Effect of Salt on Dimerisation and Acylation

In contrast to most KS domains, BaeJ KSl was soluble in 5 mM NaCl/ NH4OAC, allowing the oligomeric state of the KS to be monitored using a combination of analytical gel filtration and native MS. Analytical gel filtration revealed exclusively monomer at 500 mM NaCl, however at 5 mM NaCl, the dimeric KS 1 was observed at a lower elution volume. The dimer peak appeared to leech into the monomer peak suggesting the existence of an equilibrium between the two species (Fig. 4.12). 

With the ability to control the oligomeric state of the KS, it seemed logical to test the capacity of the native SNAC 27 to acylate KSl at different salt concentrations. Under the standard assay conditions used previously, KSl in either 5 mM or 

The shift in retention time suggests that dimeric KSl is formed under low salt conditions 

4 Substrate Specificity of Ketosynthase Domains. .. Dimeric Monomeric 

Red circles indicate monomeric KS 1, and blue diamonds represent dimeric KSl 

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