NEGATIVE STAINING OF PROTEINS IN POLYACRYLAMIDE GELS WITH METHYL TRICHLOROACETATE

This paper describes a new, sensitive (in the nanogram range), and rap id (two-step) technique for the negative staining of proteins in polya crylamide gels in the presence or absence of sodium dodecyl sulfate. A fter separation, gels are incubated with 8% methyl trichloroacetate es ter in 38% isopropanol and then washed in water to produce a negative image of colorless proteins against an opaque background. The techniqu e allows unmodified proteins to be recovered for biological studies or transblot for amino acid sequence. Finally, owing to the reversibilit y of the process, gels can be restained after rapid visualization. For these reasons, negative staining with methyl trichloroacetate should become the method of choice for rapid and sensitive staining of protei ns prior to further processing, including stable staining with silver ions. (C) 1996 Academic Press, Inc.