C3 Homologue Research Articles

Study of deviation from normal liquid crystal behavior of mesomorphic-isotropic transition curve in a chalconyl ester series with equipolar terminal end groups

ABSTRACTA novel chalconyl ester homologous series RO.C6H4.COO.C6H4.CO-CH:CH-C6H4.OC8H17(p) synthesized and studied with a view to understanding and establishing the relation between molecular structure and Liquid Crystal (LC) properties of thermotropic mesomorphs. The novel series consists of eleven homologous (C1 to C16). Enantiotropicnematic type of mesophase formation commences from C3 homologue and continued up to the last C16 homologue of a novel series. Smectogenic character is totally absent for the novel series. Transition temperatures and the textures of nematic phase were determined through an optical polarizing microscopy (POM) equipped with a heating stage. Textures of nematic phase are threaded or Schlieren. Transition curve Cr-N/I and N-I behaved in normal manner except C8 homologue which showed negligible deviation from normal behavior. N-I transition curve exhibited odd–even effect. Analytical and structural data supported the molecular structures of homologues. Average thermal stability for nematic is 98.88°C whose degree of mesomorphismvary from 12.0°C to 37.0°C. Evaluated thermometric data of present novel series are compared with structurally similar series. Group efficiency order for nematic on the basis of thermal stability, early commencement of mesophase and the degree of mesomorphism. Thus, present series is predominantly nematogenic and lower middle ordered melting type the low degree of mesomorphism.

Mesomorphism dependence on molecular rigidity and substitution of same functional group on lateral or terminal position of tailed phenyl ring

ABSTRACTNovel liquid crystal materials (LCs) of low temperature range (53°C to 75°C) have been synthesized through a series of chalconyl derivatives consisting of two phenyl rings bonded through a –CH˭CH‒CO‒ central bridge to study the effect of molecular structure on LC properties in general and with a focus on molecular rigidity. The novel homologues series (C1 to C18) consists of thirteen homologues with general formula RO‒C6H4‒CH˭CH‒CO‒C6H4‒OC10H21(n) (meta). The C1, C2, C3 homologues are nonliquid crystals (NLC) and the rest of the homologues (C4 to C18) are either monotropic or enantiotropic liquid crystals. C4 to C6 homologues are enantiotropicnematic and the rest of the mesomorphic homologues are (C7 to C18) monotropicsmectic in addition to monotropicnematic character. Transition and melting temperatures including textures of homologues were determined by an optical polarizing (POM) microscopy equipped with a heating stage. Textures of a nematic phase are threaded or Schlieren, and that of the smectic phase are of the type Smectic A or C as judged directly from the heating top of the microscope. Thermal stability for smectic is very poor and of the nematic is (N-I) 69.3°C whose, total mesophase length ranges between 07.0 to 14.0°C at C8 and C4 homologues respectively.

Mesomorphism in chloro substituted isomeric series including chalconyl central bridge

ABSTRACTA novel homologous series of thermotropic liquid crystals α-4-(4′-n-alkoxy benzoyloxy phenyl) β-2″-chloro benzoyl ethylenes have been synthesized and studied with a view to understand and establish the effect of molecular structure on liquid crystal (LC) properties with reference to molecular flexibility in isomeric series with differing positional status of same functional group. Novel homologues series consist of 12 homologues C1 to C16. C1, C2, and C3 homologues are nonliquid crystals (NLC) and rest of the homologues are liquid crystals. C10 to C16 homologues are enantiotropically smectogenic plus nematogenic and C4 to C8 homologues are enantiotropic nematic. The texture of nematogenic derivatives is threaded or schlieren and that of the smectic mesophase are focal conic of the type smectic A or C. Analytical, thermal and spectral data supported molecular structures of novel homologues. Transition temperatures as determine by a hot stage polarizing optical microscopy (POM) were plotted against number of carbon atom present in n-alkyl chain ‘R’ of left n-alkoxy (-OR) group and the phase transition curves Cr–I/M, Sm–N, N–I were obtained on linking like or related points. The odd–even effect is observed for the N–I transition curve and thus transition curves behaved in normal manner. The even-membered nematic transition curve occupied higher position than the odd-membered transition curve. Present series is predominantly nematogenic and partly smectogenic with middle-ordered melting type.

Mesomorphism and molecular flexibility in novel chalconyl derivatives with two phenyl rings

ABSTRACTA novel chalconyl liquid crystalline (LC) homologous series with two phenyl rings and one central bridge RO−C6H4−CH=CH–CO−C6H4(O−C18H37) (meta) has been synthesized and studied with a view to understanding and establishing the effects of molecular structure on thermotropic LC behaviors or properties. Homologous series of present investigation (C1–C18) consists of thirteen homologues, and thermotropic mesomorphism for nematic and smectic commences from C3 and C6 homologues respectively. The C3, C4, and C5 homologues are enantiotropically nematic, whereas, the homologues from C6 to C18 are monotropically smectic plus nematic. Melting points and transition temperatures were determined using a polarizing optical microscope (POM) equipped with a heating stage. The textures of the nematic phase are threaded or Schlieren and that of a smectic phase are fan shaped of smectic-A or smectic-C type. The Cr−I/M, N−I/I−N, and N-Sm transition curves behave in the normal manner, and the Cr-I/M exhibits an odd-even effect. Analytical, thermal, and spectral data confirm the molecular structures. Thermal stabilities of smectic and nematic are low. Mesophase lengths are very short, ranging between 1–8°C and 14°C. The novel compounds are compared with a known series.

Synthesis and study of mesomorphic properties of azoester compounds

ABSTRACTIn order to investigate the influence of the terminal substitution on mesomorphism, the newly synthesized homologues series based on azoester have been synthesized. The influence of the structure of the mesogenic core has been present in this study, effect of hydrocarbon chain length and flexibility at terminal side effect on mesomorphism was represents in this case. In this investigation, we represent a series consisting of thirteen (C1–C18) homologue. In which, C1 to C3 homologue are nonmesomorphic. While C4–C18 shows smectic as well as nematic mesophase enantiotropically. Analytical and spectral data confirmed the molecular structures of homologues. All these compounds were characterized by elemental analysis and Fourier transform infrared [FTIR] and 1H NMR. Their mesomorphic properties were measured by optical polarized light microscopy and differential scanning calorimetry (DSC) and PXRD.

Characterization of the gene encoding component C3 of the complement system from the spider Loxosceles laeta venom glands: Phylogenetic implications

A transcriptome analysis of the venom glands of the spider Loxosceles laeta, performed by our group, in a previous study (Fernandes-Pedrosa et al., 2008), revealed a transcript with a sequence similar to the human complement component C3. Here we present the analysis of this transcript. cDNA fragments encoding the C3 homologue (Lox-C3) were amplified from total RNA isolated from the venom glands of L. laeta by RACE-PCR. Lox-C3 is a 5178 bps cDNA sequence encoding a 190kDa protein, with a domain configuration similar to human C3. Multiple alignments of C3-like proteins revealed two processing sites, suggesting that Lox-C3 is composed of three chains. Furthermore, the amino acids consensus sequences for the thioester was found, in addition to putative sequences responsible for FB binding. The phylogenetic analysis showed that Lox-C3 belongs to the same group as two C3 isoforms from the spider Hasarius adansoni (Family Salcitidae), showing 53% homology with these. This is the first characterization of a Loxosceles cDNA sequence encoding a human C3 homologue, and this finding, together with our previous finding of the expression of a FB-like molecule, suggests that this spider species also has a complement system. This work will help to improve our understanding of the innate immune system in these spiders and the ancestral structure of C3.

Mesomorphism dependence on central bridges and the efficiency order of the tail group

ABSTRACTA novel homologous series: RO-C6H4‒CH˭CH‒COO‒C6H4‒CH˭N-C6H3 (CH3)2 of ortho-meta Schiff's bases has been synthesized and studied with a view to understanding and establishing the effects of molecular structure on mesomorphic properties and to provide a source of novel liquid crystalline (LC) materials. The series consists of 13 homologues (C1 to C8, C10, C12, C14, C16 & C18). C1 and C3 homologues are nonmesomorphic, C2 and C4monotropicnematic, C6 and C7monotropicsmectic in addition to enantiotropicnematic, C5 is only enantiotropicnematic, C8, C10, C12 are enantiotropically smectogenic plus nematogenic and C14, C16, C18 homologues are enantiotropically smectic only. Textures and transition temperatures were determined using an optical polarizing microscope equipped with a heating stage. Analytical and spectral data confirm the molecular structures. Average smectic and nematic thermal stabilities are 100.16°C and 110.83°C, respectively. Mesomorphic properties of present novel series are compared with structurally similar homologous series.

Dependence of liquid crystallinity on molecular rigidity

A novel homologous series of liquid crystals (LC) of chalconyl derivatives is synthesized and studied with a view to understanding and establishing the effects of molecular structure on liquid crystal properties. The novel series consists of 12 homologues. Nematogenic LC property commences from C3 and continues up to C14 and the smectogenic mesophase is exhibited from C4 to C16. The C3 homologue is a monotropic nematic and the rest of the homologues are enantiotropically smectic and nematic or only smectic (C16). Transition curves Cr-Sm, Sm-N, Cr-I, and N-I behave in normal manner with exhibition of odd-even effect, showing phase behaviors of the series.

Molecular Rigidity/Flexibility Dependence of Mesomorphism

A novel chalconyl homologous series of liquid crystalline derivatives; RO - C6H4- CH : CH - COO - C6H4-CO - CH : CH - C6H4 - OC8H17 (n) (para) have been synthesized and studied with a view to correlate the thermotropic liquid crystal (LC) behavioural properties and the molecular structure of a substance. Present novel series consisted of eleven homologue members (C1 to C16) whose, only nematogenic mesomorphism commences from C3 homologue and continued upto C16 homologue in enantiotropic manner with absence of smectogenic character. Transition temperatures and textures of nematic phase were determined using an optical polarizing microscopy equipped with a heating stage (POM). Transition curve Cr-N/I behaved in normal manner. N-I transition curve exhibited odd-even effect and deviated from its normal descending tendency from and beyond C8 homologue and adopted serpantile shape from C8 to C16 homologue in deviating manner. Textures of the nematic phase are threaded or schlieren. Analytical and spectral data supported molecular structures of homologues. Thermal stability for nematic is 112.66 and the degree of mesomorphism vary from 5.00C to 44.00C at the C12 andC4 homologue respectively. It is a middle ordered melting type series, whose relative group efficiency order for nematic derived.

Molecular Flexibility of Longer n-Alkoxy Tail Group Operated Mesomorphism

A novel homologous series RO-C6H4-CH=CH-COO-C6H4-CO-CH=CH-C6H4-OC16H33 (n) para of chalconyl ester derivatives have been synthesized and studied with a view to understand and establish the effect of molecular structure on thermotropic liquid crystalline state of the substances and to provide novel liquid crystal (LC) materials to the researchers working in an unique multidisciplinary LC state of the substances. A novel chalconyl ester series consists of thirteen ( C1 to C18) homologues. C5 to C18 homologues are enantiotropically nematogenic without exhibition of smectogenic property, while the rest of the C1 to C4 homologues are nonliquid crystals (NLC). Transition temperatures and textures were determined by polarizing optical microscopy (POM) equipped with a heating stage. Textures of a nematic phase are threaded or schlieren. Cr-I/N and N-I transition curves of a phase diagram behaved in normal manner except negligible abnormality at C14 homologue. Odd-even effect is exhibited by N-I transition curve. Analytical and Spectral data supported molecular structures of the homologues. Thermal stability for nematic is 97.33°C and the degree of mesomorphism vary maximum 24.0°C at C5 homologue to minimum 11.0°C at C10 homologue respectively. Latent transition temperatures (LTT) are determined for nonmesomorphic homologues C4 (90°C) and C3 (114°C) homologues by extrapolation method of transition curve. LC properties of a novel series are (thermometric) compared with structurally similar series.

Molecular Rigidity/Flexibility Dependence of Mesomorphism

A novel chalconyl homologous series of liquid crystalline derivatives; RO - C6H4- CH : CH - COO - C6H4-CO - CH : CH - C6H4 - OC8H17 (n) (para) have been synthesized and studied with a view to correlate the thermotropic liquid crystal (LC) behavioural properties and the molecular structure of a substance. Present novel series consisted of eleven homologue members (C1 to C16) whose, only nematogenic mesomorphism commences from C3 homologue and continued upto C16 homologue in enantiotropic manner with absence of smectogenic character. Transition temperatures and textures of nematic phase were determined using an optical polarizing microscopy equipped with a heating stage (POM). Transition curve Cr-N/I behaved in normal manner. N-I transition curve exhibited odd-even effect and deviated from its normal descending tendency from and beyond C8 homologue and adopted serpantile shape from C8 to C16 homologue in deviating manner. Textures of the nematic phase are threaded or schlieren. Analytical and spectral data supported molecular structures of homologues. Thermal stability for nematic is 112.66 and the degree of mesomorphism vary from 5.00C to 44.00C at the C12 andC4 homologue respectively. It is a middle ordered melting type series, whose relative group efficiency order for nematic derived.

Molecular Flexibility of Longer n-Alkoxy Tail Group Operated Mesomorphism

A novel homologous series RO-C6H4-CH=CH-COO-C6H4-CO-CH=CH-C6H4-OC16H33 (n) para of chalconyl ester derivatives have been synthesized and studied with a view to understand and establish the effect of molecular structure on thermotropic liquid crystalline state of the substances and to provide novel liquid crystal (LC) materials to the researchers working in an unique multidisciplinary LC state of the substances. A novel chalconyl ester series consists of thirteen ( C1 to C18) homologues. C5 to C18 homologues are enantiotropically nematogenic without exhibition of smectogenic property, while the rest of the C1 to C4 homologues are nonliquid crystals (NLC). Transition temperatures and textures were determined by polarizing optical microscopy (POM) equipped with a heating stage. Textures of a nematic phase are threaded or schlieren. Cr-I/N and N-I transition curves of a phase diagram behaved in normal manner except negligible abnormality at C14 homologue. Odd-even effect is exhibited by N-I transition curve. Analytical and Spectral data supported molecular structures of the homologues. Thermal stability for nematic is 97.33°C and the degree of mesomorphism vary maximum 24.0°C at C5 homologue to minimum 11.0°C at C10 homologue respectively. Latent transition temperatures (LTT) are determined for nonmesomorphic homologues C4 (90°C) and C3 (114°C) homologues by extrapolation method of transition curve. LC properties of a novel series are (thermometric) compared with structurally similar series.

On the Functional Overlap between Complement and Anti-Microbial Peptides.

Intriguingly, activated complement and anti-microbial peptides share certain functionalities; lytic, phagocytic, and chemo-attractant activities and each may, in addition, exert cell instructive roles. Each has been shown to have distinct LPS detoxifying activity and may play a role in the development of endotoxin tolerance. In search of the origin of complement, a functional homolog of complement C3 involved in opsonization has been identified in horseshoe crabs. Horseshoe crabs possess anti-microbial peptides able to bind to acyl chains or phosphate groups/saccharides of endotoxin, LPS. Complement activity as a whole is detectable in marine invertebrates. These are also a source of anti-microbial peptides with potential pharmaceutical applicability. Investigating the locality for the production of complement pathway proteins and their role in modulating cellular immune responses are emerging fields. The significance of local synthesis of complement components is becoming clearer from in vivo studies of parenchymatous disease involving specifically generated, complement-deficient mouse lines. Complement C3 is a central component of complement activation. Its provision by cells of the myeloid lineage varies. Their effector functions in turn are increased in the presence of anti-microbial peptides. This may point to a potentiating range of activities, which should serve the maintenance of health but may also cause disease. Because of the therapeutic implications, this review will consider closely studies dealing with complement activation and anti-microbial peptide activity in acute inflammation (e.g., dialysis-related peritonitis, appendicitis, and ischemia).

Insights into complement convertase formation based on the structure of the factor B-cobra venom factor complex

Immune protection by the complement system critically depends on assembly of C3 convertases on the surface of pathogens and altered host cells. These short-lived protease complexes are formed through pro-convertases, which for the alternative pathway consist of the complement component C3b and the pro-enzyme factor B (FB). Here, we present the crystal structure at 2.2-A resolution, small-angle X-ray scattering and electron microscopy (EM) data of the pro-convertase formed by human FB and cobra venom factor (CVF), a potent homologue of C3b that generates more stable convertases. FB is loaded onto CVF through its pro-peptide Ba segment by specific contacts, which explain the specificity for the homologous C3b over the native C3 and inactive products iC3b and C3c. The protease segment Bb binds the carboxy terminus of CVF through the metal-ion dependent adhesion site of the Von Willebrand factor A-type domain. A possible dynamic equilibrium between a 'loading' and 'activation' state of the pro-convertase may explain the observed difference between the crystal structure of CVFB and the EM structure of C3bB. These insights into formation of convertases provide a basis for further development of complement therapeutics.

Intracellular Delivery of Bioactive Peptides to RBL‐2H3 Cells Induces β‐Hexosaminidase Secretion and Phospholipase D Activation.

This investigation compared the secretory efficacies of a series of peptides delivered to the cytoplasm of RBL-2H3 mast cells. Mimetic peptides, designed to target intracellular proteins that regulate cell signalling and membrane fusion, were synthesised as transportan 10 (TP10) chimeras for efficient plasma membrane translocation. Exocytosis of beta-hexosaminidase, a secretory lysosomal marker, indicated that peptides presenting sequences derived from protein kinase C (PKC; C1 H-CRRLSVEIWDWDL-NH(2)) and the CB(1) cannabinoid receptor (C3 H-RSKDLRHAFRSMFPSCE-NH(2)) induced beta-hexosaminidase secretion. Other peptide cargoes, including a Rab3A-derived sequence and a homologue of C3, were inactive in similar assays. Translocated C1 also activated phospholipase D (PLD), an enzyme intimately involved in the regulated secretory response of RBL-2H3 cells, but C1-induced secretion was not dependent upon phosphatidate synthesis. Neither down-regulation of Ca(2+)-sensitive isoforms of PKC nor the application of a selective PKC inhibitor attenuated the secretory efficacy of C1. These observations indicate that the molecular target of C1 is a protein involved in the regulated secretory pathway that is upstream of PLD but is not a PKC isoform. This study also confirmed that TP10 is a relatively inert cell-penetrating vector and is, therefore, widely suitable for studies in cells that are sensitive to peptidyl secretagogues.

The gene encoding the sea urchin complement protein, SpC3, is expressed in embryos and can be upregulated by bacteria

Sea urchins have an innate immune response that functions in the absence of adaptive capabilities. It is mediated, in part, by components of the complement system, an important subsystem of the innate response in mammals. A homologue of complement C3, SpC3, has been identified in adult Strongylocentrotus purpuratus and is expressed in coelomocytes. In this study, transcript levels from the gene, Sp064, which encodes SpC3, were examined in developing embryos and found to be present in unfertilized eggs and throughout embryogenesis with a peak in transcript levels just prior to and during gastrulation. In addition, continuous exposure of embryos, beginning with the hatched blastula stage, to heat killed Vibrio diazatrophicus, a marine pathogen of sea urchins, significantly increased Sp064 message content in plutei compared to unexposed controls. These results suggest that sea urchin embryos may use a complement-based immune system for defense against pathogens in their aquatic environment.

The acid-catalysed polycondensation of 2-acetoxymethylthiophenes. Kinetics and mechanisms

This article describes the kinetics and mechanism of the acid-catalysed polycondensation of 2-acetoxymethylthiophene and its C3 and C5 methylated homologues. Numerous experiments were carried out by varying different parameters, such as temperature, solvent and acidic catalyst concentration. The presence of a methyl substituent at C3 or C5 position did not affect the qualitative features of the polymerisations, whereas their rates were enhanced owing to the donor character of the appended substituent. All reactions followed a first order behaviour with respect to the monomer and the activation energies were all around 50kJmol−1. The DP of these products grew as a function of reaction time to reach values of about 40 at complete monomer consumption and thereafter chain growth could be reactivated by further monomer additions. Initiation in the presence of added polymer led to its grafting with a substantial increase in molecular weight. The evidence gathered suggests these polycondensations bear a living character.

A complement component C3a-like peptide stimulates chemotaxis by hemocytes from an invertebrate chordate—the tunicate, Pyura stolonifera

Recent evidence suggests that the complement system evolved as a critical host defence mechanism among invertebrates, long before the origin among vertebrates of adaptive immune responses mediated by somatically re-arranging antibodies. The current study supports that contention by identifying a complement component C3a-like peptide in the tunicate, Pyura stolonifera. Activation of P. stolonifera serum with common inflammatory elicitors (lipopolysaccharide and zymosan) resulted in the proteolytic generation of an 8.5 kDa peptide, and concomitantly conferred chemoattractant activity on the serum. The 8.5 kDa peptide shares substantial amino acid sequence homology with a previously characterised tunicate complement component C3-like protein (72% amino acid identity in an 18 amino acid overlap). It is also recognised by an anti-C3 antiserum that is known to cross react with tunicate C3 homologues. Hemocyte migration assays performed with the 8.5 kDa peptide that had been partially purified by gel filtration confirmed that the molecule acts as a powerful chemotactic agent. This suggests that the proteolytic activation of tunicate C3-like molecules can initiate inflammatory responses involving cellular recruitment by liberating a pro-inflammatory peptide akin to the vertebrate anaphylatoxin, C3a.

Thioester function is conserved in SpC3, the sea urchin homologue of the complement component C3

The amino acid sequence of the thioester site in the α chain of SpC3, the sea urchin homologue of C3, is conserved. This implies a conserved function of covalent bond formation with amine or hydroxyl groups on target molecules. When coelomic fluid (CF) was incubated with 14C-methylamine, a classic assay for thioester binding function, the α chain became labeled. When CF was treated to induce autolysis, peptide bond cleavage occurred at the thioester site. Autolysis could be blocked or reduced by pre-treating CF with either methylamine or yeast, both of which are known to bind to thioester sites C3 proteins from other organisms. The data suggest that SpC3 can bind to target cell surfaces, constituting indirect evidence that it can covalently bind to pathogen surfaces and function as an opsonin in vivo. This activity may be an important aspect of host defense in the sea urchin.

Collagenous lectins in tunicates and the proteolytic activation of complement.

Complement activation in vertebrates has traditionally been associated with the classical (antibody mediated) or alternative (spontaneously hydrolytic) pathways. Recently, a new mechanism of complement activation has been identified in which a collagenous lectin (collectin), mannose binding protein (MBP) and its associated serine protease (MASP) activate the central component of the complement system, C3 (Epstein, et al., 1996, Holmskov, et al., 1994, Hoppe and Reid, 1994, Lu, 1997). Two components of this lectin-mediated complement pathway have already been identified in invertebrates. Echinoderms express a C3 homologue and a number of other complement components, whilst a MASP-like serine protease and a C3 homologue have been identified in tunicates (Al-Sharif, et al., 1998, Azumi, et al., 1993, Nonaka, et al., 1998, Smith, et al., 1996, Smith, et al., 1998).KeywordsComplement ComponentCarbohydrate BindingOpsonic ActivityHigh Order OligomerAmino Acid Composition AnalysisThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.