Enzymatic excision of 3-methyladenine and 7-methylguanine by a rat liver nuclear fraction

Journal Article · Thu Jan 01 04:00:00 EST 1981 · Biochemistry; (United States)

OSTI ID:6029240

Cathcart, R; Goldthwait, D A

A 3-methyladenine-DNA N-glycosylase was identified in both nuclear and cytoplasmic extracts of rat liver. The enzyme was purified from nuclei due to a lower level of nonspecific nucleases. The enzyme was purified 100-fold by using DNA-cellulose and phosphocellulose chromatography. Several methods of assay were developed and are discussed. The molecular weight of the glycosylase was 24000. It exhibited a preference for double-stranded alkylated DNA. The apparent K/sub m/ for 3-methyladenine residues was 2.6 nM. The enzyme was shown to be a glycosylase by the stoichiometric release of 3-methyladenine and the appearance of alkali-sensitive sites. There was no endonucleolytic activity on double-stranded DNA, depurinated DNA, UV-treated DNA, or ..gamma..-irradiated DNA. The relative rate of release of 3-methyladenine and 7-methylguanine was the same for both the DNA-cellulose and phosphocellulose fractions, and both activities were inactivated by heat to the same extent. Whether one or two enzymes are involved is not known. The preparation does not release 3-methylguanine or 1-methyladenine.

• Research Organization: Case Western Reserve Univ., Cleveland, OH
• DOE Contract Number: AC02-76EV02725
• OSTI ID: 6029240
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 20:2; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ADENINES
ALKYLATION
AMINES
ANIMALS
ANTIMETABOLITES
AROMATICS
AZAARENES
BIOCHEMICAL REACTION KINETICS
BODY
CHEMICAL REACTIONS
CHROMATOGRAPHY
DIGESTIVE SYSTEM
DNA
DRUGS
ENZYME ACTIVITY
ENZYMES
GLANDS
GLYCOSYL HYDROLASES
GUANINE
HETEROCYCLIC COMPOUNDS
HYDROLASES
HYDROXY COMPOUNDS
KINETICS
LABELLED COMPOUNDS
LIQUID COLUMN CHROMATOGRAPHY
LIVER
MAMMALS
METHYLATION
MOLECULAR WEIGHT
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PURINES
RATS
REACTION KINETICS
RODENTS
SEPARATION PROCESSES
STRAND BREAKS
TRITIUM COMPOUNDS
VERTEBRATES