Abstract: New hypocalcaemic peptides are disclosed of the formula ##STR1## wherein X represents H for the replacement of the N alpha amino group or acyl groups for the acylation of the N alpha amino group, the N-alpha amino group. The acyl groups are carboxylic acids especially formic, acetic, propionic, buteric, valeric, hexanoic, heptanoic, octanoic, and nonanoic acids or their respective isomers, L-lactic acid and the half amides of malonic, succinic, glutaric and adipic acids. Y is L-valine, glycine, L-methionine, L-alanine, L-leucine or L-isoleucine.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which do not have a leucine in position 19, a glutamine in position 20, or a threonine in position 21. All three amino acids are omitted. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which do not have a leucine in position 19, a glutamine in position 20, a threonine in position 21, and a tyrosine in position 22. All four amino acids are omitted. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New hypocalcaemic peptides are disclosed of the formula ##STR1## wherein X represents acyl groups for the acylation of the N alpha-amino group and the radicals of carboxylic acids especially of formic, acetic, propionic, buteric, valeric, hexanoic, heptanoic, octanoic, and nonanoic acids along with all their respective isomers. We also wish to include L-lactic acid along with the half amides of malonic, succinic, glutaric and adipic acids.

Abstract: New peptides are disclosed which have biological activity of the same type as the known calcitonins and which have a glycine at position 8 instead of the natural valine found in that position. In addition these new peptides do not have a leucine in position 19. The position 19 leucine is omitted. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which do not have a leucine in position 19 or a glutamine in position 20. Both amino acids are omitted. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which do not have a disulfide bond connecting the cysteines at positions one and seven. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin partially protected peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which have an S-acetamidomethyl cysteine at one and an alanine at seven, or an alanine at one and an S-acetamidomethyl cysteine at seven. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin-type peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which do not have a leucine in position 19. The position 19 leucine is omitted. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins; which have a serine in position 6 while the position 19 leucine is omitted. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which do not have a serine in position 2 nor an asparagine in position 3. Both serine 2 and asparagine 3 are omitted. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which do not have cysteines at positions one and seven. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin-type peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which have an methionine in position 8 instead of the natural valine found in that position. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and do not have an amino group on cysteine one and also are substitution analogs of the natural calcitonins. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which do not have a leucine in position 4. The position 4 leucine is omitted. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which do not have a threonine in position 21. The position 21 threonine is omitted. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which have a shorter amino acid chain than natural calcitonins and are also substitution analogs of the natural calcitonins. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which do not have a serine in position 13. The position 13 serine is omitted. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which have a shorter amino acid chain than natural calcitonins and are also substitution analogs of the natural calcitonins. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.

Abstract: New peptides are disclosed which have biological activity of the same type as known calcitonins and which have a shorter amino acid chain than natural calcitonins and are also substitution analogs of the natural calcitonins. Also resin peptides are disclosed which may be converted to peptides having such biological activity; and processes for producing said resin peptides and said calcitonin peptides.