Task: Class Definition Understanding (ontology: Sciences/Biology)

Which of the following definitions best describes 'DNA-7-methyladenine glycosylase activity'?

A. Catalysis of the reaction: DNA containing 7-methyladenine + H2O = DNA with abasic site + 7-methyladenine. This reaction is the hydrolysis of DNA by cleavage of the N-C1' glycosidic bond between the damaged DNA 7-methyladenine and the deoxyribose sugar to remove the 7-methyladenine, leaving an abasic site.
B. Catalysis of the reaction: DNA with 1-N6-ethenoadenine + H2O = DNA with abasic site + 1-N6-ethenoadenine. This reaction is the removal of 1,N6-ethenoadenine by cleaving the N-C1' glycosidic bond between the target damaged DNA base and the deoxyribose sugar.
C. Catalysis of the reaction: DNA containing 7-methylguanine + H2O = DNA with abasic site + 7-methylguanine. This reaction is the hydrolysis of DNA by cleavage of the N-C1' glycosidic bond between the damaged DNA 7-methylguanine and the deoxyribose sugar to remove the 7-methylguanine, leaving an abasic site.
D. Catalysis of the reaction: DNA containing 3-methylbase + H2O = DNA with abasic site + 3-methylbase. This reaction is the hydrolysis of DNA by cleavage of the N-C1' glycosidic bond between the damaged DNA 3-methylpurine or 3-methylpyrimidine base and the deoxyribose sugar to remove the methylated base, leaving an apurinic or apyrimidinic site.

Answer: Catalysis of the reaction: DNA containing 7-methyladenine + H2O = DNA with abasic site + 7-methyladenine. This reaction is the hydrolysis of DNA by cleavage of the N-C1' glycosidic bond between the damaged DNA 7-methyladenine and the deoxyribose sugar to remove the 7-methyladenine, leaving an abasic site.