CeuE. The resulting ArM slowly reduces salsolidine precursor (TON 400, 24 h) with
an e.r. of 67.7/32.3. CeuE mutant H227A increases TON (400, 2 h) but at the
expense of a substantially lowered e.r. (51.7/48.4) [134] (Scheme 23).
NADH and NAD(P)H play important roles as cofactors in numerous biocatalysed
processes [135]. In 2012, the groups of Sadler [136] and Fukuzumi [137] independently showed that half-sandwich iridium complexes can utilise NADH as a hydride
donor to generate an iridium-hydride complex. The hydrido complex is able to
transfer the hydride moiety to organic substrates. Regeneration of the iridiumN
Me
NH
Me
*
Cl
Ir
Cl
HN
NH
S
O
H
H
N
H
O
N
N
OH
HO
Iridium cofactor =
Host protein : Sav K121R
NAD(P)H
- NAD(P)
+
Scheme 21 Transfer hydrogenation employing NAD(P)H as a hydrogen source
N
NH
Cl
Ir
R
N
N
HCOONa
MOPS-buffer
ZnSO 4
pH 7.5
X
Y
X
Y
S
S
O
O
NH 2
O
O
X
Y
OMe OMe
OMe H
H
OMe
H
H
Anchor
Iridium diamine complex
Host protein:
hCAII WT
hCAII mutations (Rosetta design)
ArM
R= Me, nPr
Scheme 22 TH of isoquinolines mediated by ArMs. The Ir-cofactors are shown at the top, and the
host proteins employed are hCAII WT or mutants computationally designed
98
M. Pilar Lamata et al.