Presence Of Bivalent Cations Research Articles

Effect of the ionic environment on the molecular structure of bacteriophage SPP1 portal protein.

Bacteriophage SPP1 portal protein is a large cyclical homo-oligomer composed of 13 subunits. The solution structure and assembly behavior of this protein with high-point rotational symmetry was characterized. The purified protein was present as a monodisperse population of 13-mers, named gp6H, at univalent salt concentrations in the hundred millimolar range (>/= 250 mM NaCl) or in the presence of bivalent cations in the millimolar range (>/= 5 mM MgCl2). Gp6H had a slightly higher sedimentation coefficient, a smaller shape-dependent frictional ratio, and a higher rate of intersubunit cross-linking in the presence of magnesium than in its absence. In the absence of bivalent cations and at univalent salt concentrations below 250 mM, the 13-mer molecules dissociated partially into stable monomers, named gp6L. The monomer had a somewhat different shape from the subunit present in the 13-mer, but maintained a defined tertiary structure. The association-dissociation equilibrium was mainly between the monomer and the 13-mer with a minor population of intermediate oligomers. Their interconversion was strongly influenced by the ionic environment. Under physiological conditions, the concentration of Mg2+ found in the Bacillus subtilis cytoplasm (10-50 mM) probably promotes complete association of gp6 into 13-mer rings with a compact conformation.

Characterization of an Isoprene Synthase from Leaves of Quercus petraea (Mattuschka) Liebl.

Abstract:Biogenic emission of isoprene (2‐methyl‐1,3‐butadiene) by many plant species plays an important role in atmospheric chemistry. Its rapid breakdown in the atmosphere substantially affects the oxidation potential of the atmosphere. Leaves of Quercus petraea were found to contain an enzyme which catalyses the conversion of dimethylallyl pyrophosphate (DMAPP) to isoprene. A standard enzyme assay was established and the isoprene synthase activity was characterized in purified leaf extracts. Optimum enzyme activity was observed at pH 8.5. The enzyme had an apparent Km of 0.97 mM for its substrate DMAPP, but isopentenyl pyrophosphate (IPP), the isomeric form of DMAPP, was not converted to isoprene by the enzyme extract. The temperature optimum of the enzyme activity was 35 °C. Isoprene synthase activity was strictly dependent on the presence of bivalent cations, with magnesium being most effective. Molecular weight determination by FPLC revealed the presence of a single protein with a native molecular weight of approximately 90–100 kDa.

Comparison of Enantiomeric and Racemic Monolayers of 2-Hydroxyhexadecanoic Acid by External Infrared Reflection-Absorption Spectroscopy

Surface pressure/area (Π/A) isotherms and infrared reflection-absorption spectra (IRRAS) of racemic and enantiomeric 2-hydroxyhexadecanoic acid (HHDA) Langmuir films showed that the presence of bivalent cations in the aqueous subphase gives rise to considerable compression (Ca 2+ > Pb 2+ ∼ Zn 2+ ) and to increased chiral discrimination (Ca 2+ < Pb 2+ ∼ Zn 2+ )in HHDA monolayers. Although both in the presence of Pb 2+ and Zn 2+ cations the Π/A isotherms of the L-enantiomer exhibit the more condensed characteristics, the IRRAS measurements show that Pb 2+ cations induce, against expectation, heterochiral discrimination in compressed HHDA films, while the presence of Zn 2+ cations leads to preferred homochiral interactions. In the latter two instances, the conformational order of the alkyl chain is nearly independent of the compressional status of the monolayer ; i.e., the optimum order induced by the presence of Pb 2+ and Zn 2+ cations is already attained at very low surface pressures around 1 mN m -1 . The different influence of bivalent cations on chiral recognition is assumed to be caused by different complexes formed by the respective cation and the functional group of the film-forming substances. Hence, in addition to van der Waals and electrostatic interactions as well as hydrogen-bond formation, potential complex formation between bivalent cations and the head group appears to play an important role for heterochiral and homochiral discrimination in chiral Langmuir films.

Interaction of bipyridilium herbicides with model membranes

Divalent cationic bipyridilium derivatives (Paraquat) have been widely used in agriculture; the primary target of these chemicals has been considered to be the phospholipids, and their effects could be modulated by the presence of bivalent cations. A study of paraquat (PQ)-phospholipid (PL), with different charge at pH 7, has been carried out by means of some different chemico-physical techniques. The systems PQ-dipalmitoylphosphatidic acid (DPPA) and PQ-dipalmitoylphosphatidylcholine (DPPC) water suspensions at pH 7 have been investigated. The experimental results demonstrate that the interaction between PQ and PL is mainly electrostatic; PQ strongly binds DPPA, which bears one negative charge at pH 7, but only weakly DPPC. The small changes in the DSC curves of DPPC can be explained by a small penetration into PL bilayer of the hydrophobic tail of PQ molecules. The presence of calcium ions, in an amount sufficient to bind completely the lipid, strongly alters the DPPA-PQ interactions, thus inhibiting the binding of PQ to lipid. On the contrary, the DPPC-PQ interactions are not modified by the presence of calcium ions. The behaviour of PQ is different from that of other polycations as polyamines, due to the steric effects present in the PQ molecule. Our results confirm that the negatively charged PL could be the possible molecular target of PQ. The electrostatic interactions are strongly modulated by the presence of cations with a great affinity for the phosphate group, such as calcium ions.

Glycosphingolipid-Glycosphingolipid Interaction: A Model for a New Type of Cell Recognition System.

Endogenous lectins (including selectins) are expected to define carbohydrate(CHO)-dependent adhesion between a cell showing surface expression of lectin and a different cell expressing the target CHO epitope. This mechanism, however, is apparently not universal because surface expression of lectins is seen only in certain cell types, and the structures defined by known lectins and selectins are highly restricted. In contrast, surface expression of a great number of CHOs [including glycosphingolipids(GSLs)] is known to change dramatically during ontogenesis and oncogenesis, and cell adhesion occurring at defined stages of ontogenesis can be inhibited by specific CHOs or GSLs. Our early studies focused on the mechanism of tight cell adhesion(compaction) of morula-stage embryo cells, as mediated by Lex, and led to the discovery of Lex-Lex interaction in the presence of bivalent cation. Later, more systematic studies on adhesion of various GSLs (incorporated in [14C]cholesterol-liposomes) to GSLs coated on plastic plates showed strong H-H, H-Ley, GM3-Gg3Cer, GM3-LacCer, and sulfatide-GalCer interaction. We also demonstrated (i) specific interaction between GM3-expressing B16 mouse melanoma cells and Gg3Cer-expressing L5178 mouse leukemia cells based on GM3-Gg3Cer interaction, and (ii) adhesion of B16 variants to endothelial cells(ECs) based on GM3-LacCer interaction. Relative degree of GM3 expression in four B16 variants, and degree of adhesion to ECs or LacCer-coated plates, was found to be in the same order as degree of metastatic potential of the B16 variants. Initial adhesion of B16 cells to non-activated ECs is mediated by GM3-LacCer interaction. Experimental data from a dynamic flow adhesion system supported this hypothesis. The GSL-GSL interactions demonstrated in these experimental systems may reflect a generalized phenomenon, i.e., involvement of specific CHO-CHO interaction in the earliest stages of cell-cell recognition and adhesion, which triggers subsequent (and stronger) adhesion events mediated by integrin and immunoglobulin family receptors.

Cell adhesion, spreading, and motility of GM3-expressing cells based on glycolipid-glycolipid interaction.

Cell lines expressing varying levels of ganglioside GM3 at the cell surface show different degrees of adhesion and spreading on solid phase coated with such glycosphingolipids (GSLs) as Gg3 (GalNAc beta 1----4Gal beta 1----4Glc beta 1----1Cer), LacCer (Gal beta 1----4Glc beta 1----1Cer), or Gb4 (GalNAc beta 1----3Gal alpha 1----4Gal beta 1----4Glc beta 1----1Cer) (where Cer is ceramide), which may have structures complementary to GM3, but not on solid phase coated with various other GSLs. The degree of cell adhesion and spreading on Gg3 was correlated with the degree of cell-surface GM3 expression, as defined by reactivity with anti-GM3 monoclonal antibody (mAb) DH2. Only cells with high GM3 expression adhered on solid phase coated with LacCer or Gb4. Adhesion of GM3-expressing cells on Gg3-, LacCer-, and Gb4-coated solid phase is based on interaction of GM3 with Gg3 and, to a lesser extent, with LacCer and Gb4, as demonstrated by: (i) the interaction of the GM3 liposome with solid phase coated with Gg3, LacCer, and Gb4, respectively; (ii) the abolition of cell adhesion on each GSL-coated solid phase by treatment of cells with mAb DH2 or sialidase; and (iii) the inhibition of cell adhesion by treatment of GSL-coated solid phase with mAb specific to each GSL. Sialosyllactosyl-lysyllysine conjugate was bound to Gg3 adsorbed on a C18 silica gel column in the presence of bivalent cation, suggesting that the carbohydrate moiety of GM3 is involved in GM3-Gg3 interaction. Not only the adhesion and spreading of GM3-expressing cells, but also their cell motility was greatly enhanced on Gg3-coated solid phase, as determined by Transwell assay and phagokinetic track assay on a gold sol-coated surface. Spreading and motility of GM3-expressing cells on Gg3-coated solid phase were both inhibited by treatment of cells with mAb DH2 or sialidase. These results provide evidence that not only cell adhesion, but also spreading and motility in these cell lines are controlled by complementary GSL-GSL interaction.

Ultracentrifugation study on interactions among calmodulin, cardiac troponin and tropomyosin-actin complex

In an effort to clarify the regulation of contractions in cardiac muscle, we performed ultracentrifugation studies on the interactions between cardiac troponin and tropomyosin-actin complex in the presence of Ca 2+ or Sr 2+. When troponin C and troponin I were centrifuged with tropomyosin-actin complex, troponin I was not removed from tropomyosin-actin complex in the presence of bivalent-cation. Troponin C was observed to bind very weakly to troponin T-tropomyosin-actin complex in either the presence or absence of bivalent-cation. When troponin C was replaced by calmodulin, troponin I was not removed from tropomyosin-actin complex in the presence of bivalent-cation. Calmodulin bound to the troponin I-troponin T-tropomyosin-actin complex only in the presence of bivalent-cation. These results suggest that the inhibitory action of troponin I is neutralized by troponin C or calmodulin upon binding of bivalent-cation while troponin I binds to tropomyosin-actin complex in cardiac muscle. Therefore cardiac muscle seems to differ from skeletal muscle in regard to regulation of its contraction.

Further Characterization and Immunochemical Studies on the Carbohydrate Specificity of Jackfruit (Artocarpus integrifolia) Lectin

The lectin from jackfruit (Artocarpus integrifolia) seeds has been purified by Rivanol (6,9-diamino-2-ethoxyacridine lactate) treatment. The specific activity, molecular weights of parent lectin and its subunit, its glycoprotein nature, and hemagglutination-inhibition assays suggest that this preparation is identical to that obtained by affinity chromatography on melibiose-agarose adsorbent (Ahmed, H., and Chatterjee, B. P. (1986) in Lectins, Biology, Biochemistry, Clinical Biochemistry (Bøg-Hansen, T. C., and van Driessche, E., eds) Vol. 5, pp. 125-133, Walter de Gruyter, New York). The lectin strongly agglutinates human and several animal erythrocytes. The lectin contains five isolectins of pI values 7.1, 6.85, 5.5, 5.3, and 5.1. It is thermally stable and loses its activity above 75 degrees C. The hemagglutinating activity remains unchanged in the presence of bivalent cations viz., Ca2+, Mg2+, Mn2+, etc. It is a metalloprotein. The lectin retains its activity by dialysis with acetic acid followed by EDTA. It agglutinates Ehrlich ascites cells. Equilibrium dialysis of lectin with melibiose and quenching of fluorescence of 4-methylumbelliferyl-alpha-D-galactopyranoside by the lectin show that homotetrameric jackfruit lectin has two sugar-binding sites. The lectin precipitates well several galactomannans and glycoproteins having terminal D-Gal-alpha-(1----6)- or D-Gal-beta-(1----3)-D-GalNAc residues. It hardly or does not precipitate polysaccharides having terminal D-Gal-alpha-(1----3) residues. Quantitative precipitin-inhibition studies using various haptens suggest that the -OCH2- group at C-1 and -OH groups at C-4 and partially at C-6 in the alpha-glycoside of D-galactose configuration are important for lectin-sugar interaction.

Interaction of calmodulin with troponin I and the troponin-tropomyosin-actin complex. Effect of Ca2+ and Sr2+ ions.

In an effort to elucidate the mechanism of calmodulin regulation of muscle contraction, we investigated the interaction between calmodulin and troponin components in the presence of Ca2+ or Sr2+ by the use of ultracentrifugation methods and polyacrylamide-gel electrophoresis. Skeletal-muscle troponin C bound to troponin I and dissociated it from the tropomyosin-actin complex in the presence of Ca2+ or Sr2+. When troponin T was absent, calmodulin bound to troponin I and dissociated it from the tropomyosin-actin complex in the presence of Ca2+ or Sr2+. When troponin T was present, calmodulin hardly bound to troponin I even in the presence of bivalent cations. Trifluoperazine, a calmodulin antagonist, inhibited the bivalent-cation-dependent interaction between calmodulin and troponin I. Calmodulin migrated more slowly in the presence of Sr2+ than it did in the presence of EGTA but faster than it did in the presence of Ca2+ on polyacrylamide-gel electrophoresis under non-denaturing conditions. It is concluded that troponin T is not required in the calmodulin regulation of muscle contraction because troponin T inhibits the bivalent-cation-dependent interaction between calmodulin and troponin I and because calmodulin binds to troponin I and dissociates it from the tropomyosin-actin complex in a bivalent-cation-dependent manner. Sr2+-induced exposure of the hydrophobic region enables calmodulin to bind to troponin I, as is the case with Ca2+.

Cystine transport in purified rat liver lysosomes.

Amino acid efflux from highly purified rat liver lysosomes exposed to the methyl ester derivatives of leucine, methionine, tyrosine and cystine was examined. The lysosomal efflux of leucine, methionine and tyrosine was unaffected by the presence of MgATP, whereas cystine efflux was stimulated by MgATP. Exposure of lysosomes to 2 mM-MgATP resulted in lysosomal acidification and a 0.5 pH unit increase in the lysosomal pH gradient through the action of a proton-pumping ATPase. Cystine efflux was also stimulated when the lysosomal proton gradient was increased through changes in buffer pH. Decreasing the lysosomal proton gradient with ionophores resulted in diminished cystine efflux. Bivalent cations had no effect on the lysosomal efflux of leucine, methionine and tyrosine. However, cystine efflux was stimulated by the presence of bivalent cations even when the lysosomal proton gradient was minimized. Cation-stimulated cystine efflux was inhibited by the presence of the calcium ionophore A23187, which altered the lysosomal membrane potential. Cystine efflux from lysosomes appears to be uniquely dependent on pH gradients and cation concentrations.

Isolation of complement-fragment-iC3b-binding proteins by affinity chromatography. The identification of p150,95 as an iC3b-binding protein.

The proteins from labelled human spleen membranes and polymorphonuclear leucocytes which bind to the iC3b fragment of complement component C3 were prepared by iC3b-Sepharose chromatography in the presence of bivalent cations. Complement receptor type 3(CR3) was eluted from iC3b-Sepharose by removal of bivalent cations. Complement receptors type 1 and 2 (present in spleen but not in polymorphonuclear leucocytes) were sequentially eluted by an NaCl gradient. An additional protein of Mr 135 000 was eluted from iC3b-Sepharose under the same conditions as those used to elute CR3. Preabsorption of the starting material on an anti-(CR3 beta-subunit) antibody column before iC3b-Sepharose chromatography removed the alpha- and beta-chains of CR3 and the 135 000-Mr protein. Preabsorption with iC3b-Sepharose before the anti-(CR3 beta-subunit) antibody column showed that iC3b binds CR3 and p150,95, the smallest member of the group of three homologous proteins that share the same beta-subunit.

Fibrinogen interaction with platelet receptors.

In summary: Incubation of platelets with ADP or proteolytic enzymes (chymotrypsin or pronase) results in an exposure of two classes of specific binding sites on platelet surface: low and high affinity fibrinogen receptors. Fibrinogen interaction with these receptors results in platelet aggregation. High affinity fibrinogen receptors are not exposed on thrombasthenic platelets stimulated by ADP but are rendered available on chymotrypsin-treated thrombasthenic platelets; low affinity receptors cannot be exposed by ADP or chymotrypsin on these platelets. Availability of high affinity fibrinogen receptors on thrombasthenic platelets may depend on the residual glycoprotein IIIa. Fibrinogen receptors appear to be associated with glycoproteins IIb, IIIa and a 66,000 Mr platelet membrane component that is exposed during proteolysis of platelet membranes. Some of the platelet-binding sites on the fibrinogen molecule appear to be associated with the COOH-terminal portion of the gamma chain (gamma 374-411). Additional binding sites may also be located in the COOH-terminal portion of the A alpha chain. The conformation of the fibrinogen molecule may be important in its interaction with platelets. Platelet aggregation may result from bridging platelets by fibrinogen molecule in the presence of bivalent cations. In conclusion, platelet interaction with fibrinogen is a complex process involving different binding sites of the fibrinogen molecule. Our own data and review of literature suggest that platelet-interaction with fibrinogen is of major significance in hemostasis.

Phase behaviour in monolayers and in water dispersions of mixtures of dimannosyl diacylglycerol with phosphatidylglycerol Effect of monovalent and bivalent cations

Mixtures of dimannosyl diacylglycerol, extracted from the membrane of Micrococcus luteus, with synthetic dipalmitoyl phosphatidylglycerol or with samples of phosphatidylglycerol and phosphatidylinositol, extracted from the same bacterium, have been studied. Through a monolayer (π, Δν) study and from fluorescence polarization data relative to diphenylhexatriene embedded in vesicles of the mixed lipids, it is shown that the glycolipid interacts with the phospholipids. These interactions are independent of the structure and physical state of the phospholipid acyl chains, of the lipid molecular packing and of the nature of the cations (monovalent, bivalent) present in the aqueous phase. No phase separation was detected, either in monolayers or in water dispersions. Furthermore, the data presented demonstrated a marked influence of the glycolipid on the phase behaviour of phosphatidylglycerol, both in the presence of monovalent (Na +,K +) and bivalent (Ca 2+, Mg 2+ cations. This point is of particular interest with regard to the highly rigid phase this phospholipid is known to assume in the presence of bivalent cations. It is then suggested that the glycolipid could act as a regulator of the membrane fluidity by preventing a too high rigidity of the lipid phase when bivalent cations are present at the membrane surface.

Sorption and Binding Mechanism of Polysaccharide Cleaving Soil Enzymes by Clay Minerals

AbstractAnalyses of the sorption of five polysaccharide cleaving soil enzymes by Na‐homoionic clay minerals revealed a dependency on the cation exchange capacity of the clays: montmorillonite displayed the highest sorbing capacity, followed by palygorskite and kaolinite. Variation of the experimental conditions using cellulase and montmorillonite showed a maximum sorption at pH 4.8 and temperatures between 25°C and 45°C. Urea had no effect on the sorption, whereas humic acids and acetylation of enzymes lead to a decrease. No sorption was observed in the presence of bivalent cations. A discussion of possible binding mechanisms lead to the conclusion that interactions can be ascribed to van der Waals forces rather than to ionic reactions. It is assumed that the enzymes penetrate into the interlayers of montmorillonite, but not of palygorskite and kaolinite.

Fluorescent photoaffinity labeling of F 1 ATPase from Micrococcus luteus with 8-azido-1, N6-etheno-adenosine 5′-triphosphate

A fluorescent photoaffinity label—8-azido-1- N 6-etheno-adenosine 5′-triphosphate (8-N 3ε ATP)—for ATP-binding proteins has been synthesized. The effectiveness of the label is demonstrated with F 1ATPase from Micrococcus luteus. 8-N 3ε ATP is a substrate for the enzyme in the presence of bivalent cations. Ultraviolet irradiation of F 1ATPase in the presence of the label and Mg 2+ ions inhibits the enzyme irreversibly. The fluorescent label is bound preferentially to the β subunit of the enzyme. Labeling and inactivation are decreased by protection with ATP or ADP.

Polynucleotides adsorb on mitochondrial and model lipid membranes in the presence of bivalent cations

Transfer of polynucleotides across the membrane was demonstrated for prokaryotic [l] as well as for eukaryotic cells [2] . This process involves adsorption of polynucleotides on the cell surface, penetration and release into the cell. The mechanism of crossing the hydrophobic barrier formed by protein-lipid membrane by large hydrophilic molecule is unknown. In particular, the nature of bonds which provide adsorption of polynucleotides on the membranes is unknown. Investigation of this problem with cells is difficult due to the presence of more or less expressed cell wall. Mitochondria can be used as convenient model objects to this end because their outside surface is a ‘pure’ protein-lipid membrane. There exist some experimental data suggesting that RNA can penetrate the mitochondrial membrane. Polynucleotides added to mitochondria stimulate protein synthesis by mitochondrial ribosomes insensitive to exogenous ribonuclease [3-61. Mitochondria contain tRNAs which are coded by the nuclear genome and therefore have to be transferred into mitochondria from the cytoplasm [7] . We demonstrate here that polynucleotides are adsorbed by mitochondrial membranes as well as by liposomes formed either from total mitochondrial lipids or from phosphatidylcholine. The dependence of this adsorption on the presence of Mg2+ permits us to suggest that this interaction is due to action of bivalent cations as crosslinks between phosphate residues of polynucleotides and phosphate residues of the membranes.

Kinetic properties of cytosol 5′-nucleotidase from chicken liver

A highly purified preparation of cytosol 5′-nucleotidase (5′-ribonucleotide phosphohydrolase, EC 3.1.3.5) from chicken liver was effectively activated by ATP and inhibited by P i. When AMP was used as substrate, the enzyme displayed sigmoidal kinetics. When either IMP, GMP, UMP or CMP was used as substrate, the substrate saturation curve was slightly sigmoidal or hyperbolic. In the presence of 10 mM ATP, the substrate saturation curves for all substrates tested were hyperbolic, whereas P i increased the sigmoidicity of the saturation curves. The enzyme had much higher affinities for IMP and GMP than for AMP, UMP and CMP. ATP decreased the s 0.5, whereas P i increased the s 0.5 for all the substrates tested. Inhibition by P i was removed by ATP, and activation by ATP was removed by P i. V of the enzyme was determined to be in the same order of the magnitude for all the substrates tested. The hydrolysis of GMP was inhibited competitively by the other 5′-nucleotides. AMP at low concentration had a stimulatory effect on the hydrolysis of GMP. The enzyme activity was absolutely dependent on the presence of bivalent cations. Increasing concentration of MgCl 2 increased the V and affinity of the enzyme for AMP and vice versa. ATP protected the enzyme against the inactivation by heat or trypsin digestion. It seems likely that this enzyme is an allosteric protein regulated by various ligands through conformational changes.

8-Azido-adenosine 5'-triphosphate as a photoaffinity label for bacterial F1 ATPase.

1. 8-Azido-adenosine 5'-triphosphate (n83ATP) is a suitable photoaffinity label for F1 ATPase from Micrococcus luteus. The nucleotide is a substrate in the presence of bivalent cations and inhibits the enzyme irreversibly upon irradiation with ultraviolet light above 300 nm. 2. More than 80% of the label is covalently bound to the beta subunits in the presence of bivalent cations. Labeling and inactivation is decreased by protection with ADP, ATP or adenyl-5'-yl imidodiphosphate. To a much smaller degree the alpha subunits also become labeled. 3. n83AMP does not specifically bind to the beta subunits upon irradiation. Like n83ATP and n83ADP, it also labels the alpha subunits to a small extent. 4. The F1 ATPase is inactivated after a single beta subunit per F1 complex has become labeled. A cooperativity of the beta subunits carrying nucleotide binding sites is suggested.

Prevention of hemolysis by bivalent metal ions during virus-induced fusion of erythrocytes with ehrlich ascites tumor cells

Chicken erythrocytes have recently been fused to form homopolykaryons with Sendai virus in the presence of bivalent cations [ 1,2] or with the aid of lysolecithin [3]. Human erythrocytes could also be fused with each other under similar conditions [4,5] . When adult chicken erythrocytes were fused with other cells only the nuclei of the erythrocyte were incorporated into the heterokaryon while the cytoplasm was lost by lysis [6] . It seemed of considerable potential interest to form heterokaryons of erythrocytes with other cells without hemolysis since this would make it possible to study the effects of erythrocyte cytoplasm on the activity of the nucleus and cytoplasm of other cell types. The aim of the present investigation was to find conditions for fusing erythrocytes with other cells without the loss of erythrocyte cytoplasm. This paper shows that the techniques developed for the formation of homopolykaryons [2,4] may be applied with slight modification to the fusion of chicken and human erythrocytes with other cells without loss of erythrocyte cytoplasm.

Non enzymic formation of nerolidol from farnesyl pyrophosphate in the presence of bivalent cations

1- 3H Farnesyl pyrophosphate is hydrolyzed non enzymically at neutral or alkaline pH in the presence of Mg 2+ or Mn 2+. The pattern of product formation differs for these two ions. In the presence of Mn 2+, nerolidol is practically the only reaction product, whereas in the presence of Mg 2+ the hydrolysis products are nerolidol and farnesols. The effect of Mg 2+ is pH dependent. The formation of nerolidol from mevalonic acid or other precursors of isoprenoids may thus be explained as a non enzymic reaction of farnesyl pyrophosphate.