Toward RNase inhibitors: thermodynamics of 2′-CMP/RNase-A binding in multi-ion buffer

• Published in: Biochemical pharmacology Vol. 63; no. 11; pp. 1937 - 1939
• Main Authors: Raffa, Robert B, Spencer, Shawn D, Schulingkamp, Robert J
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.06.2002; Elsevier Science
• Subjects: Animals; Binding Sites; Biological and medical sciences; Bones, joints and connective tissue. Antiinflammatory agents; Buffers; Cattle; Cytidine Monophosphate - pharmacology; Enzyme Inhibitors - pharmacology; Medical sciences; Metals - metabolism; Microcalorimetry; Pharmacology. Drug treatments; Ribonuclease, Pancreatic - antagonists & inhibitors; Ribonuclease, Pancreatic - metabolism; RNase; Thermodynamics; and RNase, ribonuclease; Thermodynamics; 2′-CMP, cytidine 2′-monophosphate; ITC, isothermal (micro)calorimetry; K d , dissociation constant; Ac, acetate; Microcalorimetry; RNase; Respiratory disease; Enzyme; Toxicity; Antiinflammatory agent; Enzyme inhibitor; Molecular interaction; Esterases; Cytidine; Asthma; Biological fixation; Hydrolases; Obstructive pulmonary disease; Pancreatic ribonuclease
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/S0006-2952(02)00977-2

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° as a representative system. The estimated parameters were: K d =13.9 μM; Δ G°=−6.90 kcal/mol; Δ H°=−15.7 kcal/mol; and Δ S°=−0.028 kcal/mol-K (‘enthalpy-driven’ interaction). These data should assist drug design of small-molecule inhibitors of homologous RNase catalytic domains.