Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “diverged evolution”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources
PubMed2001

[Classification of alcohol metabolizing enzymes and polymorphisms--specificity in Japanese].

Multiple forms and gene loci of human alcohol dehydrogenase (ADH EC: 1.2.1.3) and aldehyde dehydrogenase (ALDH, EC: 1.2.1.3) in the major pathway of alcohol metabolism have been found and characterized in the last two decades. With the coenzyme NAD, these enzymes catalyze the reversible conversion of organic alcohols to ketones or aldehydes, and aldehyde to acetic acid. The ADH genes are mapped to chromosome 4p21-25, but the ALDH genes are localized at different chromosomes. The cytochrome P450 2E1 (CYP2E1) gene, which is mapped to chromosome 10q24.3-qter contributes also the conversion of ethanol to acetaldehyde. Genetic polymorphisms have been reported in these alcohol metabolizing enzymes. The metabolisms of alcohol and acetaldehyde in liver and blood after drinking alcohol are thought to be influenced by the interactive action of these enzymes. Amongst the five major classes of the ADH subunits (alpha, beta, gamma, pi, chi, sigma), beta and gamma subunits show genetic polymorphisms. Recently a new nomenclature for ALDH genes has been recommend based on divergent evolution and chromosomal mapping. Two major isoforms designated as cytosolic ALDH1 and mitochondrial ALDH2 can be distinguished by their electrophoretic and kinetic properties as well as by their subcellular localization. Mitochondrial ALDH2 is a major enzyme in the oxidation of acetaldehyde derived from ethanol metabolism. The catalytic deficiency of ALDH2 isozyme is responsible for flushing and other vasomotor symptoms caused by higher acetaldehyde levels after alcohol intake. So far, frequencies of the two alleles of ALDH2 in Mongoloid have been reported in the different population groups. The catalytic deficiency of ALDH2 is caused by a structural point mutation at amino acid position 487, where a substitution of Glu to Lys resulting from a transition of G (C) to A (T) at 1510 nucleotide from the initiation codon has occurred. Individuals deficient in ALDH2 activity refrain from excessive drinking of alcohol due to the aversive reactions, leading to protection against alcoholism. Prevalence of the ALDH2*1 allele is associated with alcoholism, and subsequent studies have confirmed the allelic association with alcoholism in different ethnic groups. The effects of polymorphisms of ADH2 and CYP2E1 remained controversial, even in the same ethnic group. Investigation of mutations for the transacting cis-element in promoter region of the ALDH2 gene will provide important information with respect to regulation of this gene. Transfection assays using the first 600 bp of the upstream nucleotide sequences indicated that a region from -75 to -120 was necessary for the ALDH2 gene expression, and especially NF-Y/CP1 binding site from -92 to -96 (CCAAT box) is important in the expression of the gene. A novel polymorphism due to the nucleotide replacement at -357 G to A was found in all the population groups. Alcoholism is thought to be a multifactorial disease with complex mode of inheritance in addition to psychological and social factors, and many studies of family, adoption and twins concerning alcoholism have revealed that hereditary factor is an important determinant for developing alcoholism. Genetic association studies have contributed to the identification of a number of genetic risk factors for the chronic diseases influenced by genetic disorders and environmental factors.

Alcohol Dehydrogenase↗
PubMed1975

A comparison of the heme binding pocket in globins and cytochrome b5.

Of the 85 three-dimensionally characterized residues of cytochrome b5, 51 are found to be structurally and topologically equivalent to the globin fold. When these proteins have been superimposed, the heme irons are found to be less than 1.4 A separated and the heme normals are inclined by less than 9.5 degrees. The proximal histidine of the globins and two adjacent helices are equivalent to the sixth iron ligand and adjacent helices of cytochrome b5. Larger differences in structure are observed on the distal side of the heme, coincident with the most changeable part of the globin structures. The heme itself is rotated by 53 degrees about its normal but such a change is energetically minimal and conservative as the heme side groups are not directly involved in the function of the molecules. The beta-sheet of cytochrome b5 is inserted into a corresponding cavity of the globins forming an additional lining to the heme pocket. The roughly 50 residues missing at the carboxy end of the known cytochrome b5 fragment could correspond in part to the H helix in the globins. While it would seem probable that these similarities represent divergent evolution from a primordial heme-binding protein, the possibility of structural convergence to a functionally satisfactory protein cannot be excluded.

Amino Acid Sequence↗
PubMed1992

Cirrhotic changes in livers from children undergoing transplantation. Image analysis.

The pattern and extent of disorganization of the liver architecture were studied in 25 children undergoing orthotopic liver transplantation for cirrhosis. Image analysis techniques based on mathematical morphology were used to define seven parameters for each case, including fibrosis index (percentage of Sirius-red-stained areas), three categories of regenerative nodules (< 0.8, 0.8-1.6 and > 1.6 mm in diameter) and three categories of fibrous septa (< 0.4, 0.4-1.2 and > 1.2 mm in width). Fibrosis index ranged from 10.2% to 51.9%. Percentage of small nodules of infralobular size (< 0.8 mm in diameter) varied from 31.4% to 98.2%. Percentage of large nodules, > 1.6 mm in diameter, in only four cases was > 15%. Multivariate clustering analysis classified the cases into three main groups. One of them included only cases of cirrhosis secondary to parenchymal disease or to inborn errors of metabolism. In their pattern, tiny nodules predominated, and the percentage of slender septa, < 0.4 mm in diameter, was very high, although the overall fibrosis index was relatively low. Patients with biliary cirrhosis were classified into two groups. In one the fibrosis index was low and the size of the nodules variable, with 12% large nodules. In the other the fibrosis index was high, and small nodules, < 0.8 mm in diameter, predominated. No relationship was found with age at transplantation or previous portoenterostomy. A presumptive explanation for this divergent evolution might be the occurrence of cholangitic episodes. Overall fibrosis that the liver can sustain without failure is apparently limited.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Structure and organization of the human transglutaminase 1 gene.

Membrane-associated transglutaminases (TGase1) have recently been found to be common in mammalian cells, but it is not clear whether these derive from the same or different genes. In order to determine the complexity of this system, we have isolated and characterized the human gene (TGM1). The gene of 14,133 base pairs was found to contain 15 exons spliced by 14 introns. Interestingly, the positions of these introns have been conserved in comparison with the genes of two other transglutaminase-like activities described in the literature, but the TGM1 gene is by far the smallest characterized to date because its introns are relatively smaller. On the other hand, the TGase1 enzyme is the largest known transglutaminase (about 90 kDa), apparently because its gene acquired tracts that encode additional sequences on its amino and carboxyl termini that confer its unique properties. Southern blot analyses of total human genomic DNA cut with several restriction enzymes reveal only one band. Use of human-rodent cell hybrid panels and chromosomal in situ hybridization with biotin-labeled probes revealed that the human TGM1 gene maps to chromosome position 14q11.2-13. Such data suggest there is a single gene copy per haploid human genome. Comparisons of sequence identities and homologies indicate that the transglutaminase family of genes arose by duplications and subsequent divergent evolution from a common ancestor but later became scattered in the human genome. Although our present Southern blot and chromosomal localization studies revealed no restriction fragment length polymorphisms, comparisons of published sequences and our genomic clone indicate there are two sequence variants for TGase1 within the human population. The rare smaller variant contains a two-nucleotide deletion near the 5'-end, uses an alternate initiation codon, and differs from the common larger variant only in the first 15 amino acids. Furthermore, the DNA sequences of intron 14 possess several tracts of dinucleotide repeats that by polymerase chain reaction analysis show wide size polymorphism within the human population. Accordingly, this gene system constitutes a useful polymorphic marker for genetic linkage analyses.

Amino Acid Sequence↗
PubMed1992

The complete cDNA sequence of bovine coagulation factor V.

Lack of availability of a primary structure for bovine factor V has hindered detailed analysis of a vast majority of structure-function correlations on this molecule. To determine the primary structure of bovine factor V, we used liver mRNA as a template for the synthesis of three cDNA libraries. The sequences of seven overlapping cDNA clones infer two bovine factor V variants. Variant 1 results in a 6910-basepair (bp) cDNA including 103 bp of 5'-untranslated sequence, 6633 bp of coding sequence and 171 bp of 3'-untranslated sequence with a putative polyadenylation site. Variant 2 differs only in the size of the coding sequence (6618 bp). The open reading frame translates to factor V consisting of 2211 (or 2206) amino acids including a 28-amino acid signal peptide. Comparison of the amino acid sequences with human factor Va reveals 84% identity for the heavy and 86% for the light chains. In contrast, the B domain (connecting region) exhibits only 59% identity relative to the human molecule. The bovine B domain contains two repeats of a 14-amino acid structure that is contained only once in the human sequence. Bovine factor V lacks one of the nine amino acid repeats and one of the 17 amino acid repeats present in the human B domain. Factor V has little homology to the factor VIII molecule in the B domain. The 17-amino acid repeat missing in bovine factor V allows identification of an 18-amino acid sequence that is homologous to the B domain of human factor VIII. These 18 amino acids may either constitute the unique vestige of a divergent evolution between the B domains of factors V and VIII or reveal the convergent evolution toward a critical epitope involved in the activation of both procofactors.

Amino Acid Sequence↗
PubMed1991

Deacetoxycephalosporin C hydroxylase of Streptomyces clavuligerus. Purification, characterization, bifunctionality, and evolutionary implication.

Deacetoxycephalosporin C hydroxylase from cell-free extracts of Streptomyces clavuligerus was stabilized partially and purified to near homogeneity by three anion-exchange chromatographies, ammonium sulfate fractionation, and two gel filtrations. The hydroxylase was a monomer with a Mr of 35,000-38,000. alpha-Ketoglutarate, ferrous iron, and molecular oxygen were required for the enzyme activity. The hydroxylase was optimally active between pH 7.0 and 7.4 in a 3-(N-morpholino)propanesulfonic acid buffer and at 29 degrees C. It was stimulated by a reducing agent, particularly dithiothreitol or reduced glutathione, and ATP. The requirement for ferrous ion was specific, and at least one sulfhydryl group was apparently essential for the enzymatic hydroxylation. The Km values of the hydroxylase for deacetoxycephalosporin C and alpha-ketoglutarate were 59 and 10 microM, respectively, and the Ka for ferrous ion was 20 microM. In addition to its known hydroxylation of deacetoxycephalosporin C to deacetylcephalosporin C, the hydroxylase catalyzed effectively an analogous hydroxylation of 3-exomethylenecephalosporin C to deacetoxycephalosporin C. Surprisingly, the hydroxylase also mediated slightly a novel ring-expansion of penicillin N to deacetoxycephalosporin C. The substrate specificity of the hydroxylase is overlapping with but distinguishable from that of deacetoxycephalosporin C synthase, the enzyme which normally mediates the ring-expansion reaction (Dotzlaf, J. E., and Yeh, W. K. (1989) J. Biol. Chem. 264, 10219-10227). Furthermore, the hydroxylase exhibited an extensive sequence similarity to the synthase. Thus, the two enzymes catalyzing the consecutive reactions for cephamycin C biosynthesis in S. clavuligerus represent apparent products from a divergent evolution.

Amino Acid Sequence↗
PubMed1990

[Molecular cloning and structural-functional analysis of the arginine biosynthesis genes of the thermophilic bacterium Bacillus stearothermophilus].

Genes encoding arginine biosynthesis of Bacillus stearothermophilus strain 718 were cloned in the mutant argA strain of the Escherichia coli K-12. The arg genes were shown to be located on the 3.7 kb DNA fragment in the following order: argA--argE--argB. The expression of the argA gene of B. stearothermophilus on the multicopy vehicle is twofold higher in argR- strain of E. coli K-12 than is isogenic argR+ strain. According to hybridization analysis argA genes of B. stearothermophilus and B. subtilis have low level of homology, which is the evidence of their evolutional divergence.

Arginine↗
PubMed1989

Human pepsinogen C (progastricsin). Isolation of cDNA clones, localization to chromosome 6, and sequence homology with pepsinogen A.

The entire pepsinogen C (PGC) coding sequence was determined by analysis of a series of five overlapping cDNA clones identified in a library constructed from human gastric mucosa poly(A+) RNA. A partial cDNA clone was initially identified using a 256-fold degenerate oligonucleotide probe for amino acid residues 4-12 of pepsin C, and subsequently 4 additional clones were identified upon rescreening with a probe complementary to the 5' region of the original cDNA clone. Northern analysis of gastric mucosa poly(A+) RNA with a PGC cDNA probe revealed an mRNA 1.5-kilobase species that was indistinguishable from that detected with a human pepsinogen A (PGA) cDNA probe. In contrast, the PGC and PGA cDNA probes detected distinct genomic restriction fragments indicating there was no detectable cross-hybridization under high stringency conditions. The PGC gene was localized to human chromosome 6 by analysis of a panel of human x mouse somatic cell hybrids. The regions containing the active site aspartyl groups of PGC are conserved in relationship to several other aspartic proteinases. We propose that the absence of detectable immunologic cross-reactivity between the two groups of human pepsinogens, A and C, results from divergent evolution of sequences located on the surface of the zymogens in contrast to the strongly conserved active site regions located within the binding cleft of the enzymes that are inaccessible for antigenic recognition.

Amino Acid Sequence↗
PubMed1989

Multiplicity of heme oxygenase isozymes. HO-1 and HO-2 are different molecular species in rat and rabbit.

We report on the detection and characterization of two forms of heme oxygenase in rabbit tissues and provide data suggesting that heme oxygenases in rat and rabbit are not identical and constitute a group of heterogenous proteins. Certain molecular properties, however, are shared by the isozymes in rat and rabbit; the predominant form of the enzyme in control liver and testis is HO-2, in the liver HO-1 is the inducible form, and in the brain HO-1 is not detectable. HO-1 was purified from liver of rabbits treated with bromobenzene to near homogeneity with a specific activity of 8,270 nmol of bilirubin/mg/h and compared with a homogenous preparation of rat HO-1 with a specific activity of 6,220, also obtained from bromobenzene-treated animals. Rat and rabbit HO-1, on sodium dodecyl sulfate-polyacrylamide gel, had molecular weights of 30,000 and 30,700, respectively. Rabbit HO-2 was partially purified from testis to a specific activity of 386 nmol of bilirubin/mg/h and compared with a purified preparation of rat testis HO-2 with a specific activity of 5,700. Using Western immunoblotting, rabbit HO-2 displayed intense cross-reactivity with antibody raised in rabbit to sodium dodecyl sulfate-denatured rat HO-2, and had a substantially larger molecular weight than the rat HO-2 (42,000 versus 36,000). Rabbit HO-1 did not cross-react with antibody to rat HO-1 which was also raised in rabbit. Unlike the rat enzymes, rabbit HO-1 and HO-2 did not differ in thermolability. It is speculated that HO-1 in rat and rabbit, and possibly HO-2, have evolved from divergent evolution of a common ancestral gene(s).

Animals↗
PubMed1985

Primary structure of bovine matrix Gla protein, a new vitamin K-dependent bone protein.

The complete amino acid sequence of bovine bone matrix Gla protein (MGP) was determined by automatic sequence analysis of the intact protein and of peptides isolated from tryptic and BNPS-skatole digests. This 79-residue, vitamin K-dependent protein contains a single disulfide bond and 4.8 gamma-carboxyglutamate (Gla) residues, one each at positions 37, 41, 48, and 52, and 0.8 Gla and 0.2 Glu at position 2. There is sufficient sequence homology between MGP and bone Gla protein (BGP) to indicate that these two bovine bone proteins arose by gene duplication and subsequent divergent evolution. Although MGP has a very low solubility in water compared to BGP, there is no hydrophobic domain in MGP which could account for its insolubility, and the overall fraction of hydrophobic residues is 32% for MGP compared to 43% for BGP. MGP is the first vitamin K-dependent protein to be discovered which has several non-gamma-carboxylated residues to the NH2-terminal side of its Gla residues. The presence of NH2-terminal Glu residues between the putative targeting domain for the gamma-carboxylase in the MGP leader sequence and the mid-molecule Gla residues suggests that the gamma-carboxylase may have additional, as yet unrecognized, specificity requirements which determine the susceptibility of Glu residues for gamma-carboxylation.

1-Carboxyglutamic Acid↗
PubMedDate not supplied

[Homology of lysozymes of bacterial and vertebrate origin].

Theoretical analysis of structural and functional organization of vertebrate lysozymes, T4-phage lysozyme, lambda-phage endolysin and extracellular lysozyme of Chalaropsis species suggests a genetic relationship between the enzymes in question. It has been shown that the lysozyme sequences exhibit both inter- and intramolecular homology. The obtained data lend support to the concept postulating a common ancestor for the lysozyme family and subsequent divergent evolution of these proteins. The two-component primary structure of lysozymes can result from structural gene duplication and allows to explain similar catalytic activity and different substrate specificity of these enzymes by the differentiation and specialization of functions of the N- and C-components of the protein chains.

Amino Acid Sequence↗
PubMed1994

Cardiac development in the dogfish (Scyliorhinus canicula): a model for the study of vertebrate cardiogenesis.

We have studied the cardiac development of the dogfish (Scyliorhinus canicula) in six serially sectioned embryos ranging from 14 to 40 mm in total length. Our preliminary results show some significant similarities with the cardiac development of higher vertebrates, in spite of about 400 millions years of divergent evolution. The dogfish cardiac tube is composed of endocardium and myocardium separated by a thick layer of cardiac jelly. Large clefts form in the atrial and ventricular myocardium before the cardiac jelly disappears. These clefts seem to be related to the origin of the intertrabecular sinusoids. Myocardial pores in the sinus venosus and atrium might allow the flow of some cardiac jelly to the subepicardial space. Two atrioventricular and three conal endocardial cushions are formed by epithelial-mesenchymal transformation. The atrioventricular and conal valves seem to develop from these cushions, while the sinoatrial valve seems to derive from two transversal infoldings of the cardiac wall. The epicardium forms from mesothelial cells proceeding first from the liver and sinus venosus lining, and then from the developing septum transversum. A subepicardial space appears early and it is populated by mesenchymal cells which seem to proceed at least partly from the epicardium. These subepicardial cells apparently form capillary-like structures some of which coalesce in large annular veins around the atrioventricular and conoventricular grooves. The veins connect with ventricular sinusoids and the sinus venosus lumen.

Animals↗
PubMed1994

Allosteric control of the substrate specificity of the anaerobic ribonucleotide reductase from Escherichia coli.

The reduction of ribonucleotides is catalyzed by different enzymes in aerobic and anaerobic Escherichia coli, each with a different primary and quaternary structure. Here, we describe the allosteric regulation of the substrate specificity of the anaerobic ribonucleoside triphosphate reductase. The enzyme reduced ribonucleotides at a low basal rate. Reduction was stimulated up to 10-fold by an appropriate modulator (dGTP for ATP reduction, ATP for CTP and UTP reduction, and dTTP for GTP reduction). dGTP and dTTP inhibited the reduction of the "incorrect" substrate; dATP inhibited reduction of all four. From kinetic, effector binding, and competition experiments we conclude that the enzyme has two classes of sites, one that binds ATP and dATP and regulates pyrimidine ribonucleotide reduction ("pyrimidine site"), the other that binds dATP, dGTP, and dTTP and regulates purine ribonucleotide reduction ("purine site"). This model differs slightly from the model for the aerobic reductase, but the physiological consequences remain the same and explain how a single enzyme can provide a balanced supply of the four dNTPs. The similarity of a highly sophisticated control mechanism for the aerobic and anaerobic enzymes suggests that both arose by divergent evolution from a common ancestor, in spite of their different structures.

Adenosine Triphosphate↗
PubMed1993

A second form (beta isoform) of nucleoside diphosphate kinase from rat. Isolation and characterization of complementary and genomic DNA and expression.

Complementary and genomic clones for a second form (the beta isoform) of rat nucleoside diphosphate kinase were isolated. Structural studies revealed that nucleotide and deduced amino acid sequences of the beta isoform were quite similar to those of the alpha isoform (identities were 82 and 89%, respectively), which were delineated in our previous study (Kimura, N., Shimada, N., Nomura, K., and Watanabe, K. (1990) J. Biol. Chem. 265, 15744-15749). The gene encoding the beta isoform, covering 10 kilobases and comprising five exons, was located in tandem in the immediate vicinity (at a 3-kilobase distance) of the 5' upstream of the alpha isoform gene which was recently reported from this laboratory (Ishikawa, N., Shimada, N., Munakata, Y., Watanabe, K., and Kimura, N. (1992) J. Biol. Chem. 267, 14366-14372), suggesting their generation by gene duplication. The exon-intron junctions were exactly conserved between the two genes. Southern blot analyses showed that unidentified fragments cross-reacted with the beta isoform cDNA probe besides those containing the genuine gene, and at least two of them were identified as possible processed pseudogenes. Northern and dot blot hybridization studies demonstrated that the alpha isoform was more expressed than the beta isoform in rat tissues examined except brain, from which the isoform designation was derived. These results suggest independent expression and specific roles of these isoforms in the cell. Comparative studies between rat and human isoforms indicate that the isoforms could have differentiated before the two species evolutionally diverged.

Amino Acid Sequence↗
PubMedDate not supplied

[Considerations on the origin of the diversity of immunoglobulins (author's transl)].

In spite of the numerous theories proposed to explain the origin of the diversity of immunoglobulins, none can define satisfactorily the nature of the generator of diversity and its mode of action. Even the concept of the variable and constant portions of immunoglobulin chains is no longer valid which opens up the question about the hypothetical existence of the V and C genes. Moreover, phylogenetic considerations strongly suggest that there is a fundamental difference in the mechanism of amino acid substitution for the immunoglobulins and for homologous proteins undergoing normal divergent evolution. A conceptionally and functionally simple mechanism, based on a variable translation of the immunoglobulin mRNA, has been suggested as the generator of diversity (Rev. canad. Biol., 1969, 28, 179). The criteria of this mechanism are (1) the presence of inosine in the mRNA and (2) the existence of a series of overmethylated tRNAs for the selective recognition of inosine-containing codons. Although the experimental proof for this mechanism is still lacking, it cannot be fortuitous that the lack of adenosine deaminase is associated with immune deficiency and that an increased tRNA methylase activity exists in plasmocytomas.

Biological Evolution↗
PubMed1993

Differential usage of the carboxyl-terminal region among aldolase isozymes.

Sequence homology among nonconserved residues 357-362 of the COOH-terminal region in fructose-1,6-bisphosphate aldolases correlates with isozyme classification of aldolases. Recombinant chimers of human liver and maize aldolases were constructed by exchanging residues 357-362 with those from muscle, maize, and liver isozyme and by insertion in the maize sequence at position 349 rabbit muscle and liver residues 346-349. Activity variation among the chimers relative to native controls ranged from less than 10% to greater than 300% of Vm. Exchange of residues 357-362 significantly affected both Vm and Km without modifying catalytic efficiency kcat/Km, whereas insertion of residues 346-349 modified Vm and Km and increased catalytic efficiency. Steady state carbanion oxidation rates varied inversely with activity and were differentially affected with respect to equilibrium oxidation rates. Sequence exchange of residues 357-362 appears to modulate carbanion proton exchange, whereas sequence insertion of residues 346-349 modifies substrate and aldehyde interaction with C6 phosphate binding locus. Low intrinsic susceptibility to carboxypeptidase A degradation of the COOH terminus in liver aldolase is consistent with tight association of this COOH terminus in a conformation unfavorable for promoting high catalytic activity. Efficient carbanion protonation promoted by specific sequences 357-362 represents a mechanistic feature which distinguishes catalytically active maize and muscle isozymes from less active liver isozyme. Conservation of active site residues among aldolases suggests that isozyme diversity among aldolases arose from divergent evolution of the COOH-terminal sequence.

Amino Acid Sequence↗
PubMedDate not supplied

[Comparative characteristics of cestode parenchyma].

A comparative description is given of different connective tissue cells and the character of intercellular substance in the parenchyma of two species of cestodes of the order Pseudophyllidea and 4 species of the order Cyclophyllidea. The parenchyma of the cestodes has been shown to be a complex specialized tissue system evolving divergently. The first distinct morphological differences arise at the family level. The direction of the divergent evolution of the parenchyma depends on the development of certain components of intercellular substance, frequencies of individual types of cells and appearance of specific cellular element in it.

Animals↗
PubMed1997

[Structures and functions of animal toxins].

This brief review is devoted to the presentation of the major toxic proteins found in venoms of animals from five phyla. It is shown that various groups of venomous animals, including scorpions and snakes, produce toxins that exert different functions although they adopt a similar structure, suggesting that these toxins result from a divergent evolution. On the opposite, it is shown that toxins produced by animals from different phyla can exert similar functions even though they adopt unrelated structures, suggesting a convergent evolution. Finally, this review describes, at the molecular level, the functional and structural properties, including the dynamical characteristics, of a snake toxin which binds to the peripheral nicotinic acetylcholine receptor.

Animals↗