Toward RNase inhibitors: thermodynamics of 2'-CMP/RNase-A binding in multi-ion buffer.
Certain ribonucleases (RNases), such as eosinophil-derived neurotoxin, are associated with pathological conditions (e.g. asthma and inflammatory bowel disease) and can even be overtly cyto(neuro)toxic. It has been proposed that small-molecule inhibitors should have therapeutic utility. We used isothermal titration microcalorimetry to characterize reversible inhibitor cytidine 2'-monophosphate (2'-CMP) binding to RNase-A in a multi-ion buffer at 37 degrees as a representative system. The estimated parameters were: K(d)=13.9 microM; DeltaG degrees =-6.90 kcal/mol; DeltaH degrees =-15.7 kcal/mol; and DeltaS degrees =-0.028 kcal/mol-K ('enthalpy-driven' interaction). These data should assist drug design of small-molecule inhibitors of homologous RNase catalytic domains.
Raffa
Robert B
RB
Department of Pharmaceutical Sciences, School of Pharmacy, Temple University, 3307 N. Broad Street, Philadelphia, PA 19140, USA. rraffa@temple.edu
Spencer
Shawn D
SD
Schulingkamp
Robert J
RJ
D000818:Animals; D001665:Binding Sites; D002021:Buffers; D002417:Cattle; D003568:Cytidine Monophosphate / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008670:Metals / Q000378:metabolism; D012259:Ribonuclease, Pancreatic / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013816:Thermodynamics
D002021:Buffers; D004791:Enzyme Inhibitors; D008670:Metals; D012259:Ribonuclease, Pancreatic; D003568:Cytidine Monophosphate