Peptide library formats and methods relating thereto

A method for detecting the interaction between a peptide and a target comprising:

• (I) attaching linkers to a plurality of beads;
• (ii) attaching a plurality of peptides to the beads via covalent bonds to the linkers, each bead having associated therewith multiple copies of only a single peptide;
• (iii) cleaving at least some of the covalent bonds so that at least a substantial portion of the multiple copies are associated with each bead via noncovalent bonds;
• (iv) placing the target in a container;
• (v) overlaying the target with a substrate that is free of the target, the substrate constructed and arranged to permit only localized diffusion of the peptides therein;
• (vi) applying the plurality of beads to the substrate in a manner such that the beads are separated from the target by the substrate and such that the beads are substantially spaced-apart from one another and are immobilized on the substrate;
• (vii) allowing the substantial portion of the multiple copies to diffuse through the substrate and interact with the target, thereby resulting in a localized signal at the target;
• (vii) detecting the localized signal;
• (ix) associating the localized signal with one or a limited number of the plurality of beads applied to the substrate;
• (x) isolating a bead in the vicinity of the localized signal;
• (xi) sequencing the peptide at the bead in the vicinity of the localized signal.

A method for determining the relative potency of an interaction between a peptide and a target, the method comprising:

• (I) placing the target in a container;
• (ii) overlaying the target with a substrate that is free of the target, the substrate constructed and arranged to permit only localized diffusion of the peptides therein;
• (iii) applying a plurality of beads to the substrate in a manner such that the beads are separated from the target by the substrate and such that the beads are substantially spaced-apart from one another and are immobilized on the substrate, each bead having associated therewith copies of only a single peptide, wherein at least a substantial portion of the multiple copies is associated with each bead via non-covalent bonds;
• (iv) allowing the substantial portion of the multiple copies to diffuse through the substrate and interact with the target, thereby resulting in a localized signal associated with the target;
• (v) associating the localized signal with one or a limited number of the plurality of beads applied to the substrate;
• (vi) measuring the localized signal at pre-selected time intervals;
• and
• (vii) determining the rate of change of the localized signal as a function of the time intervals, whereby the rate of change is proportional to the potency of the interaction between the peptide and the target.