Evaluating proteins

Abstract

The disclosure features methods that include: providing a substrate that includes (i) a nucleic acid (e.g., DNA or RNA) encoding a hybrid amino acid sequence including a test amino acid sequence and an affinity tag, and (ii) a binding agent that recognizes the affinity tag; contacting the substrate with a translation effector to thereby translate the hybrid amino acid sequence; maintaining the substrate under conditions permissive for the hybrid amino acid sequence to bind the binding agent; and removing the nucleic acid from the substrate. In one embodiment, the substrate includes a plurality of positionally-distinguishable addresses, for example, each includes a different nucleic acid. The addresses can be located a regularly or irregularly spaced locations.

1 - 8 . (canceled) 
     
     
         9 . A substrate that comprises a surface that includes a surface modification with a group that selectively binds to nucleic acid, and coding nucleic acids distributed at various locations on the surface. 
     
     
         10 . The substrate of  claim 9 , wherein the surface is substantially planar. 
     
     
         11 . The substrate of  claim 9 , wherein the surface further comprises a binding agent that recognizes a tag and the coding nucleic acids encode polypeptides that include the tag. 
     
     
         12 . The substrate of  claim 9 , wherein the surface group is NH 2 —[CH2] n —NH 3   +  and n is between 2 and 5. 
     
     
         13 . The substrate of  claim 9 , wherein the surface group is mono-amino-N-aminoethyl (MANAE). 
     
     
         14 - 20 . (canceled) 
     
     
         21 . A substrate comprising:
 (a) a metallic surface; and   (b) an array of protein aggregates disposed on the surface.   
     
     
         22 . The substrate of  claim 21 , wherein the surface is gold. 
     
     
         23 . The substrate of  claim 21 , wherein the surface is substantially planar. 
     
     
         24 . The substrate of  claim 21 , wherein the aggregates are formed by crosslinking soluble proteins prior to disposing the proteins on the surface. 
     
     
         25 - 30 . (canceled)