title: Different substrate specificities of the two DNA ligases of mammalian cells.
abstract: Mammalian cells contain the DNA ligases I and II. These enzymes show different molecular weights and heat labilities, and antibodies against ligase I do not inhibit ligase II. Here, the nonidentical substrate specificities of the enzymes are described. Under standard reaction conditions DNA ligase I, but not ligase II, catalyzes blunt-end joining of DNA, while ligase II is the only activity that joins oligo(dT) molecules hydrogen-bonded to poly(rA). These differences facilitate the distinction between the two enzymes and should permit further analysis of their functions.
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000378:metabolism; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism*; D006860:Hydrogen Bonding; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D011061:Poly A / Q000378:metabolism; D011118:Polynucleotide Ligases / Q000378:metabolism*; D013379:Substrate Specificity; D013604:T-Phages / Q000201:enzymology; D013950:Thymus Gland / Q000201:enzymology
chemical_list: D009838:Oligodeoxyribonucleotides; C027903:oligo (dT); D011061:Poly A; D004247:DNA; D011088:DNA Ligases; D011118:Polynucleotide Ligases; D000072481:DNA Ligase ATP