NOVEL PHYSIOLOGICALLY ACTIVE PEPTIDE AND CALCIUM METABOLISM-REGULATING AGENT COMPRISING SAID PEPTIDE AS EFFECTIVE INGREDIENT

A novel physiologically active peptide having the following amino acid sequence: (see above formula) wherein X1 stands for Ser-Thr or Thr-Ser; X2 stands for Met, Gly, Ala, Val, n-Val, Pro, Leu or n-Leu; X3 stands for Glu; X4 stands for Leu-Gln-Thr, Gln-Thr, Leu or Gly-Gln-Thr; X5 stands for Val-Gly-Ala or Ser-Gly-Thr; R stands for H, NH2, N-acyl or N-alkyl; X6 stands for CO-NH or NH-CO; X7 stands for an amino acid sequence at the 2- to 6-positions of native calcitonin, and having 0 to 6 amino acids, X8 stands for an amino acid sequence at the 8- to 32-positions of native calcitonin; and each of n1 and n2 is an integer of 0 to 19 and n1 + n2 is 1 to 20, or a pharmacologically acceptable salt thereof, and a calcium metabolism-regulating agent comprising, as an effective ingredient, the above-mentioned peptide or salt, and a customary pharmaceutical carrier.