Hydrophobicity of residue 108 specifically affects the affinity of human β-carotene 15,15′-monooxygenase for substrates with two ionone rings
2010
Kim, Yeong-Su | Park, Chang-Su | Oh, Deok-Kun
The Lys residue at position 108 of human β-carotene 15,15′-monooxygenase is located on the outside surface of the active tunnel of the enzyme. Hydrophobic mutations (K108F and K108L) at this position substantially decreased the affinity of the enzyme for substrates with ionone rings at both ends, such as α-carotene, β-carotene, and β-cryptoxanthine. In contrast, these mutations had little effect on the affinity of the enzyme for substrates with one ionone ring and one open-chain end, such as β-apo-4′-carotenal and β-apo-8′-carotenal. The residue 108 may be related to the indirect interaction with the second ionone ring of the substrates with two ionone rings.
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