From Anthopleura elegantissima and from Hydra attenuata, a morphogenetic peptide-the head activator-was isolated in pure form. The sequence of the head activator was established by enzymatic and by chemical degradation of the whole peptide or fragments thereof and subsequent analysis of the amino acids by micromethods. The head activator from both sources was identical and has the sequence:<pGlu-Pro-Pro-Gly-Gly-Ser-Lys-Val-Ile-Leu-Phe.
Department of Zoophysiology, University of Heidelberg, Max-Planck-Institute for Medical Research, Jahnstrasse 29, 6900 Heidelberg, Federal Republic of Germany.
