초록 ▼

In order to obtain a novel binding protein against a chosen target, DNA molecules, each encoding a protein comprising one of a family of similar potential binding domains and a structural signal calling for the display of the protein on the outer surface of a chosen bacterial cell, bacterial spore o

In order to obtain a novel binding protein against a chosen target, DNA molecules, each encoding a protein comprising one of a family of similar potential binding domains and a structural signal calling for the display of the protein on the outer surface of a chosen bacterial cell, bacterial spore or phage (genetic package) are introduced into a genetic package. The protein is expressed and the potential binding domain is displayed on the outer surface of the package. The cells or viruses bearing the binding domains which recognize the target molecule are isolated and amplified. The successful binding domains are then characterized. One or more of these successful binding domains is used as a model for the design of a new family of potential binding domains, and the process is repeated until a novel binding domain having a desired affinity for the target molecule is obtained. In one embodiment, the first family of potential binding domains is related to bovine pancreatic trypsin inhibitor, the genetic package is M13 phage, and the protein includes the outer surface transport signal of the M13 gene III protein.

대표청구항 ▼

A method of obtaining a nucleic acid encoding a binding protein having a proteinaceous binding domain that binds a predetermined target material, said target being a substance other than an antibody with an exposed antigen-combining site, comprising: a) preparing a variegated population of amplifiab

A method of obtaining a nucleic acid encoding a binding protein having a proteinaceous binding domain that binds a predetermined target material, said target being a substance other than an antibody with an exposed antigen-combining site, comprising: a) preparing a variegated population of amplifiable genetic packages, said genetic packages being selected from the group consisting of cells, spores and viruses, each said genetic package being genetically alterable and having an outer surface including a genetically determined outer surface protein, each package including a first nucleic acid construct coding for a chimeric potential binding protein, each said chimeric protein comprising and each said construct comprising DNA encoding (i) a potential binding domain which is a mutant of a predetermined domain of a predetermined parental protein other than a single chain antibody, and (ii) an outer surface transport signal for obtaining the display of the potential binding domain on the outer surface of the genetic package, the expression of which construct results in the display of said chimeric potential binding protein and its potential binding domain on the outer surface of said genetic package: and wherein said variegated population of genetic packages collectively display a plurality of different potential binding domains, the differentiation among said plurality of different potential binding domains occurring through the at least partially random variation of one or more predetermined amino acid positions of said parental binding domain to randomly obtain at each said position an amino acid belonging to a predetermined set of two or more amino acids, the amino acids of said set occurring at said position in statistically predetermined expected proportions, said genetic packages being amplifiable in cell culture and separable on the basis of the potential binding domain displayed thereon, b) causing the expression of said chimeric potential binding proteins and the display of said potential binding domains on the outer surface of said packages; c) contacting said packages with the predetermined target material such that said potential binding domains and the target material may interact; d) separating packages displaying a potential binding domain that binds the target material from packages that do not so bind, and e) recovering at least one package displaying on its outer surface a chimeric binding protein comprising a successful binding domain (SBD) which bound said target, said package comprising nucleic acid encoding said successful binding domain, and amplifying said SBD-encoding nucleic acid in vivo or in vitro.