A scheme of the binding site is shown in Figure 3, with the amino acids Arg 47 and
Tyr 51 (which are responsible for the substrate fixation) and Phe 87 (which influences
the regioselectivity of the fatty acid hydroxylation) each being highlighted. The
substrate profile of P450 BM-3 is summarized in Table 2.
18.4 Fatty Acid-hydroxylating P450s Monooxygenases 401
Table 2.Substrate profile of P450 BM-3 wild-type and mutants.
Substrates Fatty acid
chain-length
P450 Km Kcat/Km References
[lM] [*10^5 M^1 *s^1 ]
Saturated FA WT 136, 7, 1.4 1.9, 82, 600 Oliver et al.,
1997a
C 12 ,C 14 ,C 16 R47E 2000, 18, 4 0.15, 3.9, 30 Oliver et al.,
1997a
C 12 F87A 167 1.5 Oliver et al.,
1997b
Polyunsaturated FA WT n.m. n.m. Capdevila et al.,
1996
C20:3,C20:4,C20:5 F87V n.m. n.m. Graham-Loren-
ce, 1997
x-Oxo-FA C 12 ,C 14 ,C 16 ,C 18 WT n.m. n.m. Davis et al., 1996
p-Nitrophenoxy-FA WT n.m. n.m. Schwaneberg et
al., 1999a
C 8 ,C 10 ,C 11 ,
C 12 ,C 15
F87A n.m. n.m. Schwaneberg et
al., 1999a
Trialkylmethylammo-
nium
WT 782, 87, 5 200, 25, 2 Oliver et al.,
1997a
C 12 ,C 14 ,C 16 R47E 95, 23, 9 23, 6.6, 0.22 Oliver et al.,
1997a
FA, fatty acids; n.m., not measured
Figure 3. Model of the heme-domain of P450 BM-3 with boundp-nitrophenoxy dodecanoic acid (12-
pNCA). Amino acids involved in substrate binding (Arg 47 ,Tyr 51 ) and regioselectivity (Phe 87 ) are high-
lighted.