The Presence of 3'–5' Exonuclease Activity in Rat Brain Neurons and Its Role in Template-Driven Extension of 3'-Mismatched Primers by DNA-Polymerase β in Aging Neurons.

Autor: T. Hari Krishna, Anjana Hemkal, Kalluri Subba Rao
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Zdroj: Neurochemical Research; Apr2004, Vol. 29 Issue 4, p761-770, 10p
Abstrakt: A three-step reaction strategy has been developed to examine the mechanism of extension of a mismatched primer in an oligoduplex substrate by rat neuronal extracts and DNA polymerase β. The results revealed that in the case of duplexes with a mismatch at 3'-end of primer, significant extension by DNA polymerase β has taken place only after the removal of the mismatched base, thus indicating the presence of a proof reading 3'–5' exonuclease activity in neuronal extracts of all ages. A closer examination of the neuronal exonuclease activity revealed that bases are excised from the 3' end in a sequential and nonspecific manner, although initial excision of a mismatched base was slightly faster. Further, the excision efficiency is seen to decrease with the age of the animal but apparently does not go below a critical level so as to become a rate-limiting factor for the DNA-repair activity. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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