title: Structure-activity relations of fulicin, a peptide containing a D-amino acid residue.
abstract: Structure-activity relations of fulicin (H-Phe-D-Asn-Glu-Phe-Val-NH2) isolated from the ganglia of a pulmonate mollusc Achatina fulica were investigated on the contraction of penis retractor muscle of this snail. The contraction-enhancing activity of fulicin was reduced to about 1/3000 when D-Asn2 was replaced by L-Asn, whereas substitution of the other D-amino acid for D-Asn2 showed no significant reduction of the activity. On the contrary, if a D-amino acid was introduced into any position other than position 2 the activity was reduced remarkably. The presence of Glu3 and five amino acid residues as a whole were also required for activity.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017952:Ganglia, Invertebrate / Q000737:chemistry*; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects; D009479:Neuropeptides / Q000737:chemistry* / Q000494:pharmacology; D012908:Snails / Q000187:drug effects*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
chemical_list: D009479:Neuropeptides; C070040:fulicin