Peptides of rye ergot

There are now five known peptides extracted from rye ergot, and they are classified into 2 groups (Table XII). They are all heteromeric polycyclic peptides, containing one molecule of lysergic acid (316,317). 

Their structures have been carefully studied by Stoll et al. (564,565,566, 568,569) the details cannot be discussed here. Stoll, Hofmann, and Petrzilka (566) finally succeeded in establishing the complete structure of these peptides (Table XII). 

All contain L-proline, as orthocarbonic acid, one of whose hydroxyl groups is linked in a lactone bond with the hydroxyl group of hydroxyal-anine in peptides of the ergotamine family or with the hydroxyvaline in the peptides of the ergotoxin family. Another hydroxyl group of orthocarbonic acid in linked in a lactam bond, and a third is free. Proline participates in a cyclol structure, the existence of which Avas experimentally demonstrated for the first time by these workers. Thus the carbon of proline s carboxylic group is asymmetric. The other amino acids (phenylalanine, leucine, and valine), are in the l form. 

Photographs of the crystalline forms of these peptides and a description of a series of their derivatives, particularly the di(p-toluyl)-l-tar-trates can be found in the work of Stoll and Hofmann (562). 

All the peptides of rye ergot are levorotatory (Table XII). On heating of methanol solutions, or by alcoholic sodium hydroxide treatment, the 

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In addition to linear peptides, one can envisage the existence of cyclic peptides in which there is neither an initial nor terminal amino acid and for which the number of peptide bonds equals the number of amino acids. Of course, one can also postulate the existence of partially cyclic peptides, forming sigma-shaped chains (amino acid is internally linked in the peptide. Therefore, it is possible to have partially cyclic peptides possessing either a terminal (6 ° ) or an initial amino acid (h,n9) Certain peptides possess other structures, e.g., bicyclic and polycyclic, owing to the presence of nonpeptide linkages between amino acids, in addition to the characteristic a-peptide bond. Examples of such structures are penicillins, peptides of rye ergot. 

As a theoretical alternative seems a method according that strains, which produce ergot alkaloids saprophytically, are preserved as sclerotia formed on an infected, proper host plant, e.g. rye for strains of the species Claviceps purpurea. Viability of the sclerotia when stored in refrigerator is several years. Questions of contingent changes of strain prodnction characteristics due to alternation of saprophytic and parasitic phases were treated by Breuel and Brann (1981), and Breuel et al. (1982). During surface stationary production of peptide alkaloids it was possible to keep production strain in the form of dried mycelinm at 4°C for 3 years without any influence to prodnction capability (Kybal, Malinka, unpublished results). 

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