Buffers for electrophoresis and use thereof

Abstract

Various embodiments provide, for example, buffer compositions and/or sieving formulations useful in connection with electrophoresis instruments, such as capillary electrophoresis (CE) devices. In various embodiments, a buffer composition can include Bis-Tris, TAPS and/or TAPSO, and, optionally, a chelating agent, such as EDTA. Methods of separating samples containing bio-molecules, such as DNA or RNA, are also described.

1 . A method for increasing an amount of DNA denaturation that occurs during electrophoresis of nucleic acids without significant loss of DNA resolution or run speed, said method comprising: 
 introducing a buffer to a gel, wherein said buffer comprises Bis-Tris, TAPS, and a metal-chelating agent, wherein said buffer lacks urea;    applying a sample including nucleic acids to be analyzed on said gel; and    applying an electromotive potential across the gel, whereby there is less loss of DNA resolution or run speed than if urea had been included in the buffer instead of the combination of Bis-Tris and TAPS.    
     
     
         2 . The method of  claim 2 , wherein the gel is supported in a channel defined by a capillary tube.  
     
     
         3 . The method of  claim 2 , wherein a pH of the buffer is at least 7.  
     
     
         4 . The method of  claim 2 , wherein a pH of the buffer is no less than 7.5.  
     
     
         5 . A method for facilitating an amount of DNA denaturation at a given temperature during electrophoresis, said method comprising: 
 introducing a buffer to a gel, wherein said buffer comprises Bis-Tris and TAPS;    applying a sample including nucleic acids to be analyzed on said gel;    applying a temperature of at least 50° C. to the gel; and    applying an electromotive potential across the gel, whereby an amount of denaturation that occurs at 50° C. in the buffer is greater than an amount of denaturation of the nucleic acids in a buffer having Tris but excluding Bis-Tris at a temperature of at least 60° C.    
     
     
         6 . The method of  claim 5 , wherein the amount of denaturation that occurs at 50° C. in the buffer is greater than an amount of denaturation of the nucleic acids in a buffer having Tris but excluding Bis-Tris at a temperature of 70° C.  
     
     
         7 . The method of  claim 5 , wherein a pH of the buffer is no less than 7.5.  
     
     
         8 . A method for increasing an amount of DNA denaturation that occurs during electrophoresis comprising: 
 identifying a sample as having nucleic acids that could benefit from an increased amount of denaturation during electrophoresis;    introducing a buffer to a gel, wherein said buffer comprises at least Bis-Tris and TAPS;    applying the sample including nucleic acids to be analyzed on said gel; and    applying an electromotive potential across the gel.    
     
     
         9 . The method of  claim 8 , wherein the electrophoresis is capillary electrophoresis.  
     
     
         10 . The method of  claim 8 , wherein a pH of the buffer is no less than 7.5.  
     
     
         11 . The method of  claim 8 , wherein, despite the increase in denaturation, said nucleic acid runs without a significant loss of DNA resolution or run speed when the electromotive potential is applied across the gel because urea is not present in the buffer.  
     
     
         12 . A method for decreasing compression that occurs during electrophoresis of nucleic acids comprising: 
 identifying a sample as having nucleic acids that could benefit from a decreased amount of compression during electrophoresis;    introducing a buffer to a gel, wherein said buffer comprises at least Bis-Tris and TAPS;    applying the sample including nucleic acids to be analyzed on said gel; and    applying an electromotive potential across the gel.    
     
     
         13 . The method of  claim 12 , wherein the buffer further comprises an organic solvent.  
     
     
         14 . The method of  claim 12 , wherein the buffer further comprises formamide, urea, or both formamide and urea.  
     
     
         15 . The method of  claim 12 , wherein a pH of the buffer is no less than 7.5.  
     
     
         16 . A method for the electrophoresis of nucleic acids, comprising: 
 introducing a buffer to a gel, wherein said buffer comprises Bis-Tris, TAPS, and a metal-chelating agent;    applying a sample including nucleic acids to be analyzed on said gel; and    applying an electromotive potential difference across said gel, whereby the sample is resolved, wherein the gel is supported in a channel defined by a capillary tube comprising a cold zone, wherein an amount of compression that occurs from resolving the sample by electrophoresis through the capillary tube is less than an amount that occurs in a Tris buffer that lacks Bis-Tris.    
     
     
         17 . A method for gel electrophoresis, said method comprising: 
 introducing a buffer to a gel in order to increase an amount of DNA denaturation or decrease an amount of compression that would occur in nucleic acids to be analyzed in the gel, said buffer comprising Bis-Tris, TAPS, and a metal-chelating agent;    applying a sample including nucleic acids to be analyzed on said gel; and    applying an electromotive potential across the gel.    
     
     
         18 . A composition for electrophoresis of nucleic acids, the composition comprising: 
 (a) an organic polymer,    (b) Bis-Tris,    (c) one or more members of the group TAPS, TAPSO, and Asparagine; and    (d) a metal-chelating agent,    wherein the organic polymer comprises a sieving component comprising a non-crosslinked acrylamide polymer, and a surface interaction component comprising one or more non-crosslinked polymers selected from the group consisting of N,N-disubstituted polyacrylamide, N-substituted polyacrylamide, N-monosubstituted polyacrylamides, polymethacrylamide, polyvinylpyrrolidone, and poly(N,N-dimethylacrylamide), and wherein the resolving-gel composition has a pH of greater than 7.    
     
     
         19 . The composition of  claim 18 , comprising TAPS, and wherein the gel is contained within an electrophoretic capillary.  
     
     
         20 . The composition of  claim 18 , having a pH no less than 7.5.  
     
     
         21 . The composition of  claim 18 , wherein the non-crosslinked acrylamide polymer is selected from the group consisting of: linear polyacrylamide, branched acrylamide polymers, and star-shaped acrylamide polymers.