Beaven G, Bowyer A, Erskine P, Wood S P, McCoy A, Coates L, Keegan R, Lebedev A, Hopper D J, Kaderbhai M A, Cooper J B
School of Biological Sciences, University of Southampton, Southampton, England.
Laboratory of Protein Crystallography, Centre for Amyloidosis and Acute Phase Proteins, UCL Division of Medicine (Royal Free Campus), Rowland Hill Street, London NW3 2PF, England.
Acta Crystallogr F Struct Biol Commun. 2014 Jun;70(Pt 6):823-6. doi: 10.1107/S2053230X14009649. Epub 2014 May 25.
The enzyme 2,4'-dihydroxyacetophenone dioxygenase (or DAD) catalyses the conversion of 2,4'-dihydroxyacetophenone to 4-hydroxybenzoic acid and formic acid with the incorporation of molecular oxygen. Whilst the vast majority of dioxygenases cleave within the aromatic ring of the substrate, DAD is very unusual in that it is involved in C-C bond cleavage in a substituent of the aromatic ring. There is evidence that the enzyme is a homotetramer of 20.3 kDa subunits each containing nonhaem iron and its sequence suggests that it belongs to the cupin family of dioxygenases. By the use of limited chymotrypsinolysis, the DAD enzyme from Alcaligenes sp. 4HAP has been crystallized in a form that diffracts synchrotron radiation to a resolution of 2.2 Å.
2,4'-二羟基苯乙酮双加氧酶（或DAD）催化2,4'-二羟基苯乙酮转化为4-羟基苯甲酸和甲酸，并结合分子氧。虽然绝大多数双加氧酶在底物的芳环内裂解，但DAD非常特殊，因为它参与芳环取代基中的碳-碳键裂解。有证据表明该酶是由20.3 kDa亚基组成的同四聚体，每个亚基都含有非血红素铁，其序列表明它属于双加氧酶的铜蛋白家族。通过有限的胰凝乳蛋白酶水解，来自产碱菌属4HAP的DAD酶已结晶成一种形式，该形式能将同步辐射衍射到2.2 Å的分辨率。
