Biology Reference
In-Depth Information
The first group of 92 compounds inhibited the adenylyl cyclase reporter enzyme of
PDE5-GAF-CyaB1 and had no discernible effect on GAF-mediated allosteric regu-
lation. These compounds were equally active at saturating cGMP concentrations of
100 m M and at 10 m M cGMP and, thus, are not considered to be competitive with
cGMP. This group of chemicals may be of interest as inhibitors of adenylyl cyclase in
mammals because the cyanobacterial cyclase is a class III isoform as are all eukary-
otic isoforms. NYC92338 (shown in Fig. 4 ) is a representative for the first group of
compounds. In the absence of cGMP, it inhibited nearly as potent (logIC 50 ¼
5.7)
as in the presence of 10 or 100 m McGMP(logIC 50 ¼
-6.1) (Fig. 5a ).
The second group comprised 166 compounds that inhibited both cyclase activa-
tion via the GAF domain and the adenylyl cyclase reporter enzyme. Most of these
were equally effective in the retests with 10 and 100 m M cGMP and, thus, were not
competitive with respect to cGMP. The large number of compounds in this group
suggests that the site of action may be a purine-binding site in either subdomain of
PDE5-GAF-CyaB1. NYC292005 (shown in Fig. 4 ) is a representative for the
second group: In the absence of cGMP a partial inhibition of PDE5-CyaB1 was
observed (log IC 50 ¼
5.4), while in the presence of 10 m M or 100 cGMP the
inhibition was complete (logIC 50 ¼
5.6) (Fig. 5b ); thus, both the tandem GAF
domain and other parts of the chimeric protein are involved in inhibition.
The third group comprised seven compounds that inhibited PDE5-GAF-CyaB1 in
spite of activating the adenylyl cyclase reporter in PDE5-GAF-CyaB1. As the ade-
nylyl cyclase activity determines signal intensity, it is assumed that these compounds
inhibit GAF activation more potently than observed in this assay. NYC57569 (Fig. 4 )
is a representative for this group (Fig. 5d, e ). These chemicals could, in principle, be of
further interest as GAF inhibitors. However, due to undesirable chemical and physi-
cochemical properties, these compounds were excluded from further evaluation.
O
O
Br
Br
N +
O
N
O
N
O
B
F
NYC175273
NYC57569
NYC118277
N
O
OH
S
OH
S
O
O
S
N +
HO
O
NYC92338
NYC 292005
Fig. 4 Chemical structures of compounds used in retests (see above)
 
Search WWH ::




Custom Search