Substrate Specificity of Ketosynthase Domains Part II Amino Acid-Containing Acyl Chains

Substrate Specificity of Ketosynthase Domains Part II Amino Acid-Containing Acyl Chains 

Substrate analogues without an amine or amide nitrogen substituted on the 2-position were not accepted by KSl at the standard assay concentration of 0.5 mM. Moreover, removal of Asn-206 from the active site of KSl by site-directed mutagenesis reduced kcat/Km by a factor of 2. This residue is conserved in most known 2-amidoacetyl-accepting KS domains from tran -AT PKSs and we postulate an important interaction between Asn-206 and the amide nitrogen of the substrate. 

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