A method for chemically modifying a peptide, derivative or analogue thereof is described. The method comprises contacting a peptide, derivative or analogue thereof with a fluoro-heteroaromatic compound to activate the peptide, derivative or analogue thereof. The activated peptide, derivative or analogue thereof is then contacted with a nucleophile or base to create a chemically modified peptide, derivative or analogue thereof.

The present invention provides a method for inexpensively and efficiently synthesizing polypeptide compounds comprising various amino acids. The method involves (i) inducing an amide formation reaction between the carboxyl group on the right side in the formula of the amino acid or peptide compound represented by formula (R1) and the amino group on the left side in the formula of the amino acid ester or peptide ester compound represented by formula (R2) in the presence of an aluminum compound represented by formula (A) to obtain a peptide compound represented by formula (P1) (the definitions of the reference signs in the formula are as presented in the description).

##STR00001##

A method for preparing a cyclic peptide, derivative or analogue thereof is described. The method comprises contacting a peptide, derivative or analogue thereof with a fluoro-heteroaromatic compound to cyclise the peptide, derivative or analogue thereof.

A method for chemically modifying a peptide, derivative or analogue thereof is described. The method comprises contacting a peptide, derivative or analogue thereof with a fluoro-heteroaromatic compound to activate the peptide, derivative or analogue thereof. The activated peptide, derivative or analogue thereof is then contacted with a nucleophile or base to create a chemically modified peptide, derivative or analogue thereof.

Provided is a method that prevents decreases in solubility in an organic solvent when elongating a peptide chain by a peptide coupling reaction and improves the reactivity of a peptide chain and the operability in a purification process. The method makes it possible to obtain a polypeptide compound represented by formula (P1) by performing amide formation reaction of the carboxyl group on the right side of the amino acid or the peptide compound in formula (R1) with the amino group on the left side of the amino acid or the peptide ester compound in formula (R2) in which the terminal carboxyl group is protected by a silicon-containing hydrophobic substituent TAG(Si).

##STR00001##

Compositions and methods for optically-verified, sequence-controlled polymer synthesis are described.

This method comprises: (i) a step for forming an amide bond between a T.sup.a-substituted carboxyl group located on the right side in formula (R1) in an N-terminal-protected amino acid or peptide ester represented by formula (R1) and an amino group amino group located on the left side in formula (R2) in an amino acid or peptide represented by formula (R2) or an ester compound thereof to produce an N-terminal-protected peptide represented by formula (S1); (ii) a step for deprotecting the N-terminal of the compound represented by formula (S1) produced in step (i) to produce a peptide compound represented by formula (P1); and (iii) a step for repeatedly performing the steps (i) and (ii) using the compound represented by formula (P1) produced in step (ii) as the compound represented by formula (R2) in step (i) to extend a peptide chain by amidation. In formulae (R1), (R2), (S1) and (P1), each symbol is as defined in the claims.

##STR00001##

The symbols in formulae (R1), (R2), (S1), and (P1) each have the meanings defined in the claims.

The present disclosure relates to the technical field of antibody engineering, and specifically provides a polypeptide fragment thyroid hormone receptor betal (THRB)-CVD20, and a polyclonal antibody prepared using the same and use thereof. The present disclosure provides a polypeptide fragment THRB-CVD20, wherein the polypeptide fragment has an amino acid sequence shown in SEQ ID NO: 1. The present disclosure further provides a preparation method of the polypeptide fragment and a polyclonal antibody prepared using the polypeptide fragment. In the present disclosure, the polyclonal antibody can accurately identify target cells due to high sensitivity and specificity, and can be further used to identify, identify, and screen the THRB.