Abstract: A method of designing or modifying protein structure at the protein or genetic level to produce specified amino-termini in vivo are described. The method can be used to alter the metabolic stability and other properties of the protein or, alternatively, to artificially generate authentic amino-termini in proteins produced through artificial means. The method is based upon the introduction of the use of artificial ubiquitin-protein fusions, and the discovery that the in vivo half-life of a protein is a function of the amino-terminal amino acid of the protein.

Abstract: A sensitive and general method of post-separation detection and quantification of chemical compounds is described. The method involves separation of unlabeled compounds by chromatography, electrophoresis or other means and selective binding of the separated compounds to ligands containing highly neutron-activatable elements, followed by neutron irradiation. The neutron-activatable elements are converted to their radiation-emitting isotopes by neutron absorption, and detection is done by autoradiography, fluorography or other means of radiation detection. The theoretical sensitivity of the method is in the attomole (10.sup.-18 mole) range.