UNIT 3.14 DNA Ligases

  1. Stanley Tabor

Published Online: 1 MAY 2001

DOI: 10.1002/0471142727.mb0314s08

Current Protocols in Molecular Biology

Current Protocols in Molecular Biology

How to Cite

Tabor, S. 2001. DNA Ligases. Current Protocols in Molecular Biology. 8:III:3.14:3.14.1–3.14.4.

Author Information

  1. Harvard Medical School, Boston, Massachusetts

Publication History

  1. Published Online: 1 MAY 2001
  2. Published Print: OCT 1989

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DNA ligases catalyze the formation of phosphodiester bonds between juxtaposed 5' phosphate and a 3'-hydroxyl terminus in duplex DNA. This activity can repair single-stranded nicks in duplex DNA and join duplex DNA restriction fragments having either blunt ends or homologous cohesive ends. Two ligases are used for nucleic acid research and their reaction conditions and applications are described in this unit: E. coli ligase and T4 ligase. These enzymes differ in two important properties. One is the source of energy: T4 ligase uses ATP, while E. coli ligase uses NAD. Another important difference is their ability to ligate blunt ends; under normal reaction conditions, only T4 DNA ligase will ligate blunt ends.