How and Why Are Some Riboflavin Coenzymes Covalently Attached to Proteins?
1992 年 38 巻 Special 号 p. 40-45
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1992 年 38 巻 Special 号 p. 40-45
Covalent flavinylation as elucidated by the formation of the histidyl(N3)-8α-flavin bond in 6-hydroxy-D-nicotine oxidase of A. oxidans proceeds by an non-enzymatic mechanism. Incubation of the apoenzyme, FAD and a three-carbon phosphate ester at neutral pH leads to the formation of an enzymatically fully active holoenzyme. The role of His71 in this process was illustarated by site-directed mutagenesis. Nevertheless, the question whether covalent attachment of the cofactor in a holoenzyme has prevailed throughout the evolutionary screening process because of biological significance or whether it is a chance event of neutral selective value [5] is still open.
