Molecular organization of gap junctions

Highly purified gap junction fractions from heart and liver contain a single major protein component. The proteins isolated from different organs have apparent molecular weights of 26,000-30,000. Peptide mapping and partial sequencing show close homology of the hepatic junctional protein of different species. In contrast, no homologies can be detected when polypeptides from different tissues of the rat were compared by peptide mapping. Preliminary results from partial sequencing, however, show that the amino terminal regions of the liver and heart proteins are related to one another. Sequencing has not yet revealed any such homologies between the lens and the other junction proteins.     

Integrated view and comparative analysis of baseline protein expression in mouse and rat tissues

The increasingly large amount of proteomics data in the public domain enables, among other applications, the combined analyses of datasets to create comparative protein expression maps covering different organisms and different biological conditions. Here we have reanalysed public proteomics datasets from mouse and rat tissues (14 and 9 datasets, respectively), to assess baseline protein abundance. Overall, the aggregated dataset contained 23 individual datasets, including a total of 211 samples coming from 34 different tissues across 14 organs, comprising 9 mouse and 3 rat strains, respectively.In all cases, we studied the distribution of canonical proteins between the different organs. The number of canonical proteins per dataset ranged from 273 (tendon) and 9,715 (liver) in mouse, and from 101 (tendon) and 6,130 (kidney) in rat. Then, we studied how protein abundances compared across different datasets and organs for both species. As a key point we carried out a comparative analysis of protein expression between mouse, rat and human tissues. We observed a high level of correlation of protein expression among orthologs between all three species in brain, kidney, heart and liver samples, whereas the correlation of protein expression was generally slightly lower between organs within the same species. Protein expression results have been integrated into the resource Expression Atlas for widespread dissemination.     

Prediction of thermostability from amino acid attributes by combination of clustering with attribute weighting: a new vista in engineering enzymes

The engineering of thermostable enzymes is receiving increased attention. The paper, detergent, and biofuel industries, in particular, seek to use environmentally friendly enzymes instead of toxic chlorine chemicals. Enzymes typically function at temperatures below 60°C and denature if exposed to higher temperatures. In contrast, a small portion of enzymes can withstand higher temperatures as a result of various structural adaptations. Understanding the protein attributes that are involved in this adaptation is the first step toward engineering thermostable enzymes. We employed various supervised and unsupervised machine learning algorithms as well as attribute weighting approaches to find amino acid composition attributes that contribute to enzyme thermostability. Specifically, we compared two groups of enzymes: mesostable and thermostable enzymes. Furthermore, a combination of attribute weighting with supervised and unsupervised clustering algorithms was used for prediction and modelling of protein thermostability from amino acid composition properties. Mining a large number of protein sequences (2090) through a variety of machine learning algorithms, which were based on the analysis of more than 800 amino acid attributes, increased the accuracy of this study. Moreover, these models were successful in predicting thermostability from the primary structure of proteins. The results showed that expectation maximization clustering in combination with uncertainly and correlation attribute weighting algorithms can effectively (100%) classify thermostable and mesostable proteins. Seventy per cent of the weighting methods selected Gln content and frequency of hydrophilic residues as the most important protein attributes. On the dipeptide level, the frequency of Asn-Glu was the key factor in distinguishing mesostable from thermostable enzymes. This study demonstrates the feasibility of predicting thermostability irrespective of sequence similarity and will serve as a basis for engineering thermostable enzymes in the laboratory.     

Paradoxical relationship between protein content and nucleolar activity in mammalian cardiomyocytes.

It was recently demonstrated that polyploidization of the avian myocardium is associated with a reduction of cardiac aerobic capacity evaluated by the heart mass to body mass ratio (heart index). To investigate possible cellular correlates of polyploidization, the protein content and nucleolar activity per cell and per genome were examined by image cytometry in 21 mammalian species, differing in the degree of heart polyploidization and heart index. We found that average cardiomyocyte ploidy level correlates negatively with the animal heart index (r = -0.75, p < 10(-4)), i.e., the large heart of athletic mammals is polyploidized to a lesser degree than the relatively smaller heart of sedentary species, which confirms the picture observed in birds. The protein content per genome decreased with the elevation of cardiomyocyte ploidy level. This inverse correlation was especially pronounced with the removed effect of body mass (r = -0.79, p < 10(-4)). Surprisingly, these changes were accompanied by the increase of nucleolar activity per genome (r = 0.61, p < 10(-3)). In the two species, for which the microarray gene expression data were available (human and mouse), this increase was paralleled by the elevated expression of ribosomal protein genes (but there was no increase in the expression of tissue-specific genes). Thus, in the polyploid cardiomyocytes there is a misbalance between protein content per genome and ribosome biogenesis. The reduction of protein content (per genome) of polyploid cardio my ocytes should further curtail heart functionality (in addition to reduction of heart index), because it is known that cardio myocyte protein content consists of more than 90% contractile proteins. This finding makes doubtful a widespread notion that polyploidization is necessary for cell function. Because somatic polyploidization is associated with stressful conditions and impaired energetics, we suppose that additional genomes can serve for cell regeneration and as a defense against oxidative damage in the organs that work at the limit of their metabolic capacity.     

Cyclic nucleotides in the dynamic development of shock caused by the murine toxin of Yersinia pestis

The authors have studied the effect of Y. pestis "mouse" toxin (LD50), injected intravenously to rats, on cAMP and cGMP content in the tissues of different organs (the lungs, liver, heart, spleen, kidneys, small intestine) and in the blood in the course of the development of toxinfection shock. The effect of Y. pestis "mouse" toxin on cyclic nucleotide content in the organs of experimental animals is determined by the sum of oppositely directed effects produced by the thermostable and thermolabile fractions of the toxin. Its thermostable fraction, when introduced in the dose used in the experiments, did not kill the animals. The most pronounced changes in the cyclic nucleotide content have been detected in the lungs which appear to be the main target organ for Y. pestis "mouse" toxin.     

Reconstitution of hormone-sensitive adenylate cyclase activity with resolved components of the enzyme.

Adenylate cyclase can be resolved into at least two proteins, a thermolabile, N-ethylmaleimide-sensitive component and a second protein (or proteins) that is more stable to either of these treatments. Neither component by itself catalyzes the formation of cyclic AMP using MgATP as substrate. However, mixture of the two reconstitutes MgATP-dependent fluoride- and guanyl-5'-yl imidodiphosphate (Gpp(NH)p)-stimulatable adenylate cyclase activity. The more stable component can be resolved from the first in various tissues or cultured cells by treatment of membrnes or detergent extracts with heat or N-ethylmaleimide. The two proteins have also been resolved genetically in two clonal cell lines that are deficient in adenylate cyclase activity. An adenylate cyclase-deficient variant of the S49 lymphoma cell (AC-) contains only the thermolabile activity, while the activity of the more stable protein is found in a complementary hepatoma cell line (HC-1). In addition, AC-S49 cell plasma membranes contain MnATP-dependent adenylate cyclase activity. The protein that catalyzes this reaction appears to be the same as that which can combine with the thermostable component to reconstitute Mg2+-dependent enzyme activity because both activities co-fractionate by gel exclusion chromatography and sucrose density gradient centrifugation, both activities have identical denaturation kinetics at 30 degrees C, and both activities are stabilized at 30 degrees C and labilized at 0 degree C by various nucleotides and divalent cations with similar specificity. It is thus hypothesized that the thermolabile factor is the catalytic subunit of the physiological adenylate cyclase and that the Mn2+-dependent activity is a nonphysiological expression of the catalytic protein. The thermostable moiety of the enzyme, which is proposed to serve a regulatory function, appears to consist of two functional components, based upon differential thermal lability of its ability to reconstitute hormone-, NaF-, or Gpp(NH)p-stimulated adenylate cyclase activity. These components have not, however, been physically separated. The thermolabile and thermostable components can interact in detergent solution or in a suitable membrane. Mixing of the detergent-solubilized regulatory component with AC-membranes that contain only the catalytic protein and beta-adrenergic receptors reconstitutes catecholamine-stimulatable adenylate cyclase activity; however, addition of the catalytic protein to membranes that contain receptor and the regulatory component yields MgATP-dependent enzymatic activity that is unresponsive to hormone.     

Enzyme thermoinactivation in anhydrous organic solvents

Three unrelated enzymes (ribonuclease, chymotrypsin, and lysozyme) display markedly enhanced thermostability in anhydrous organic solvents compared to that in aqueous solution. At 110-145 degrees C in nonaqueous media all three enzymes inactivate due to heat-induced protein aggregation, as determined by gel filtration chromatography. Using bovine pancreatic ribonuclease A as a model, it has been established that enzymes are much more thermostable in hydrophobic solvents (shown to be essentially inert with respect to their interaction with the protein) than in hydrophilic ones (shown to strip water from the enzyme). The heat-induced aggregates of ribonuclease were characterized as both physically associated and chemically crosslinked protein agglomerates, with the latter being in part due to transamidation and intermolecular disulfide interchange reactions. The thermal denaturation of ribonuclease in neat organic solvents has been examined by means of differential scanning calorimetry. In hydrophobic solvents, the enzyme exhibits greatly enhanced thermal denaturation temperatures (T(m) values as high as 124 degrees C) compared to aqueous solution. The thermostability of ribonuclease towards heat-induced denaturation and aggregation decreases as the water content of the protein powder increases. The experimental data obtained suggest that enzymes are extremely thermostable in anhydrous organic solvents due to their conformational rigidity in the dehydrated state and their resistance to nearly all the covalent reactions causing irreversible thermoinactivation of enzymes in aqueous solution.     

Biliary secretion of phosphatidylcholine and its molecular species in cholecystectomized T-tube patients: effects of bile acid hydrophilicity

The aim of the present study was to establish whether the oral administration of bile acids with different hydrophilic properties affects the amount of phosphatidylcholine as well as the pattern of PC molecular species secreted in bile. We studied the biliary output of total and individual PC species in cholecystectomized T-tube patients, with a total biliary outflow, after oral administration of 750 mg of ursodeoxycholate (3 patients) or deoxycholate (3 patients). The latter experiments were repeated after 3 days of taurine supplementation (1500 mg daily) in order to increase, by means of the tauro-conjugation, the hydrophilicity of the secreted BA. A linear function was observed, during all the studies, between BA and PC biliary secretion, but the amount of PC secreted per mole of BA was higher for the less hydrophilic BA, such as deoxycholate, than for the more hydrophilic ursodeoxycholate or during deoxycholate plus taurine experiments. With regard to the pattern of PC molecular species, we observed no changes after administration of ursodeoxycholate. An increase in the secretion of the major polyenoic species (i.e., 16:0-18:2 and 16:0-20:4), with respect to the secretion of the monoenoic, was revealed during deoxycholate experiments. Conversely, during the deoxycholate plus taurine experiments, the secretion of the major monoenoic PC species (i.e., 16:0-18:1) increased more than that of the polyenoic species. We suggest that the observed modifications of the pattern of PC molecular species, secreted in bile, represent the result of a physicochemical effect of BA on liver membranes.     

Functional and expression pattern analysis of chemosensory proteins expressed in antennae and pheromonal gland of Mamestra brassicae

Sequences coding for chemosensory proteins (CSP) CSPMbraA and CSPMbraB, soluble proteins of low mol. wt, have been amplified using polymerase chain reaction on antennal and pheromonal gland complementary DNAs. On the basis of their sequences, these proteins could be classed in the 'OS-D like' protein family whose first member was described in Drosophila, and that includes proteins characterized in chemosensory organs of many insect phylla, including our recent identification in Mamestra brassicae proboscis. Binding assays have shown that these proteins bind the pheromonal component (Z)-11-hexadecenyl-1-acetate (Z11-16:Ac) as well as (Z)-11-octadecenyl-1-acetate (Z11-18:Ac), an other putative component of the M. brassicae pheromonal blend. Furthermore, binding with fatty acids, but not with progesterone that is a structurally unrelated compound, leads to the hypothesis that the odorant-binding capability of the MbraCSPs may be restricted to fatty acids and/or to 16-18 carbon backbone skeletons. Thus, these proteins do not show the same highly binding specificity as the pheromone-binding proteins do. The CSP-related proteins appear homologous based on sequence identity, conserved cysteine residues and general patterns of expression. However, phylogenetic analyses suggest the presence of multiple classes of CSP within a given species and possible diversification of CSPs within different orders. This diversity perhaps contributes to the many CSP functions proposed in the literature. In M. brassicae, we localized the CSPMbraA expression to the sensilla trichodea, devoted to pheromone reception, suggesting a role in the chemosensory pathway. However, we also localized such proteins in the pheromonal gland, devoid of any chemosensory structure. This suggests that the M. brassicae CSP could be involved in transport of hydrophobic molecules through different aqueous media, such as the sensillar lymph, as well as the pheromonal gland cytosol.     

Human Platelet Phenol Sulfotransferase: Partial Purification and Detection of Two Forms of the Enzyme

To begin to study the usefulness of platelet phenol sulfotransferase (PST) as a possible measure of the enzyme activity in other organs such as the brain, we purified human platelet PST 36-120-fold. Activity toward 3-methoxy-4-hydroxyphenylglycol (MHPG), dopamine, 5-hydroxytryptamine (5-HT), and phenol eluted in the same Sephadex G-100 and Affi-Gel Blue column fractions. Specific activities of the enzyme with MHPG, dopamine, 5-HT, and phenol as substrates were 1198, 1068, 401, and 408 units/mg protein, respectively. Optimal assay conditions were established for each substrate. Apparent Km values were 598 microM, 21 microM, 19 microM, and 500 microM for MHPG, dopamine, phenol, and 5-HT, respectively. Apparent Km values for 3'-phosphoadenosine-5'-phosphosulfate (PAPS) with the same four substrates ranged from 0.11 to 0.25 microM. The pH optima were 6.3 for phenol, 6.8 for dopamine, and 7.0 for MHPG and 5-HT. An additional pH optimum at 8.6 was present for 5-HT. A thermolabile form of the enzyme measured with dopamine and 5-HT, as well as a thermostable form measured with phenol, were present. Dichloronitrophenol (10(-5) M) noncompetitively inhibited the thermostable enzyme activity by 96% but decreased the thermolabile activity by only 36%. These studies provide the basis for a more accurate comparison of human platelet PST with the enzyme in the human brain and in other tissues.     

Profound biopterin oxidation and protein tyrosine nitration in tissues of ApoE-null mice on an atherogenic diet: contribution of inducible nitric oxide synthase

Diminished nitric oxide (NO) bioactivity and enhanced peroxynitrite formation have been implicated as major contributors to atherosclerotic vascular dysfunctions. Hallmark reactions of peroxynitrite include the accumulation of 3-nitrotyrosine (3-NT) in proteins and oxidation of the NO synthase (NOS) cofactor, tetrahydrobiopterin (BH(4)). The present study sought to 1) quantify the extent to which 3-NT accumulates and BH(4) becomes oxidized in organs of apolipoprotein E-deficient (ApoE(-/-)) atherosclerotic mice and 2) determine the specific contribution of inducible NOS (iNOS) to these processes. Whereas protein 3-NT and oxidized BH(4) were undetected or near the detection limit in heart, lung, and kidney of 3-wk-old ApoE(-/-) mice or ApoE(-/-) mice fed a regular chow diet for 24 wk, robust accumulation was evident after 24 wk on a Western (atherogenic) diet. Since 3-NT accumulation was diminished 3- to 20-fold in heart, lung, and liver in ApoE(-/-) mice missing iNOS, iNOS-derived species are involved in this reaction. In contrast, iNOS-derived species did not contribute to elevated protein 3-NT formation in kidney or brain. iNOS deletion also afforded marked protection against BH(4) oxidation in heart, lung, and kidney of atherogenic ApoE(-/-) mice but not in brain or liver. These findings demonstrate that iNOS-derived species are increased during atherogenesis in ApoE(-/-) mice and that these species differentially contribute to protein 3-NT accumulation and BH(4) oxidation in a tissue-selective manner. Since BH(4) oxidation can switch the predominant NOS product from NO to superoxide, we predict that progressive NOS uncoupling is likely to drive atherogenic vascular dysfunctions.     

The subcellular location of isozymes of NADP-isocitrate dehydrogenase in tissues from pig, ox and rat

Antibodies against purified NADP-isocitrate dehydrogenase from pig liver cytosol and pig heart were raised in rabbits. The purified enzymes from these sources are different proteins, as demonstrated by differences in electrophoretic mobility and absence of crossreactivity by immunotitration and immunodiffusion. The NADP-isocitrate dehydrogenase in the soluble supernatant homogenate fraction from pig liver, kidney cortex, brain and erythrocyte hemolyzate was identical with the purified enzyme from pig liver cytosol, as determined by electrophoretic mobility and immunological techniques. The enzyme in extracts of mitochondria from pig heart, kidney, liver and brain was identical with the purified pig heart enzyme by the same criteria. However, the 'mitochondrial' isozyme was the major component also in the soluble supernatant fraction of pig heart homogenate. The 'cytosolic' isozyme accounted for only 1-2% of total NADP-isocitrate dehydrogenase in pig heart, as determined by separation of the isozymes with agarose gel electrophoresis and immunotitration. The mitochondrial isozyme was also the predominant NADP-isocitrate dehydrogenase in porcine skeletal muscle. The ratio of cytosolic/mitochondrial isozyme for porcine whole tissue extract, determined by immunotitration, was about 2 for liver and 1 for kidney cortex and brain. The distribution of isozymes in cell homogenate fractions from ox and rat tissues corresponded to that observed in organs of porcine origin. The mitochondrial and cytosolic isozymes from ox and rat tissues exhibited crossreactivity with the antibodies against the pig heart and pig liver cytosol enzyme, respectively, and the electrophoretic migration patterns were similar qualitatively to those found for the isozymes in porcine tissues. Nevertheless, there were species specific differences in the characteristics of each of the corresponding isozymes. NAD-isocitrate dehydrogenase was not inhibited by the antibodies, confirming that the protein is distinct from that of either isozyme of NADP-isocitrate dehydrogenase.     

Respiratory organ lipids in fishes and mammals. A model representation of the area of the lipid component]

Studies have been made on lipid composition of the gills in 19 species of fishes and of the lungs in 8 mammalian species. It was shown that the arbitrary "unit fragment" of the lipid component of the respiratory organs in all the investigated animals exhibits similar qualitative composition, but contains different quantity of lipid molecules, i. e. approximately 19 in fishes and 42 in mammals. Theoretical conformational analysis revealed predominant conformations of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, sphingomyelin and cholesterol; projections of these molecules on the surface which is parallel to membrane surface were composed. It was shown that projectional areas for the main phospholipid molecules differ only by 2-3%. These data indicate that the surface of a model of the lipid component in the membranes of respiratory organs in mammals is twice larger than in fishes. These differences presumably account for more effective oxygen transfer in mammals.     

Fatty acid binding proteins from different tissues show distinct patterns of fatty acid interactions

Fatty acid binding proteins (FABP) form a family of proteins displaying tissue-specific expression. These proteins are involved in fatty acid (FA) transport and metabolism by mechanisms that also appear to be tissue-specific. Cellular retinoid binding proteins are related proteins with unknown roles in FA transport and metabolism. To better understand the origin of these tissue-specific differences we report new measurements, using the acrylodated intestinal fatty acid binding protein (ADIFAB) method, of the binding of fatty acids (FA) to human fatty acid binding proteins (FABP) from brain, heart, intestine, liver, and myelin. We also measured binding of FA to a retinoic acid (CRABP-I) and a retinol (CRBP-II) binding protein and we have extended to 19 different FA our characterization of the FA-ADIFAB and FA-rat intestinal FABP interactions. These studies extend our previous analyses of human FABP from adipocyte and rat FABPs from heart, intestine, and liver. Binding affinities varied according to the order brain approximately myelin approximately heart > liver > intestine > CRABP > CRBP. In contrast to previous studies, no protein revealed a high degree of selectivity for particular FA. The results indicate that FA solubility (hydrophobicity) plays a major role in governing binding affinities; affinities tend to increase with increasing hydrophobicity (decreasing solubility) of the FA. However, our results also reveal that, with the exception of the intestinal protein, FABPs exhibit an additional attractive interaction for unsaturated FA that partially compensates for their trend toward lower affinities due to their higher aqueous solubilities. Thermodynamic potentials were determined for oleate and arachidonate binding to a subset of the FABP and retinoid binding proteins. FA binding to all FABPs was enthalpically driven. The DeltaH degrees values for paralogous FABPs, proteins from the same species but different tissues, reveal an exceptionally wide range of values, from -22 kcal/mol (myelin) to -7 kcal/mol (adipocyte). For orthologous FABPs from the same tissue but different species, DeltaH degrees values were similar. In contrast to the enthalpic dominance of FA binding to FABP, binding of FA to CRABP-I was entropically driven. This is consistent with the notion that FA specificity for FABP is determined by the enthalpy of binding. Proteins from different tissues also revealed considerable heterogeneity in heat capacity changes upon FA binding, DeltaC(p) values ranged between 0 and -1.3 kcal mol(-1) K(-1). The results demonstrate that thermodynamic parameters are quite different for paralogous but are quite similar for orthologous FABP, suggesting tissue-specific differences in FABP function that may be conserved across species.     

Chemical screening of an inhibitor for gibberellin receptors based on a yeast two-hybrid system

We applied a yeast two-hybrid (Y2H) system to the high-throughput monitoring of two proteins’ interaction, a receptor for phytohormone gibberellin (GA) and its direct signal transducer DELLA. With this system, we screened inhibitors to the interaction. As a result, we discovered a chemical, 3-(2-thienylsulfonyl)pyrazine-2-carbonitrile (TSPC), and we confirmed that TSPC is an inhibitor for GA perception by in vitro and in planta evaluations.     

Similar nature of inhibition of mitochondrial respiration of heart tissue and malignant cells by methylglyoxal. A vital clue to understand the biochemical basis of malignancy

The effect of methylglyoxal on the oxygen consumption of mitochondria of heart and of several other organs of normal animals of different species has been tested. The results indicate that methylglyoxal (3.5 mM) strongly inhibits ADP-stimulated -oxoglutarate and malate plus pyruvate-dependent respiration of exclusively heart mitochondria of normal animals of different species. Whereas, with the same substrates, but at a higher concentration of methylglyoxal (7.5 mM), the respiration of mitochondria of other organs of normal animals is not inhibited. Methylglyoxal also inhibits the respiration of slices of rat and toad hearts. But this inhibition is less pronounced. However, methylglyoxal (15 mM) fails to have any effect on perfused toad heart. Using rat heart mitochondria as a model, the effect of methylglyoxal on the oxygen consumption was also tested with different respiratory substrates, electron donors at different segments of the mitochondrial respiratory chain and site-spe inhibitors to identify the specific respiratory complex which might be involved in the inhibitory effect of methylglyoxal. The results strongly suggest that methylglyoxal inhibits the electron flow through complex I of rat heart mitochondrial respiratory chain. Moreover, lactaldehyde (0.6 mM), a catabolite of methylglyoxal, can exert a protective effect on the inhibition of rat heart mitochondrial respiration by methylglyoxal (2.5 mM). The effect of methylglyoxal on heart mitochondria as described in the present paper is strikingly similar to the results of our previous work with mitochondria of Ehrlich ascites carcinoma cells and leukemic leukocytes. We have recently proposed a new hypothesis on cancer which suggests that excessive ATP formation in cells may lead to malignancy. The above mentioned similarity apparently provides a solid experimental foundation for the proposed hypothesis which has been discussed.     

Polymorphism of Pseudocholinesterase in Torpedo marmorata Tissues: Comparative Study of the Catalytic and Molecular Properties of this Enzyme with Acetylcholinesterase

We report the existence, in Torpedo marmorata tissues, of a cholinesterase species (sensitive to 10(-5) M eserine) that differs from acetylcholinesterase (AChE, EC 3.1.1.7) in several respects: (a) The enzyme hydrolyzes butyrylthiocholine (BuSCh) at about 30% of the rate at which it hydrolyzes acetylthiocholine (AcSCh), whereas Torpedo AChE does not show any activity on BuSCh. (b) It is not inhibited by 10(-5) M BW 284C51, but rapidly inactivated by 10(-8) M diisopropylfluorophosphonate. (c) It does not exhibit inhibition by excess substrate up to 5 X 10(-3) M AcSCh. (d) It does not cross-react with anti-AChE antibodies raised against purified Torpedo AChE. This enzyme is obviously homologous to the "nonspecific" or pseudocholinesterase (pseudo-ChE, EC 3.1.1.8) that exists in other species, although it is closer to "true" AChE than classic pseudo-ChE in several respects. Thus, it shows the highest Vmax with acetyl-, and not propionyl- or butyrylthiocholine, and it is not specifically sensitive to ethopropazine. Pseudo-ChE is apparently absent from the electric organs, but represents the only cholinesterase species in the heart ventricle. Pseudo-ChE and AChE coexist in the spinal cord and in blood plasma, where they contribute to AcSCh hydrolysis in comparable proportions. Pseudo-ChE exists in several molecular forms, including collagen-tailed forms, which can be considered as homologous to those of AChE. In the heart the major component of pseudo-ChE appears to be a soluble monomeric form (G1). This form is inactivated by Triton X-100 within days.(ABSTRACT TRUNCATED AT 250 WORDS)     

The proteins of the ejaculatory bulbs in different species of Drosophila

A comparative electrophoretic study or ejaculatory bulb proteins in 29 different Drosophila species has been carried out. In all analyzed species, ejaculatory bulb contains a major component (designated as PEB). It has molecular mass of 61-65 kDa in the species of virilis group, 33-36 kDa in species of obscura group, and 34-56 kDa in species of melanogaster group. Using immunoblotting technique, we have demonstrated that PEB is introduced into organs of female sex tract during mating. The nature and significance of revealed interspecific differences in PEB proteins has been discussed.