Abstract: A peptide complex including: a peptide; and a cell-membrane-permeability-imparting group introduced into the peptide, wherein the cell-membrane-permeability-imparting group includes a dendritic structure including four or more branches, and at least four branches of the four or more branches include basic functional groups at ends thereof.

Abstract: Novel cell-penetrating peptides are provided, which are excellent in cell membrane permeability. The cell-penetrating peptide or salt thereof according to the present invention is characterized in comprising the sequence represented by formula (I) or the formula (II) as follows: X-(A-B-C)l-(D)m-(Arg)n (Formula I) or X-(Arg)n-(D)m-(A-B-C)l (Formula II), wherein X is a physiologically active peptide, A, B and C are aliphatic amino acids, D is an arbitrary amino acid, l is an integer of 1 or more and 4 or less, m is an integer of 0 or more and 5 or less, when l is 1, n is an integer of 8 or more, when l is 2, n is an integer of 6 or more, when l is 3, n is an integer of 4 or more, when l is 4, n is an integer of 4 or more.

Abstract: A method for producing a ribosome display complex includes obtaining a ribosome complex including an unmodified polypeptide chain, an mRNA molecule and a ribosome by initiating translation of the mRNA molecule in a cell-free peptide synthesis system including the ribosome, and modifying the unmodified polypeptide chain by reacting a side chain reactive functional group in the unmodified polypeptide chain with a modifying reagent to produce a ribosome display complex including a modified polypeptide chain, the mRNA molecule and the ribosome. The unmodified polypeptide chain includes at least one reactive amino acid residue selected from the group consisting of a cysteine residue, a lysine residue, a histidine residue and a tryptophan residue. The at least one reactive amino acid residue includes the side chain reactive functional group, and the mRNA molecule includes a base sequence encoding an amino acid sequence of the polypeptide chain.

Abstract: A method for producing a ribosome display complex includes obtaining a ribosome complex including an unmodified polypeptide chain, an mRNA molecule and a ribosome by initiating translation of the mRNA molecule in a cell-free peptide synthesis system including the ribosome, and modifying the unmodified polypeptide chain by reacting a side chain reactive functional group in the unmodified polypeptide chain with a modifying reagent to produce a ribosome display complex including a modified polypeptide chain, the mRNA molecule and the ribosome. The unmodified polypeptide chain includes at least one reactive amino acid residue selected from the group consisting of a cysteine residue, a lysine residue, a histidine residue and a tryptophan residue. The at least one reactive amino acid residue includes the side chain reactive functional group, and the mRNA molecule includes a base sequence encoding an amino acid sequence of the polypeptide chain.

Abstract: A method for producing a purified peptide from a supported crude peptide having a support and a first peptide chain bonded to the support at the C-terminus. The method includes: introducing a linker and a hydrophilic unit to an amino group of the first peptide chain of the supported crude peptide; cleaving a bond between the first peptide chain and the support before or after at least one of the linker and the hydrophilic unit is introduced to the amino group of the first peptide chain such that a support-free hydrophilized peptide is obtained; treating the support-free hydrophilized peptide by liquid chromatography; and cleaving a bond between the linker and the first peptide chain in the support-free hydrophilized peptide by chemical treatment after the liquid chromatography treatment such that a peptide including the first peptide chain is obtained.