Overview of E. coli single stranded binding protein SSB and its cooperativity.

E. coli single stranded binding protein (Eco SSB) is encoded by ssb gene which consists of 534 bp in coding region. Product of ssb gene contains 177 amino acids with a molecular weight of 18,9 kDa. In solution, Eco SSB forms a tetramer as the active form (sometimes be viewed as a “dimer of dimers”). SSB is known to tightly bind single stranded DNA (ssDNA) with very high affinity and protects that ssDNA from nuclease, reannealing or secondary formation …  or keeps ssDNA intermediates, therefore involved Continue Reading →

What is Klenow fragment?

E. coli Polymerase I is a product of polA gene that consists of 5′-3′ polymerase activity and both 3′-5′ and 5′-3′ exonuclease activity. In vivo, Pol I takes part in DNA synthesis and DNA repair. The 5′-3′ exonuclease activity of Pol I makes it unsuitable for many applications in vitro. However, it is found that a protease known as subtilisin, can cleave Pol I into a small fragment, which contains the 5′ -> 3′ exonuclease activity, and a large fragment that consists of both 5′-3′ polymerase activity and 3′-5′ exonuclease activity called Klenow Continue Reading →