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The variant ‘his‐box’ of the C18‐Δ9‐PUFA‐specific elongase IgASE1 from Isochrysis galbana is essential for optimum enzyme activity
Author(s) -
Qi Baoxiu,
Fraser Thomas C.M.,
Bleakley Claire L.,
Shaw Elisabeth M.,
Stobart A.Keith,
Lazarus Colin M.
Publication year - 2003
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(03)00676-8
Subject(s) - isochrysis galbana , biochemistry , histidine , polyunsaturated fatty acid , glutamine , amino acid , enzyme , biology , chemistry , fatty acid , botany , algae
IgASE1, a C18‐Δ9‐polyunsaturated fatty acid‐specific fatty acid elongase component from Isochrysis galbana , contains a variant histidine box (his‐box) with glutamine replacing the first histidine of the conserved histidine‐rich motif present in all other known equivalent proteins. The importance of glutamine and other variant amino acid residues in the his‐box of IgASE1 was determined by site‐directed mutagenesis. Results showed that all the variation in amino acid sequence between this motif in IgASE1 and the consensus sequences of other elongase components was required for optimum enzyme activity. The substrate specificity was shown to be unaffected by these changes suggesting that components of the his‐box are not directly responsible for substrate specificity.