Endonuclease standard

In many localities, newborn screening has become standard for this disorder, which in the general population has an approximate incidence of 1/250,000 live births. Carrier detection is possible, either by measurement of enzymatic activity in cultured fibroblasts or by study of restriction endonuclease fragments of DNA. Antenatal testing is also available. 

Students may characterize A phage or adenovirus 2 DNA. Both are standard substrates for assays of restriction endonucleases. 

After extraction by either procedure, the puri-fled DNA concentration is usually about 1 mg/ml and can be quantified either by using a spectrophotometer monitoring the solution absorbance at 260 and 280 nm or by gel electrophoresis against known concentration standards. The purified DNA is free of other cellular components such as free nucleases which can interfere with other DNA processing techniques required in biological research such as restriction endonuclease cutting, PCR amplification, or gel electrophoresis. 

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