Chemical ligation of unprotected peptide segments has become the most practical method for the total synthesis of native proteins. This technique allows the preparation of a wide range of proteins, leading to the elucidation of gene function, discovery of novel biology, and determination of new three-dimensional protein structures by NMR and X-ray crystallography. Chemical protein synthesis provides facile access to novel analogs, offering insights into the molecular basis of protein function. It has also enabled the systematic development of proteins with enhanced potency and specificity as therapeutic agents. The method involves the use of unique, mutually reactive functional groups to enable the ligation of completely unprotected peptide segments. This approach allows the synthesis of large polypeptide chains with a native peptide bond at the ligation site. The native chemical ligation method, which uses reversible thiol/thioester exchange, enables the formation of a native amide bond. This method has been used to synthesize a variety of proteins, including HIV-1 protease, covalent heterodimers of transcription factors, and receptor mimetics. The native chemical ligation method has been shown to produce proteins with high yield and purity, and to allow the preparation of unnatural analogs for the study of protein structure and function. The method has also been used to study protein splicing and conformationally assisted ligation, which involve the post-translational processing of proteins. The ability to fold synthetic proteins efficiently in vitro has been demonstrated, with many proteins showing correct tertiary structure and biological activity. The synthesis of native proteins by chemical ligation has enabled the preparation of a wide range of proteins, including small, Cys-rich proteins and multidomain proteins. The method has been used to synthesize proteins such as AOP-RANTES, a potent anti-HIV molecule, and NNY-RANTES, which is the most potent known anti-HIV compound. The method has also been used to study the structure and function of proteins, including the HIV-1 protease and other enzymes. Chemical protein synthesis has provided a convenient and general route to site-specific modification of proteins, allowing the introduction of non-coded amino acids and precise covalent modifications. The method has also been used to incorporate fluorescent tags and affinity tags into proteins, enabling the study of protein-protein interactions and the development of new therapeutic agents. The ability to synthesize proteins directly from gene sequence data has enabled rapid access to functional wild-type protein molecules, facilitating the study of protein structure and function. The method has also been used in structural biology to determine the three-dimensional structures of proteins using NMR and X-ray crystallography.Chemical ligation of unprotected peptide segments has become the most practical method for the total synthesis of native proteins. This technique allows the preparation of a wide range of proteins, leading to the elucidation of gene function, discovery of novel biology, and determination of new three-dimensional protein structures by NMR and X-ray crystallography. Chemical protein synthesis provides facile access to novel analogs, offering insights into the molecular basis of protein function. It has also enabled the systematic development of proteins with enhanced potency and specificity as therapeutic agents. The method involves the use of unique, mutually reactive functional groups to enable the ligation of completely unprotected peptide segments. This approach allows the synthesis of large polypeptide chains with a native peptide bond at the ligation site. The native chemical ligation method, which uses reversible thiol/thioester exchange, enables the formation of a native amide bond. This method has been used to synthesize a variety of proteins, including HIV-1 protease, covalent heterodimers of transcription factors, and receptor mimetics. The native chemical ligation method has been shown to produce proteins with high yield and purity, and to allow the preparation of unnatural analogs for the study of protein structure and function. The method has also been used to study protein splicing and conformationally assisted ligation, which involve the post-translational processing of proteins. The ability to fold synthetic proteins efficiently in vitro has been demonstrated, with many proteins showing correct tertiary structure and biological activity. The synthesis of native proteins by chemical ligation has enabled the preparation of a wide range of proteins, including small, Cys-rich proteins and multidomain proteins. The method has been used to synthesize proteins such as AOP-RANTES, a potent anti-HIV molecule, and NNY-RANTES, which is the most potent known anti-HIV compound. The method has also been used to study the structure and function of proteins, including the HIV-1 protease and other enzymes. Chemical protein synthesis has provided a convenient and general route to site-specific modification of proteins, allowing the introduction of non-coded amino acids and precise covalent modifications. The method has also been used to incorporate fluorescent tags and affinity tags into proteins, enabling the study of protein-protein interactions and the development of new therapeutic agents. The ability to synthesize proteins directly from gene sequence data has enabled rapid access to functional wild-type protein molecules, facilitating the study of protein structure and function. The method has also been used in structural biology to determine the three-dimensional structures of proteins using NMR and X-ray crystallography.