title: AP endonuclease activity in humans: development of a simple assay and analysis of ten normal individuals.
abstract: The human AP endonuclease (APE) activity counteracts the mutagenic and cytotoxic effects of the frequent genomic lesions abasic (AP) sites. In order to investigate the interindividual variability of APE levels, a simple and quantitative assay was developed. Crude lymphocyte extracts were incubated with a depurinated or a control supercoiled plasmid substrate, and the accumulation of nicked circular plasmid forms was monitored by agarose gel electrophoresis. The detected incision activity was AP sites-dependent and EDTA-sensitive. The unit of enzymatic activity was defined as that amount able to incise 1 ng of plasmid DNA carrying 1 AP site/plasmid at 30 degrees C in 10 min. The assay was used to measure the APE activity in 10 healthy individuals ages 25-48 years. Values ranged from 0.38 to 0.94 units/ng protein, with a mean value of 0.62. The use of the assay for screening of people with DNA base excision repair (BER) defects is proposed.
authors.affiliation: DNA Repair Unit, CSTA Laboratory, Istituto Nazionale Ricerca Cancro, Genova, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Redaelli
authors.forename: R
authors.initials: R
authors.lastname: Magrassi
authors.forename: S
authors.initials: S
authors.lastname: Bonassi
authors.forename: A
authors.initials: A
authors.lastname: Abbondandolo
authors.forename: G
authors.initials: G
authors.lastname: Frosina
mesh_terms: D000328:Adult; D019757:Carbon-Oxygen Lyases / Q000097:blood* / Q000378:metabolism; D015197:Carcinogenicity Tests / Q000379:methods*; D004260:DNA Repair / Q000187:drug effects; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D003720:Densitometry; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004587:Electrophoresis, Agar Gel; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D010957:Plasmids / Q000378:metabolism
chemical_list: D043223:Deoxyribonuclease IV (Phage T4-Induced); D019757:Carbon-Oxygen Lyases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase