Amanita phalloides peptides

Phalloidin and phallacidin are cyclic peptides from the mushroom Amanita phalloides that stabilize F-actin. Phalloidin binds to residues 114-118 of an actin protomere and blocks nucleotide exchange without interfering with nucleotide hydrolysis. It enhances the rate of nucleation as well as that of elongation. It slowly penetrates the cell membrane and is used for immunocytochemical localization of F-actin. 

Poisoning and sometimes death from eating (unidentified) mushrooms is well known. In particular, Amanita sp. are particularly dangerous, with much emphasis on the death cap fungus , Amanita phalloides.24 The best known toxins are the amatoxins and phallotoxins, which are complex, bicyclic peptides. An unusual feature relates to sulfur a tryptophan (or substituted tryptophan) unit is linked to a cysteine sulfur at the carbon atom next to the NH group of the pyrrole ring, forming the unit, -CH2-S-C(NH)=C, e.g. in... 

Several experimental approaches can be employed to determine the pool sizes of polymerised and non-polymerised actin. Firstly, the enzyme DNAse I is inhibited by monomeric (G) actin, but not by polymerised (F) actin. Secondly, polymerised actin can be directly visualised by use of fluorescent derivatives of phalloidin, a cyclic peptide isolated from the toadstool Amanita phalloides that selectively binds to polymerised actin with high affinity. 

Labeled phallotoxines (phalloidins) The bicyclic peptides isolated from Amanita phalloides mushroom bind selectively to F-actin in nanomolar concentrations. They have advantages over antibodies for actin labeling... 

H Fungi - Amanita phalloides and Agaricus phalloides Cyanobacteria -Lyngbya majuscula Phalloidin, phallicidin, and amanitin - toxic peptides Majusculamide D - cytotoxic peptide Microcolin A - peptide with immunosuppressive, antileukemic and protein kinase C inhibitory activity 242... 

Other species of amanita are among the deadliest fungi known. Polypeptide-like toxins in Amanita phalloides, or death cup, can prove fatal or at the very least can cause permanent liver and kidney damage. These mushrooms are common in the temperate climates of Europe and North America. They are responsible for the majority of what is called "slow" mushroom poisoning in the U.S. In fact, it was only a few years ago that the local newspaper reported a case of amanita poisoning within SLO county. Mushroom poisoning is known as mycetism. In addition the amanita also contain bufotenine which has CNS effects. See the ASIDE which discusses the peptide poisons. 

The poisonous components of the most deadly mushroom Amanita phalloides (the Death Cap) are bicyclic heptapeptides which have an additional covalent bond that connects the ( -sulfur atom of an l-cysteine residue with the carbon atom in position 2 of the indole ring of the L-tryptophan. Phalloidin (or phalloidine) is the most abundant member of a whole family of related cyclic heptapeptides called phallotoxins (for a review, see Wieland1 1). These poisonous peptides, therefore, contain a cross-linking moiety consisting of L-tryptophan coupled to L-cysteine, designated tryptathionine (1), alternatively called 5-(trypto-phan-2-yl)cysteine or 2-(L-3-alanylsulfenyl)-L-tryptophan (Scheme 1). 

The phallotoxins 106, e.g. phalloidin, and the amatoxins 107, e.g. a-amanitin, produced by Amanita phalloides or death cup, are among the best-known peptide poisons 233). 

Chemical-induced liver injury is encountered in a variety of circumstances. Some natural toxins such as the peptides of Amanita phalloides, the pyrrolizidine alkaloids, the toxin of the cycad nut, and other plant toxins are hazards posed by the environment. Some mycotoxins are ingested unknowingly because of feed contamination due to climatic conditions favorable to fungal growth. Other circumstances of exposure to hepatotoxins include contamination of water supply with cyanobacterial toxins, which led to the tragic death of 60 patients in a hemodialysis clinic in Brazil in 1996 (Jochimsen et al, 1998). 

It also should be noted that within the genus Amanita there exist several species of deadly mushrooms. They are among the small number of mushroom species the ingestion of which can prove fatal. These species include Amanita phalloides and Amanita viA, both of which contain small peptides called amanitins that inactivate RNA polymerase and cause irreversible damage to liver function. 

N-Methylmorpholine [1, 690]. In the mixed anhydride synthesis of peptides, N-methylmorpholine was found to give little or no racemization in cases where triethylamine, the commonly used base, caused extensive racemization.1 Trimethyl-amine, a potent racemizer, can be used successfully if an excess is avoided. N-Methylmorpholine was used by Wieland2 in the synthesis of antamanide, a cyclic decapeptide of Amanita phalloides, which counteracts the lethal action of Amanita toxins. 

The extremely poisonous green mushroom Amanita phalloides contains a number of cyclic peptides classified as phallotoxins (heptapeptides), ama-toxins (octapeptides), and a decapeptide antagonist called antamanide (Wieland and Wieland, 1972). Crystal structure analyses have been completed on jS-amanitin, on antamanide, and on a biologically active analog, both com-plexed and uncomplexed. 

Bavaria, where in 1937 Ulrich Wieland and Feodor Lynen were able to crystallize for the first time a substance which was called phalloidin that rapidly killed mice after intraperitoneal application. Three years later Heinrich Wieland and Rudolf Hallermayer crystallized from Amanita phalloides extracts a second toxin, amanitin , which with smaller doses killed the experimental animals only after several days Uke a deadly dish of A, phalloides kills humans. Bernhard Witkop (Plate 49) 1940 in H. Wieland s laboratory recognized that phalloidin is a peptide and isolated a new imino acid, allo-hydroxyproline. Then the Second World War interrupted Amanita research which was resumed in Heidelberg by one of the present authors only ten years later and continued in Mainz, Frankfurt and again in Heidelberg through the following decades. 

Phallotoxins and Virotoxins. - Molecular Pathology of the Amanita Peptides. -Non-Toxic Peptides from Amanita phalloides. -Phallolysin. - Retrospectives and Outlook. -References. - Subject Index. 

The conformational features of ring-structure, hypercyclization, the presence of N-methyl amino acids and other imino acidsare not the attributes of peptide antibiotics only. The toxic principles of Amanita phalloides, phalloidin and amanitin exhibit similar characteristics and the more recently discovered and synthesized component of the same fungus antaminid (III), a peptide which can antagonize the toxic effects of amanitin, is also cyclic. In this particular case no D-amino... 

The poison present in the fungus most commonly responsible for cases of poisoning. Amanita phalloides, is a peptide known as phalloidin. On hydrolysis, it gives cystine and alanine, but, in addition, allohydroxy-L-proline, a diastereoisomer of the form of proline found in proteins. 

The most important compounds of this group of fungi toxins are the cyclic peptides amatoxins or amanita toxins (10-202) and phaUo-toxins (10-203) of the death cap (Amanita phalloides, Amanitaceae) that cause the phaUoidin poisoning. The main toxin is phaUoidin... 

A cyclic peptide that neutralizes the effect of phalline B, a toxin (also a cyclic peptide) present in the deadly mushroom Amanita phalloides. 

The green death cap Amanita phalloides produces two families of toxic peptides, the amatoxins and the phallotoxins. Amatoxins are by far the more dangerous toxins and account for all fatalities occurring in human mushroom poisoning. 

Among the homodetic, polycyclic, biologically-active tryptophan peptides, the toxins of the Amanita phalloides represent a special case [see reference 427) and 349) for a review]. In fact, the poisonous components of this deathcap, the phallotoxins and amatoxins (Fig. 9), both contain a cycloheptapeptide structure with an additional intramolecular covalent bond connecting the p-sulfur atom of a L-cysteine residue with the carbon atom in position 2 of the indole ring of a L-tryptophan residue. In the amatoxins the thioether bridge is oxidized to the sulfoxide (Fig. 9). 

The reaction of hexahydropyrroloindole (HPI) (46) with thiols to give the corresponding 2-thioether-tryptophan compounds has been further investigated (464). Reaction of cysteine with HPI (1.2 equiv) in 25% tri-fluoroacetic acid produces quantitatively tryptathionine, an amino acid contained in the toxic peptides of Amanita phalloides (see Section VI.2.4.). Reduced ribonuclease, a protein containing 8 cysteine residues per molecule, was treated with HPI, and the modified protein purified by gel filtration. The completeness of the reaction was confirmed by hydrolysis with /7-toluenesulfonic acid (233) and analysis of the hydrolyzate. A value of 7.6 (theory 8) residues per mole of protein of oxindolylalanine, the product of hydrolysis of the tryptathionine residues (431) (see Section III.4.2.), was obtained. This new reaction of cysteine residues should be of value in peptide synthesis, providing a simple method for linking tryptophan and cysteine as a basic step in the chemical synthesis of the peptides of Amanita phalloides. 

The history of the major achievements concerning the isolation, structure elucidation, chemistry, and biological activity of the cyclic peptide principles of A. phalloides was comprehensively covered mainly by T. Wieland, a man of great merit particularly in this branch of natural products research. He dealt with the subject in several review articles 10,87,94,98-101) and more recently in an excellent book on the peptides of poisonous Amanita mushrooms 86). The number of references cited in the book exceeded 750, which gives a rough idea of the proportion of research carried out by chemists on this topic. The scope of the present chapter enables us only to summarize briefly the final results of these interesting studies. 

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