Polypeptide multilayer films and methods

Abstract

Polypeptide multilayer films comprising a hydrophobic designed polypeptide, methods of making the polypeptide multilayer films, and methods of designing the hydrophobic polypeptide are disclosed.

1 . A multilayer film comprising: 
 a plurality of layers of polyelectrolytes, the layers comprising alternating oppositely charged polyelectrolytes,    wherein a first layer comprises a hydrophobic designed polypeptide,    wherein the hydrophobic designed polypeptide comprises 
 one or more hydrophobic amino acid sequence motifs,  
 a length of greater than or equal to 15 amino acid residues, and  
 a magnitude of a net charge per residue of less than 0.4 at pH 7, 
 the one or more hydrophobic amino acid sequence motifs comprising length n, at least one nonpolar amino acid residue, and a magnitude of a net charge per residue less than 0.4 but greater than 1/n, wherein n is 5 to 15,  
 
   and wherein a second layer comprises a second layer polyelectrolyte having a charge opposite that of the hydrophobic designed polypeptide.    
     
     
         2 . The multilayer film of  claim 1 , wherein the magnitude of the net charge per residue of the hydrophobic designed polypeptide is less than 0.25 at pH 7.  
     
     
         3 . The multilayer film of  claim 1 , wherein the second layer polyelectrolyte comprises a hydrophilic designed polypeptide comprising 
 one or more hydrophilic amino acid sequence motifs, 
 wherein the one or more hydrophilic amino acid sequence motifs consists of 5 to 15 amino acids and has a magnitude of a net charge per residue of greater than 0.4,  
   wherein the hydrophilic designed polypeptide is at least 15 amino acids long, and has a magnitude of a net charge per residue of greater than 0.4.    
     
     
         4 . The multilayer film of  claim 1 , wherein the multilayer film is formed on a substrate.  
     
     
         5 . The multilayer film of  claim 4 , wherein the substrate is a nitrocellulose membrane, a silicon wafer, silicone, a surface treated with an alkylsilane, or an organic polymer lattice.  
     
     
         6 . The multilayer film of  claim 1 , comprising at least 4 pairs of alternately charged layers.  
     
     
         7 . The multilayer film of  claim 1 , having a thickness of 1 nm to 100 nm.  
     
     
         8 - 17 . (canceled)  
     
     
         18 . A method for identifying a hydrophobic amino acid sequence motif, comprising 
 locating a starter amino acid in a first amino acid sequence;    examining a second amino acid sequence comprising the starter amino acid and a following n−1 amino acids in the first amino acid sequence for occurrences of positive and negative charges at pH 7; and    identifying the second amino acid sequence as a hydrophobic amino acid sequence motif if a magnitude of a net charge per residue of the second amino acid sequence is at least 1/n and less than 0.4; or    discarding the second amino acid sequence if the magnitude of the net charge of the second amino acid sequence is less than 1/n or greater than or equal to 0.4,    wherein n is 5 to 15.    
     
     
         19 . A method of designing a hydrophobic designed polypeptide, comprising 
 identifying a hydrophobic amino acid sequence motif comprising n amino acids, wherein a magnitude of a net charge per residue of the hydrophobic amino acid sequence is at least 1/n and less than 0.4, and wherein n is 5 to 15; and    covalently joining two or more hydrophobic amino acid sequence motifs;    wherein the two or more hydrophobic amino acid sequence motifs are the same or different.    
     
     
         20 . The multilayer film of  claim 1 , wherein the hydrophobic designed polypeptide comprises two or more hydrophobic amino sequence motifs joined by 1-4 glycine or proline residues.  
     
     
         21 . The multilayer film of  claim 1 , wherein the hydrophobic amino acid sequence motif has a solubility at 25° C. of less than 50 μg/mL in water.  
     
     
         22 . The multilayer film of  claim 1 , wherein the hydrophobic designed polypeptide has a summed α-helix propensity of less than 7.5 and a summed β sheet propensity of less than 8.  
     
     
         23 . The multilayer film of  claim 1 , wherein the hydrophobic amino acid sequence motif is designed de novo.