1. Biotin (countable and uncountable, plural Biotins) (biochemistry) A sulfur-containing member of the vitamin B complex, 5-[(3aS,4S,6aR)-2-oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl]pentanoic acid, found in liver, egg yolk, milk and yeast, essential to the activity of multiple enzyme systems

2. A peptide having formula (I) wherein Mpa is 3-mercaptopropionic acid residue (-S-CH¿2?-CH¿2?-CO-); X is D-tryptophan (D-Trp) or $g(b)-(2-Naphtyl)-D-alanine (D-Nal); Ile is isoleucine; Y is alloisoleucine (alloIle) or (S)-2-Amino-3-ethyl-pentanoic acid (Ala($g(b)-Et¿2?)) ; Asn is asparagine; $g(a)-Abu is $g(a)-aminobutyric acid residue (II) and N$g(a)MeOrn is N$g(a)-methyl-ornithine, is disclosed.