Lanthionine

Fig. 9. Stmcture of nisin where Dha = dehydroalanine Dhb = dehydrobutyrine Abu = a-aminobutyric acid Ala-S-Ala = me50-lanthionine and Abu-S-Ala = t/ireo-methyllanthionine. The first amino acid residue (Ala or Abu) of the lanthionine or methyUanthionine is a D residue all other amino...

Dialkyl esters of cystine (39) and lanthionine (40) undergo a surprising thermolysis reaction at between 25 C and 80 °C to afford cis and trans methyl 2-methylthiazolidine-2,4-dicarboxylates (43) in protic solvents. A two stage process is proposed for this transformation. An initial i-elimination reaction gives the thiol (41) and the enamine (42). Thiol addition to the imine tautomer of (42) is then followed by loss of ammonia and an intramolecular cyclisation to give (43) <96CC843>. 

S., Simultaneous determination of urinary cystathionine, lanthionine, S-(2-aminoethyl)-L-cysteine and their cyclic compounds using liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization, /. Chromatogr. B, 698, 301, 1997. 

G. Melacini, Q. Zhu, G. Osapay, M. Goodman, A Refined Model for the Somatostatin Pharmacophore Conformational Analysis of Lanthionine-Sandostatin Analogs , J. Med. Chem. 1997, 40, 2252-2258. 

Figure 3 The two-step process resulting in the formation of lanthionines from Ser and Cys and methyllanthionines from Thr and Cys.

Figure 15 Structures of lantibiotics containing a conserved methyllanthionine ring displayed in red. The glutamate that is essential for both mersacidin and haloduracin antimicrobial activity is shown in blue. The structure of plantaricin C has not yet been unambiguously determined and the proposed structure is shown. The stereochemistry of the lanthionine between residues 7 and 27 is not known.

The regulation of bacteriocin synthesis by PPs goes back to mid-1990s when it was shown that the Class II bacteriocins (nonmodified heat-stable bacteriocins) as well as Class I bacteriocins most often referred to as lantibiotics (post-translatory modified containing most frequently lanthionine, methyl-lanthionine, dehydrated serine, and threonine) were regulated by small ribosomally synthesized peptides either resembling a peptide... 

The majority of bid mutants are unable to produce and secrete SapB. Sap B is able to reduce water surface tension considerably. Purified Sap B, SapT, lanthionine-containing peptide from S. tendae and SC3 hydrophobin of Schizophylum communae, added to the medium, restore the ability of bid mutants to raise aerial hyphae. 

Kodani S, SapT, a lanthionine-containing peptide involved in aerial hyphae formation in the streptomycetes, Mol Microbiol 58 1368—1380, 2005. 

I. Inorganic sulfur compounds containing another (usually more electropositive) element. When the other element is an alkali or alkaline earth, the sulfide is ionic in character. Metal sulfides often have unusual stoichiometries. Examples of sulfides include H2S, Na2S, FeS, and HgS. 2. Organic sulfides are also referred to as thioethers and have the general structure R—S—R. Biochemical examples of sulfides include methionine, cystathionine, and djenkolic acid. If the two R groups are identical, the substance can be referred to as a symmetrical sulfide (biological examples of which are lanthionine and homo-lanthionine). 

Lanthionine (Lan) (1) is a naturally-occurring, but relatively rare dicarboxylic diamino acid, which until recently, was largely ignored. The amino acid was initially identified as an artifact in amino acid analysis of wool hydrolyzates111 which later turned out to be a result of the alkaline hydrolysis procedure used. Subsequently, it was discovered that a novel class of bacterial-derived peptide antibiotics also contained lanthionine and the closely related amino acid 3-methyllanthionine (MeLan) (2) (Scheme 1). 

Scheme 1 The Structures of the Naturally Occurring Thioether Amino Acids meso-Lanthionine and threo-Methyllanthionine and Common Abbreviations within the Peptide Chain, Alanine and Threonine Denote the Amino Acid Core Structures Linked to the Sulfur Atom through the Side Chain...

Lanthionine is a dicarboxylic diamino acid possessing two stereocenters. However, because of the symmetry of the molecule there exist only three stereoisomers. Thus, with respect to lanthionine stereochemistry, one must differentiate between the 2/ ,6/ -lanthionine (L-lan-thionine), 25,65-lanthionine (D-lanthionine) and 25,67 -lanthionine (meso-lanthionine, d,l-lanthionine) (1) the latter is the naturally occurring stereoisomer of lanthionine isolated from lantibiotics. However, care must be taken when determining and assigning the stereochemistry of lanthionine residues present within peptide sequences. For naturally occurring lanthionine peptides the sulfide amino acid Lan within the peptide is no longer symmetrical and, in the majority of cases, it has been shown to be present as 25,67 -lan-thionine. 

Considering the stereochemistry and nomenclature of lanthionines, the variety may become somewhat confusing. Here, we have endeavored to restrict ourselves to the d,l-nomenclature however, because of the diversity of nomenclatures found in the literature, this is not always possible. In this context, it has to be noted, that L-cysteine is (27 )-cysteine... 

Synthesis of Lanthionine Derivatives by Desulfurization of Cystine Compounds... 

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