Patent ID: 7700523

Claim:
A method of selecting a zinc finger polypeptide, comprising producing a library of zinc finger proteins differing in sequence from one another in at least positions 2 and 6 of adjacent fingers by randomizing a zinc finger protein comprising a plurality of zinc fingers, each finger having positions −1 to 9 with position 1 representing the first amino acid of an alpha-helix, in at least positions 2 and 6 of adjacent fingers, wherein the randomizing at position two is effected with a group of amino acids consisting of D, A, R, Q, H, K, S, and N and the randomizing at position six is effected with a group of amino acids consisting of R, Q, V, A, E, K, N, and T and wherein the randomizing at positions −1, 1, 2, 3, 5, and 6 of the first finger and positions −1, 1, 2, and 3 of the second finger is effected with amino acids consisting of the groups shown below for the respective positions: Position Amino Acids: −1 R, Q, H, N, D, A, T 1 S, R, K, N 2 D, A, R, Q, H, K, S, N 3 H, N, S, T, V, A, D 5 I, T, K 6 R, Q, V, A, E, K, N, T contacting the library with a target nucleic acid; selecting a zinc finger polypeptide from the library that binds to the target.