Abstract: The invention provides methods of producing functional split inteins having small N-intein and/or small C-intein. Using these split inteins with their protein trans-splicing and cleavage activities, we provide new and more effective methods of manipulating proteins. They include site-specific addition of synthetic peptides at protein's terminal and internal locations, ligation of synthetic and/or expressed polypeptides, controllable cyclization of synthetic and/or expressed polypeptides, and controllable cleavages of recombinant proteins. These methods have numerous utilities including but not limited to protein fluorescence labeling, fixation on microchips, site-specific PEGylation, and linkage with pharmaceutical molecules.

Abstract: The invention provides methods of producing functional split inteins having small N-intein and/or small C-intein. Using these split inteins with their protein trans-splicing and cleavage activities, we provide new and more effective methods of manipulating proteins. They include site-specific addition of synthetic peptides at protein's terminal and internal locations, ligation of synthetic and/or expressed polypeptides, controllable cyclization of synthetic and/or expressed polypeptides, and controllable cleavages of recombinant proteins. These methods have numerous utilities including but not limited to protein fluorescence labeling, fixation on microchips, site-specific PEGylation, and linkage with pharmaceutical molecules.

Abstract: The present invention relates to a method of preparing modified polypeptides, by linking a target polypeptide to a carrier molecule that is designed to bear one or more water-soluble polymer molecules, via protein trans-splicing. The polymer molecules can be attached to the carrier molecule either before or after ligation to the target polypeptide. Novel protein trans-splicing elements (known as “split inteins”) and trans-splicing partners are also provided.