Andre de Vries

VENOM PHOSPHOLIPASE A: A REVIEW.

TIB3 cENERic term phospholipase designates a class of enzymes which specifically hydrolyze phospholipids. Four types of phospholipases are known-phospholipase A, B, C, D ; they are individually characterized by a specific site ofaction on the phospholipid molecule. Phospholipase A (phosphatide aryl hydrolyze, EC 3.1 .1 .4) catalyzes the hydrolysis of one ester bond in phosphatide molecules with formation of lysophosphatides and release of free fatty acids. The other phospholipases attack the phosphatide molecules at different site. Phospholipase B (EC 3.1 .1 .E splits off the fatty acid of lysophosphatide ; phospholipase C (EC 3.1 .4 .3) effects hydrolytic rupture of the phosphorylated nitrogen base with formation of a, s diglyceride, and phospholipase D (EC 3.1 .4.4) splits the nitrogen basephophoric acid ester bond with production of phosphatidic acid . Snake and bee venoms are the most potent known sources of phospholipase. As far as known they contain phospholipase A only. Phospholipase A has been identified in all snake venoms tested, whether beloning to theViperidae, Elapidae or Crotalidae families [1,2,3,4]. Phospholipase A has also been detected in bacteria [5] and in body tissues and fluids . Ox and human pancreas are especially rich in phospholipase A [6,7] and the presence of the enzyme in duodenal content, pancreatic juice, bile, serum [8,9] and in brain [10] has been demonstrated .

Accelerated erythrocyte 5-phosphoribosyl-1-pyrophosphate synthesis. A familial abnormality associated with excessive uric acid production and gout

Abstract Increased erythrocyte PRPP content and enhanced in vitro erythrocyte PRPP generation was found in two gouty brothers having excessive uric acid production and normal erythrocyte HGPRT activity. The transmission of the metabolic defect in this family is compatible with the recessive X -linked mode of inheritance.

The direct lytic factor of cobra venom: purification and chemical characterization

Abstract The direct lytic factor (DLF) from the venom of Ringhals ( Haemachatus haemachates ) was isolated and purified by successive application of trichloroacetic acid and salt precipitation. The purified DLF is homogeneous by ultracentrifugal and electrophoretic criteria and is about twice as active as the material isolated previously by paper electrophoresis. DLF is a single-chain protein with a molecular weight of 7000. It contains 57 amino acid residues cross-linked intramolecularly by 4 disulfide bridges. Leucine is in the amino terminal position, and serine in the carboxyl terminal position of the protein. DLF causes inhibition of growth in some bacteria.

Actin-linked regulation of the human platelet contractile system

R a d i a t i o n o f musclu eontraegon in~ol~.es two basle ra:eeharsisms. Ixa vertebrate mxlscles Ca 2÷ ¢onl~ols eontraeli~n by b,mding to t~opo~fin located on the t~opomyosin--aelin ~on~aining thin f, flament [1, 2]. In molluscan muscles ii-oponin is absem and ~he caMum ~egulafion is ef£ected through b~d~ng t,o myosin !ight chains I3]We laa~e prevao~ly demonstrated that in human plNelels, similarly ~o rnnsele zyzxems~ a saturating level of 10 -6 M Ca 2+ is req ,tfir,ed t.o swStch on the natu~at a~tomyosin(,thlomboalh~nin) Mg-ATPas~ a~tivhy I4]. Furthermore, we have is.o]at.ed f ;om hnmma p]a~e].ets a txopomyosin-like protein, possibly i n t o n e d in the contraet~,e regulatory xyst,em [,4]. II1 order to ~ltacidat.~ ~h= ~aee~anizan o f pla~elet .conI~a~Iile regulation we applied a p.rineiple recently pm Nrward by l ehman e t at. [5]. In ~he absence o f Ca 2+, the Iegulato,ry proteins, bound t,o the actin thin filament in vertebrates anda r th ropods and to myosin in rno!lus~a and lowex organisms, pyeva~t interact,ion between actin and myosin, anti :as a result the Mg-ATPase aeti~fi~y is depressed. In the case o f ve.~tebzate amd adhr0p0d m~de, pure act;m (tr0pornyosinand l :oponin-free) added to .an actomyoaSn system ~ the • absence ~f,Ca ~ tnrns ~n the .]V!g-ATPase activity; th~s fhe actin interacts dheedy with the inyosin. ,On I~e o t h ~ t~nfl , k ~he ease ,of molh~ean m-ascle whe~e-the xeg,ul-at0ry system is bound t o myosin [3], pure actin :added to actomyostn in the absence o f Ca 2 . .cannot interact wi th rnyo~7. The appliea~don o f this pfincip]e ~o the human platelet conlraeti!e system and the presently 6b.ser~ed ~egu_lgtion conferred on rabbit my.o~n ATPase activity b y platelet th in fillament~ Ira highly indicative ,that the-regulation ofp!a te te t con~ract~on is Of the acfin-linked type.

Actin-activated ATPase from human erythrocytes

A fibrillar protein complex, possessing ouabain-insensitive Ca2+-ATPase activity was isolated from human erythrocyte membranes by using a low ionic strength extraction procedure. Mg2+-ATPase activity was revealed upon addition of rabbit skeletal muscle actin, thus demonstrating the presence of a myosin-like protein in the crude extract of the erythrocyte membrane. Upon sodium dodecylsulfate gel electrophoresis, the extract showed mainly the doublet of subunit molecular weight bands of 230 000 and 210 000, and more than 10 faster moving bands. Gel filtration of the erythrocyte membrane extract on Sepharose 4B furnished 4 fractions. Fraction I, containing the doublet and 80 000, 60 000 and 46 000 subunit molecular weight bands was 5-fold purified with respect to Ca2+-ATPase activity, but was devoid of actin-activated Mg2+-ATPase activity. Fraction II, containing only the doublet, was devoid of Ca2+ and actin-activated Mg2+-ATPase activity. The 210 000 subunit molecular weight protein could be phosphorylated in the presence of Mg2+ in the crude extract and Fraction I but not in Fraction II.

Evidence for X-Linkage of Phosphoribosylpyrophosphate Synthetase in Man

Skin fibroblast cultures were utilized to study the mode of inheritance of a mutant feedback-resistant phosphoribosylpyrophosphate synthetase in a gouty family with purine overproduction. Selective conditions were applied to allow the survival in culture of mutant cells only. Whereas in the male gouty propositus the cell culture was homogenous for the mutant enzyme, in the cell culture from his nongouty mother two cell populations were demonstrated, one normal and the other mutant. The mosaicism in the mother is compatible with X-linkage of the enzyme. From this finding, together with the clinical and biochemical data available, it is concluded that in this family the enzyme mutation is transmitted in a X-linked recessive pattern.

Action of Naja naja and Vipera palestinae venoms on cat brain phospholipids in vitro

Abstract The action in vitro of Naja naja and Vipera palestinae venoms on phospholipids in cat brain slices, homogenates and mitochondria has been studied. Both venoms have no or little phospholipid splitting activity when applied to brain slices. Naja naja venom as well as its electrophoretically separated phopholipase A are able to hydrolyze lecithin, phosphatidyl ethanolamine, phosphatidyl serine and plasmalogen in cat brain homogenates and mitochondria, but Vipera palestinae venom is ineffective.

Preparation of an antivenin against Vipera palestinae venom with high antineurotoxic potency

Abstract A potent antiserum against Vipera palestinae venom was produced in horses, using as antigens whole venom and carboxymethyl cellulose-bound neurotoxin, both admixed with adjuvant. The antiserum contained antibodies to satisfactory titer against both the hemorrhagin and the neurotoxin of the venom.

Airborne allergens and clinical response of asthmatics in Arad, a new town in a desert area in Israel

Abstract A clinical study of patients with intractable asthma coming to the new Judean desert town of Arad was carried out concurrently with an aerobiological survey. Pollen and mold concentrations in the air of Arad were about one third and one half, respectively, of those in the central coastal region of Israel. Excellent to moderate clinical responses to the stay in Arad were observed in 84 per cent of the asthmatic subjects. The moderate reduction of pollen and mold spore content in the air of Arad is not a satisfactory explanation for the beneficial results. The reason for improvement of asthmatics in desert climates in many instances still remains unsolved.

Isolation of three different neurotoxins from indian cobra (Naja naja) venom and the relation of their action to phospholipase a

Abstract Six fractions of the venom of the Indian cobra (Naja naja) were separated by paper electrophoresis of which four (fractions 6, 3, 2 and 1) were toxic in anaesthetized cats or in mice, or in both species. Of the four toxic fractions only fraction 6 contained phospholipase ; it was toxic to cats but not to mice. Fraction 3 was toxic to cats and mice and fractions 1 and 2 were toxic to mice but not to cats. Thus three different neurotoxic fractions were separated. In the anaesthetized cat the intravenous injection of fraction 6 caused the same effect as the injection of whole or boiled venom, i.e., a diphasic circulatory shock—an initial rapid fall in arterial blood pressure followed after partial recovery by a delayed gradual fall—with depression of cerebral cortical activity. The central vasoregulating mechanisms were apparently not affected during the shock since records taken from the cervical sympathetic showed increased activity. Fraction 3 did not produce the initial fall in arterial blood pressure but only the delayed phase of shock. In mice, the toxic effects of an intraperitoneal injection of whole venom resulted in convulsions, excitement, motor impairment and respiratory arrest; the injection of fractions 1 and 2 resulted in apathy, motor depression and convulsions before death, and the injection of fraction 3 in excitement, convulsions, repeated laboured respiration, and curling of the tail.