[lily_m]

Hello all, can someone please help me with this question. I conducted a DNA ligase experiment with 1 μl of digested pUC18 DNA with 1 μl of DNA ligase enzyme and ran the ligated sample next to a control with agarose gel electrophoresis. My problem is that the ligated sample has appeared to decrease in band size in comparison to the control. I expected an increased due to the joining of DNA fragments. Can anybody please tell me why this is so??

[Yggdrasil]

Are you converting a linear DNA into a circular DNA?  Circular DNAs tend to run faster than linear DNAs on agarose gels and could account for the higher mobility of your ligated sample.