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Cyclotetrapeptides and cyclopentapeptides: occurrence and synthesis*
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Personen und Körperschaften: | , |
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Titel: |
Cyclotetrapeptides and cyclopentapeptides: occurrence and synthesis* |
In: | The Journal of Peptide Research, 49, 1997, 1, S. 67-73 |
veröffentlicht: |
Wiley
|
Umfang: | 67-73 |
ISSN: |
1397-002X |
DOI: | 10.1111/j.1399-3011.1997.tb01122.x |
Zusammenfassung: | <jats:p>The structures reported for the three cancerostatic all‐<jats:sc>l</jats:sc>‐cyclotetrapeptides cyclo(Pro‐Leu)<jats:sub>2</jats:sub>, cyclo(Pro‐Val)<jats:sub>2</jats:sub> and cyclo(Pro‐Phe)<jats:sub>2</jats:sub> isolated from a tunicate seem questionable. The synthetic compounds claimed to be identical to the naturally occurring cyclotetrapeptides are in fact not cyclotetrapeptides but rather cyclooctapeptides.</jats:p><jats:p>We have not been able to prepare the tyrosinase inhibitor cyclo(Pro‐Val‐Pro‐Tyr). Ring closure of H‐Pro‐Val‐Pro‐Tyr‐OC<jats:sub>6</jats:sub>F<jats:sub>5</jats:sub> gave rise to 31% of cyclo(Pro‐Val‐Pro‐<jats:sc>d</jats:sc>‐Tyr). The same product was obtained in 53% yield from H‐Pro‐Val‐Pro‐<jats:sc>d</jats:sc>‐Tyr‐oc<jats:sub>6</jats:sub>F<jats:sub>5</jats:sub>.</jats:p><jats:p>For the ring closure to the all‐<jats:sc>l</jats:sc>‐cyclopentapeptide cyclo(Pro‐Ala‐Ala‐Phe‐Leu), all ring closure positions have been investigated. The reaction at the nitrogen atom of leucine leads to 21% of the all‐<jats:sc>l</jats:sc>‐cyclopentapeptide. Dimers or mixtures of monomers and dimers result from reaction at all other positions. © Munksgaard 1997.</jats:p> |
Format: | E-Article |
Quelle: | Wiley (CrossRef) |
Sprache: | Englisch |