Gene Isolation, Detection, and Verification

For spectrometry, relatively large amounts of DNA are required ( 0.25 pg mL 1). The purity of nucleic acids can be determined by the ratio of extinction at 260 to that at 280 nm. Pure DNA has a ratio of 1.8, pure RNA one of 2.0. The DNA concentration can be determined using the approximate values in Table 4.2. 

the gene sequence is fully known from databases (see Chapter 14 for how to get this information), or 

only part of the sequence is known, such as the N-terminal sequence, if the full sequence of the protein or DNA has not been submitted yet. 

---