Comparison of black coral skeleton and insect cuticle by a combination of carbon-13 NMR and chemical analyses.
Cross-polarization, magic-angle spinning 13C NMR spectra of skeletal components of individual colonies of the New Zealand black coral, Antipathes fiordensis, have a marked similarity to spectra of the sclerotized exoskeleton of the adult tobacco hornworm, Manduca sexta. NMR analysis estimates the organic content of the load-bearing skeletal base of A. fiordensis as 70% protein, 10% chitin, 15% diphenol, and 5% lipid by weight, and that of M. Sexta moth cuticle as 60% protein, 20% chitin, 15% diphenol, and 5% lipid. The younger pinnules or tips of A. fiordensis are less than 3% diphenol by weight. The only diphenols extracted from coral skeleton by hydrochloric acid are 3-(3,4-dihydroxyphenyl)-DL-alanine (DOPA) and 3,4-dihydroxybenzaldehyde (DOBAL), while the predominant diphenols in acid extracts of insect cuticles are N-acyldopamines. More DOPA is found in the base than in the tips of A. fiordensis and it appears to be a peptidyl component of coral skeletal protein. The oxidation of DOPA and DOBAL to quinones may provide mechanical stabilization of the coral skeleton by cross-linking of structural proteins to other proteins or to chitin.
Department of Chemistry, Washington University, St. Louis, Missouri 63130.
S M
SM
Holl
J
J
Schaefer
W M
WM
Goldberg
K J
KJ
Kramer
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TD
Morgan
T L
TL
Hopkins
D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D001823:Body Composition; D002247:Carbon Isotopes; D003063:Cnidaria / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D009036:Moths / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry; D012867:Skin / Q000737:chemistry; D014020:Tissue Extracts / Q000737:chemistry*
D000596:Amino Acids; D002247:Carbon Isotopes; D008055:Lipids; D011506:Proteins; D014020:Tissue Extracts