integrated form of HBV DNA was identified. HBV DNA was not identified in leucocytes from 13 normal controls. The free form of HBV DNA in leucocytes existed as a heterogeneous smear from 2.0 to 3.2 Kb, similar to the pattern in liver and hepatocellular carcinoma cells but different from serum HBV DNA in which the 3.2 Kb band was absent. The banding pattern of the integrated form of HBV DNA in leucocytes varied among different patients. During preparation of white blood cells and purification of HBV DNA probes, it was important to remove plasma contamination and traces of pBR322, respectively. The presence of extrachromosomal DNA sequences partially homologous to pBR322 could cause false results. The presence of a free and integrated form of HBV DNA in leucocytes is important for explaining the biology of HBV, the harbouring and replication sites of extrahepatic origin, the mechanism of recurrent infection, and the rationale of the treatment of hepatitis B.

Alternate substrates and inhibitors of bacterial 4-hydroxyphenylpyruvate dioxygenase

A variety of analogues of (4-hydroxyphenyl)pyruvic acid were synthesized, and the reactions of these compounds with the 4-hydroxyphenylpyruvate dioxygenase from Pseudomonas sp. P.J. 874 were examined. Several of the ring-substituted substrate analogues are reversible inhibitors of the enzyme, the most potent being the competitive inhibitor (2,6-difluoro-4-hydroxyphenyl) pyruvate (Ki = 1.3 microM). Two substrate analogues (2-fluoro-4-hydroxyphenyl)pyruvate and [(4-hydroxyphenyl)thio]pyruvate proved to be alternate substrates for the enzyme. The former compound is converted to (3-fluoro-2,5-dihydroxyphenyl)acetate in an essentially normal catalytic sequence including oxidative decarboxylation, ring hydroxylation, and side-chain migration. The latter compound, however, undergoes oxidative decarboxylation and sulfoxidation to give [(4-hydroxyphenyl)sulfinyl]acetate; ring oxidation is not observed. The implications of these results with regard to the catalytic mechanism of 4-hydroxyphenylpyruvate dioxygenase are discussed.

Fractionation of the cataleptic bracing response in rats

In haloperidol-treated rats, bracing, i.e., resistance to displacement along a horizontal surface, was found to involve four components: gripping by the digits, extension by the limbs, stiffening of the body axis and arching the vertebral column towards the displacing force. Labyrinthectomy weakened the bracing of the forequarters as did application of a head bandage. Labyrinthectomy, when combined with head bandage, completely abolished all forequarter bracing responses. Neither manipulation affected the bracing responses of the hindquarters. The hindquarter bracing reaction was abolished by application of an abdominal bandage, which left most of the forequarter responses intact. Isolation of fore- and hindquarter bracing responses revealed that whereas gripping by the digits and extension by the limbs could occur independently in either part of the body, stiffening of the body axis and arching of the vertebral column originated in the hindquarters. However, although these latter components of bracing originate in the hindquarters, as evidenced by their abolition with application of an abdominal bandage, their recruitment into the anterior of the body only occurred when the bracing of the forequarters was unimpaired. Either labyrinthectomy or head bandage prevented stiffening and arching of the vertebral column from occurring in the forequarters, even though these procedures had no effect on the hindquarters. Labyrinthectomy, head bandage and abdominal bandage all fractionated the bracing response over a wide range of haloperidol dosages (0.5, 1.0, 2,5, 5,0 and 7.5 mg/kg).

Cholangiocarcinoma in hepatolithiasis

During the period of 1979-1982, 10 cases of cholangiocarcinoma associated with hepatolithiasis were seen. We report the clinical features of 10 cases of cholangiocarcinoma in association with hepatolithiasis, along with detailed histopathology from the four resected specimens. Our observations suggest that whenever intrahepatic stones are encountered in patients over 50 years of age with a long history of recurrent cholangitis and intractable pain, further examination including echo-guided aspiration cytology, liver scanning, and peritoneoscopy should be performed to rule out a coexisting cholangiocarcinoma.

Laminar-related projection of primary trigeminal fibers in the caudal medulla demonstrated by transganglionic transport of horseradish peroxidase

The mode of termination of primary afferent fibers within the cat trigeminal nucleus caudalis was investigated by means of the transganglionic transport of horseradish peroxidase (HRP). Several types of laminar-related labeling were observed, depending upon the survival time after HRP application. At the earliest survival time (28-34 h) the highest density of labeling was found in laminae I and II. At 2 and 3 days survival laminae III and IV were heavily labeled, in addition to laminae I and II where the amount of labeling was greatly increased in lamina I, but not in lamina II. At 5 days survival time an abrupt drop of labeling occurred in laminae I and II, while this pattern was not predominant in laminae III and IV. In lamina V the pattern of labeling was less intense and not changeable through all survival times observed. These findings indicating a differentiation of the primary afferent terminals have good correspondence with a functional specialization of neuronal locations since the functional properties of neurons vary according to their locations.

Classification of Agkistrodon species in China

The wide geographical distribution of Agkistrodon and the slight morphological differences among the snakes of the genus Agkistrodon in China have posed a problem to taxonomists. We have employed polyacrylamide gel electrophoresis and immunological diffusion techniques for comparison of the venoms of different species and subspecies of Agkistrodon from various localities. The electrophoretic patterns of the proteins of the venoms were different from each other, but showed certain relations within species and subspecies. We used Ouchterlony double diffusion of a rabbit antiserum against the purified "neurotoxin" from the venom of Agkistrodon blomhoffii brevicaudaus (from the Zhejiang Province of China) on the various venoms of Agkistrodon. Precipitin lines formed with immunological identity between the same species, partial identity between closely related species and no precipitin line between different species. Combining experimental data, morphological characteristics and geographical distribution, we propose that the genus Agkistrodon (sensu stricto) in China consists of seven species and subspecies: (1) Agkistrodon blomhoffii brevicaudus Stejneger, (2) A. b ussuriensis Emelianov, (3) A. intermedius (Strauch), (4) A. saxatilis Emelianov, (5) A. shedaoensis Zhao, (6) A. strauchii Bedriaga, (7) A. monticola Werner. Agkistrodon acutus (Guenther) has recently been changed to a new genus, Deinagkitrodon, established by Gloyd in 1978.

The reduction of platelet thrombi on damaged vessel wall by a thromboxane synthetase inhibitor in rabbits

The role of thromboxane A2 (TXA2) in platelet-vessel wall interaction was investigated using 1-benzylimidazole (1-BI), a selective thromboxane synthetase inhibitor. 1-BI (0.9 mM) will reduce the aggregatory response of rabbit platelets to 0.2 mM arachidonate by 50% and their production of TXA2 by 84%. The effect of 1-BI on platelet thrombus formation was evaluated in vivo on New Zealand white male rabbits using the autologous indium-111 labeled platelet technique. After injection of autologous 111In-platelets, 10 cm of the abdominal aorta was de-endothelialized with a balloon catheter. Three hours later the animals were sacrificed and injured and uninjured segments of the aorta removed. The radioactivity and dry weight of the tissue were determined. The radioactivity/gm of tissue was greater for the injured tissue than for the uninjured tissue. 1-BI at 10 mg/kg reduced the specific platelet accumulation at the injured site (n = 5; 4.8 +/- 0.3 X 10(5) cpm/gm) compared to the controls (n = 10; 11.7 +/- 2.1 X 10(5) cpm/gm). Platelet accumulation on the injured tissue was further reduced by increasing the dosage to 30 mg/kg. Thirty minutes after 1-BI administration (30 mg/kg), platelets were less sensitive to arachidonate-induced aggregation (a 67% decrease) and TXA2 production was decreased 82%. Alterations in platelet sensitivity persisted for up to 3 hours. These findings indicate that TXA2 plays an important role in platelet-vessel wall interaction.

Inhibitory activity of the new adamantane derivative N,N'-bis(ethylene)-P(1-adamantyl)-phosphonic diamide against Rous sarcoma virus

A new adamantane derivative N,N'-bis (ethylene)P(1-adamantyl)-phosphonis diamide, was found to inhibit Rous sarcoma virus replication in much the same manner as reported for the parent compound, 1-adamantanamine hydrochloride.

Accelerated prostacyclin degradation in the thrombotic thrombocytopenic purpura

Plasma prostacyclin (PGI2) degradation rate was measured in a 39-year-old man with chronic thrombotic thrombocytopenic purpura (TTP). His disease responded to plasma exchange, or plasma infusion alone, given at 3-4 week intervals. Plasmapheresis with albumin replacement had an adverse effect. PGI2 degradation rate was measured by incubation of exogenous PGI2 with plasma at 37 degrees C and recording of PGI2 activity after one, five, and fifteen min incubation by measurement of inhibition of platelet aggregation. The PGI2 degradation rate of the patient was significantly higher than that of normal subjects. The degradation rate improved after each plasma treatment and correlated well with clinical improvement. Moreover, the degradation rate of PGI2 could be corrected in vitro by the addition of normal plasma. When the patients plasma was incubated with aortic rings, PGI2 activity was reduced but the level of its inactive end product, 6-keto-PGF1 alpha, was normal. These findings indicate that our patient had normal PGI2 stimulating activity but had an abnormal rate of PGI2 degradation. Accelerated PGI2 degradation which leads to PGI2 deficiency may be important in the pathogenesis of microvascular thrombosis.

Differential effects of two doses of aspirin on platelets-vessel wall introduction in vivo

Platelet cyclooxygenase appears to be more sensitive to aspirin than the arterial endothelial cell cyclooxygenase. To investigate the dose-related effects of aspirin on platelet-vessel wall interaction in acute vascular injury, male New Zealand White rabbits were treated with either (a) aspirin (150 mg/kg body wt; n = 6), (b) aspirin (30 mg/kg; n = 6), or (c) vehicle (n = 10). After treatment, autologous 111In-platelets were injected and deendothelialization of a 10-cm long segment of abdominal aorta was induced by a balloon catheter. Rabbits were killed 3 h after injury and radioactive counts and percentages of injected radioactivity per gram dry weight of tissue or blood were determined. The 30 mg aspirin group had a significantly lower radioactive count (62.13 +/- SD 6.07 x 10(3) cpm) and percentage of injected radioactivity (0.024 +/- 0.003%) per gram dry weight of damaged aortic tissue than the control (1,167.82 +/- 212.31 x 10(3) cpm/g tissue and 0.435 +/- 0.079%, respectively). By contrast, the 150-mg aspirin group had an elevation of radioactive counts (4,343.12 +/- 556.98 cpm) and percentage (1.632 +/- 0.246%) per gram dry weight of damaged tissue. Infusion of exogenous PGI2 was associated with reduction of lesion radioactivity. These findings were supported by ultrastructural findings. Examined under transmission electron microscopy, the injured aortic wall of 30-mg group was covered throughout the segment by a single layer of platelets without detectable platelet aggregates, while that of the 150-mg group was diffusely packed with multiple layers of platelets. The findings demonstrate that aspirin (30 mg/kg) prevents platelet aggregate formation at the injured arterial wall, whereas 150 mg/kg promotes platelet thrombus formation.

Abnormal platelet response to thromboxane A2

To determine the pathogenetic mechanism of a hereditary primary platelet release disorder, arachidonic acid metabolism via the cyclooxygenase pathway was investigated. The propositus' platelets exhibited defective release reaction and second-wave aggregation when stimulated by sodium arachidonate or U46619, a thromboxane A2 (TXA2) agonist. The lack of platelet response to U46619 suggested that the defect was beyond the thromboxane synthetase level. Furthermore, thromboxane B2 (TXB2) formation in the propositus' platelets (558.52 ng/10(8) platelets) was within the normal range (574.29 +/- SD 27.39 ng/10(8) platelets) and TXA2 formation appeared to be adequate for aggregating normal platelets. The results were indicative of an abnormal platelet response to TXA2. Failure of the propositus' platelets to aggregate in response to TXA2 formed in normal platelet-rich plasma induced by arachidonate confirmed this notion. To gain further insight, platelet cyclic (c) AMP content was determined. Prostacyclin induced a significant elevation of the propositus' platelet cAMP level comparable to normal values. U46619 suppressed prostaglandin I2-induced cAMP elevation in normal subjects but had no such effect in the patient. We conclude that the primary release disorder observed in this kindred is due to an abnormal platelet respnse to TXA2 possibly because of TXA2/PGH2 receptor abnormalities.

Hereditary bleeding disorder due to a primary defect in platelet release reaction

A large family with a hereditary bleeding disorder was investigated. Easy bruising, epistaxis and menorrhagia were noted in seven members of three generations and at least one member in each generation was affected. Platelet function abnormalities were characterized by reduced 14C-serotonin release, absent second wave aggregation in response to ADP or epinephrine and reduced aggregation in response to collagen. Bleeding time was prolonged in three individuals and platelet factor 3 availability was abnormal in four. Platelet count, morphology, adhesiveness and clot retraction were normal in all. Platelet ADP and ATP as well as ATP to ADP ratio were normal. This family probably represents the first documented instance of hereditary platelet primary release disorder. To elucidate the pathogenetic mechanism, further functional studies were performed. No appreciable shape change, 14C-serotonin release of aggregation was observed when the propositus' platelets were stimulated with sodium arachidonate or a PGH2 analogue. By contrast, platelets responded normally to ionophore A23187, thrombin and ristocetin. The findings indicate that the hereditary primary release disorder is probably due to a reduced thromboxane A2 production secondary to thromboxane synthetase deficiency. Alternatively, it may be due to platelet membrane abnormalities which render platelets unresponsive to thromboxane A2.

Effect of ribavirin on Rous sarcoma virus transformation

Ribavirin inhibited the expression of cellular transformation in normal rat kidney cells transformed by a temperature-sensitive mutant of rous sarcoma virus and chicken embryo fibroblasts infected with either a temperature-sensitive mutant or wild-type Rous sarcoma virus. Ribavirin also inhibited replication of the Rous sarcoma viruses in chicken embryo fibroblasts. The effect of ribavirin on cellular transformation was not permanent, as removal of the drug resulted in reversion to the transformed phenotype. The concentration of ribavirin necessary to inhibit the expression of cellular transformation was cytostatic for the cell lines used in this study.

A comparison of methods for the study of platelet hyperfunction in thromboembolic disorders

To gain insight into the interrelationship of various methods for the study of platelet hyperfunction, we compared plasma beta-thromboglobulin (beta-TG), circulating platelet aggregates (CPA), and ADP-induced platelet aggregation in 119 patients with thromboembolic disorders and 28 control subjects. CPA correlated fairly well with beta-TG, suggesting that both methods measure similar in vivo platelet activation and aggregation. CPA had an excellent correlation with platelet survival half-time. In contrast, there was a poor correlation between in vitro platelet aggregation and CPA or beta-TG. These results confirm the notion that both CPA and beta-TG procedures are suitable for determination of in vivo platelet activation whereas platelet aggregation technique has serious limitations to test in vivo platelet activity. In order to have an accurate assessment of platelet hyperfunction, a battery of tests are needed.

Reduced platelet sialyltransferase activity in patients with primary release disorder

Platelet sialyltransferase activity was determined in four patients with primary platelet release disorder. Basal enzyme activity was significantly reduced in all. Moreover, enzyme activity in response to stimulation by collagen or sodium arachidonate was also reduced. Platelet total and surface sialic-acid content was normal. The results indicate that defective membrane sialytransferase may be involved in the pathogenesis of primary platelet release disorder.

Impaired cell-mediated immunity function in thyroid cancer

Immunological parameters were studied in 31 patients with thyroid cancer. Serum immunoglobulin levels, T and B cell percentages in peripheral blood, showed no significant difference as compared with those of control group. The blastogenesis with phytohemagglutinin P (PHA) was significantly reduced, especially, in those having larger tumor size or metastasis or in those over age 60. The positive rate of skin test with purified-protein-derivative (PPD) and Streptokinase-Streptodornase (SK-SD) was also markedly reduced. The impaired blastogenesis of lymphocyte and reduced positive rate of skin test in those cancer patients suggested that the cell-mediated immunity function, in spite of adequate count of T-cells, was impaired.

Mouse DNA polymerase alpha. Subunit structure and identification of a species with associated exonuclease

Two species of alpha-polymerase with very similar catalytic properties have been purified to near homogeneity from a soluble protein fraction of mouse myeloma. Sedimentation analysis in 0.5 M salt-containing glycerol gradients indicated that both species had a native Mr of about 190,000. Each species contained nonidentical subunits with apparent molecular weights of about 47,000 and 54,000. Subunits of Mr = approximately 50,000 had been found previously in calf thymus alpha-polymerase (Holmes, A. M., Hesslewood, I. P., and Johnston, I. R. (1974) Eur. J. Biochem. 43, 487-499; (1976) Eur. J. Biochem. 62, 229-235). Tryptic peptide mapping failed to reveal primary structure homology between the subunits of the two enzymes. Thus, the two alpha-polymerases are clearly different species. These two enzymes are further distinguished by the fact that one of them has associated exonuclease activities. One activity degraded single-stranded DNA to mononucleotides in the 3' leads to 5' direction and acted distributively. The other exonuclease activity also degraded single-stranded DNA to mononucleotides, but this degradation was in the 5' leads to 3' direction in a processive fashion. Both exonuclease activities co-migrated with the polymerase activity during the final purification step of polyacrylamide gradient gel electrophoresis, which yielded the essentially homogenous alpha-polymerase, and also during sedimentation of the purified enzyme through a high salt glycerol gradient.

Arthroscopy of the wrist and finger joints

Ninety arthroscopies of the wrist and finger joints in 34 clinical cases and two amputated arms were carried out with the number 24 arthroscope. Eighty-four wrist and finger joints of four cadavers and two amputated arms were also dissected for macroscopic observation. Most portions of the interior structures of the wrist and finger joints can be observed by the dorsal approaches. Color photography and punch biopsy are also possible. Some arthroscopic photographs taken with the number 24 arthroscope are illustrated. From these experiences it is concluded that the number 24 arthroscope is a useful diagnostic tool in arthroscopy of the small joints, even though there are still many problems.

Purification and characterization of the anticoagulant principle of Trimeresurus mucrosquamatus venom

By means of CM-Sephadex column chromatography, Trimeresurus mucrosquamatus venom was separated into 20 fractions. Fraction XX had the marked anticoagulant action. This fraction was refractionated three times on Sephadex G-75, and a single peak was obtained. The patterns of microzone and disc electrophoresis also showed a single band. A single, symmetrical boundary with a value of 1.61 S was obtained by ultracentrifugation. It was a single peptide chain with a molecular weight of 11 700. The isoelectric point was higher than pH 10. The anticoagulant principle possessed phospholipase A activity and was calcium ion dependent. It did not possess proteolytic, tosyl-L-arginine methyl ester esterase, phosphodiesterase and alkaline phosphomonoesterase activities of the crude venom. The phospholipase A activity was heat-labile at pH 7.4, but was heat-stable at pH 5.6. The anticoagulant activity was more resistant to heat treatment as compared with phospholipase A activity. The anitoagulant action of the purified principle was competitively inhibited by platelet phospholid, tissue thromboplastin and cephalin, and was neutralized by antiserum. The anticoagulant principle inhibited platelet aggregation induced by ADP. It did not destroy fibrinogen, Factor X, prothrombin and thrombin; nor did it induce fibrinolysis nor interfere with the interaction between thrombin and fibrinogen. It is concluded that the anticoagulant action of this phospholipase A was due to the inhibition of the activations of Factors X and II through the inactivation of the procoagulant activity of phospholipids mediated partly by phospholipid-binding activity of this venom enzyme and partly by its enzymatic hydrolysis of phospholipids.