TY - JOUR
T1 - Cyclic adenosine 5′-diphosphate ribose analogs without a southern ribose inhibit ADP-ribosyl cyclase-hydrolase CD38
AU - Swarbrick, Joanna M.
AU - Graeff, Richard
AU - Zhang, Hongmin
AU - Thomas, Mark P.
AU - Hao, Quan
AU - Potter, Barry V L
PY - 2014/10/23
Y1 - 2014/10/23
N2 - Cyclic adenosine 5′-diphosphate ribose (cADPR) analogs based on the cyclic inosine 5′-diphosphate ribose (cIDPR) template were synthesized by recently developed stereo- and regioselective N1-ribosylation. Replacing the base N9-ribose with a butyl chain generates inhibitors of cADPR hydrolysis by the human ADP-ribosyl cyclase CD38 catalytic domain (shCD38), illustrating the nonessential nature of the southern ribose for binding. Butyl substitution generally improves potency relative to the parent cIDPRs, and 8-amino-N9-butyl-cIDPR is comparable to the best noncovalent CD38 inhibitors to date (IC50 = 3.3 μM). Crystallographic analysis of the shCD38:8-amino-N9-butyl-cIDPR complex to a 2.05 Å resolution unexpectedly reveals an N1-hydrolyzed ligand in the active site, suggesting that it is the N6-imino form of cADPR that is hydrolyzed by CD38. While HPLC studies confirm ligand cleavage at very high protein concentrations, they indicate that hydrolysis does not occur under physiological concentrations. Taken together, these analogs confirm that the "northern" ribose is critical for CD38 activity and inhibition, provide new insight into the mechanism of cADPR hydrolysis by CD38, and may aid future inhibitor design.
AB - Cyclic adenosine 5′-diphosphate ribose (cADPR) analogs based on the cyclic inosine 5′-diphosphate ribose (cIDPR) template were synthesized by recently developed stereo- and regioselective N1-ribosylation. Replacing the base N9-ribose with a butyl chain generates inhibitors of cADPR hydrolysis by the human ADP-ribosyl cyclase CD38 catalytic domain (shCD38), illustrating the nonessential nature of the southern ribose for binding. Butyl substitution generally improves potency relative to the parent cIDPRs, and 8-amino-N9-butyl-cIDPR is comparable to the best noncovalent CD38 inhibitors to date (IC50 = 3.3 μM). Crystallographic analysis of the shCD38:8-amino-N9-butyl-cIDPR complex to a 2.05 Å resolution unexpectedly reveals an N1-hydrolyzed ligand in the active site, suggesting that it is the N6-imino form of cADPR that is hydrolyzed by CD38. While HPLC studies confirm ligand cleavage at very high protein concentrations, they indicate that hydrolysis does not occur under physiological concentrations. Taken together, these analogs confirm that the "northern" ribose is critical for CD38 activity and inhibition, provide new insight into the mechanism of cADPR hydrolysis by CD38, and may aid future inhibitor design.
UR - http://www.scopus.com/inward/record.url?scp=84908374193&partnerID=8YFLogxK
UR - http://dx.doi.org/10.1021/jm501037u
U2 - 10.1021/jm501037u
DO - 10.1021/jm501037u
M3 - Article
AN - SCOPUS:84908374193
VL - 57
SP - 8517
EP - 8529
JO - Journal of Medicinal Chemistry
JF - Journal of Medicinal Chemistry
SN - 0022-2623
IS - 20
ER -