Protein & Nucleic Acid Isolation

Tissue homogenates or cell extracts are complex mixtures from which to purify macromolecules. Nucleic acids make crude homogenates viscous, and can bind—specifically or non-specifically—to proteins. Nucleic acids can be precipitated by alcohols, but any residual DNase or RNase can destroy the sample.

We offer a set of products for nonspecific digestion of either nucleic acids or proteins. They vary by cleavage specificity as well as by properties such as pH optimum, allowing the investigator to choose the digestive enzyme best suited to experimental needs. Desoxyribonuclease I from mammalian sources, for example, yields products with terminal 5’-phosphates, while DNase II gives terminal 3’-phosphates. Neither nuclease cleaves RNA. Benzonase from Serratia marcescens will cleave all nucleic acids, while another bacterial nuclease--P1 from Penicillium citrinum -- degrades single-stranded DNA and RNA, but not double stranded DNA. Ribonuclease A will hydrolyze any RNA contaminating protein samples or preparations of plasmid DNA. Many of these enzymes have additional uses in molecular biology. For example, DNase I “nicks” DNA to allow incorporation of labeled bases. RNase A is a tool in the RNase protection assay that measures the abundance of specific mRNA’s.

In this group we also list an agarase that can digest low melting point agarose, used for retrieving oligonucleotides from gels.