Patent ID: 7488579

Claim:
A method of isolating DNA, RNA and protein simultaneously from biological samples comprises: a) extracting DNA, RNA and protein simultaneously from the biological samples with extracting solutions comprising pH from 9.5 to 10.5 extraction reagent, wherein the extraction reagent comprising phenol and a buffer with pH from 9.5 to 10.5; b) separating the solutions containing said DNA, RNA and protein from step a) into an upper aqueous phase, a lower organic phase and an inter-phase there between to recover a DNA and RNA mixture from the upper aqueous phase, wherein said DNA and RNA mixture is substantially protein-free, and said upper aqueous phase has pH about 9.5 to 10.5; c) separating the DNA and RNA mixture into separated DNA and RNA by selective precipitation and/or selective enzyme digestions; d) recovering the separated DNA and RNA for applications; e) extracting protein from the lower phase wherein said protein is substantially free of DNA and RNA; and f) Obtaining six classes of different specimens wherein said specimens are DNA and RNA mixture; substantially pure RNA without undergoing DNase treatment; substantially pure DNA without undergoing RNase treatment; substantially pure RNA obtained after DNase treatment; substantially pure DNA obtained after RNase treatment; and protein pool with full representing population of different proteins contained in said biological samples.