Inhibition of thermolysin and neutral endopeptidase 24.11 by a novel glutaramide derivative: X-ray structure determination of the thermolysin-inhibitor complex

• Published in: Biochemistry (Easton) Vol. 33; no. 1; pp. 51 - 56
• Main Authors: Holland, D. R, Barclay, P. L, Danilewicz, J. C, Matthews, B. W, James, K
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 11.01.1994
• Subjects: Amino Acid Sequence; Biological and medical sciences; Cardiotonic agents; Cardiovascular system; Cyclohexanecarboxylic Acids - chemistry; Cyclohexanecarboxylic Acids - pharmacology; Cyclopentanes - chemistry; Cyclopentanes - pharmacology; Dipeptides - chemistry; Dipeptides - pharmacology; Glycopeptides - chemistry; Glycopeptides - pharmacology; Kinetics; Medical sciences; Models, Molecular; Molecular Sequence Data; Molecular Structure; Neprilysin - antagonists & inhibitors; Neprilysin - chemistry; Pharmacology. Drug treatments; Protein Conformation; Thermolysin - antagonists & inhibitors; Thermolysin - chemistry; Tryptophan - analogs & derivatives; Tryptophan - chemistry; Tryptophan - pharmacology; X-Ray Diffraction - methods; Cardiotonic agent; Enzyme; Metalloendopeptidases; Inhibitor enzyme complex; Thermolysin; Prodrug; Analog; Hydrolases; Neprilysin; Mechanism of action; Proteinases; Structural analysis; Crystalline structure
• DOI: 10.1021/bi00167a007
• ISSN: 0006-2960

Determination of the X-ray structure of thermolysin-inhibitor complexes has proven useful in aiding our understanding of the mode of binding of inhibitors of related, physiologically important, mammalian zinc peptidases including neutral endopeptidase EC 3.4.24.11 and angiotensin-converting enzyme. Here we describe the mode of binding to crystalline thermolysin of N-[1-(2(R,S)-carboxy-4-phenylbutyl)-cyclopentylcarbonyl]-(S) -tryptophan (CCT). CCT is an analogue of both candoxatrilat, a potent inhibitor of neutral endopeptidase 24.11, and of the 5-indanyl ester prodrug candoxatril, which is under clinical evaluation as a potential therapy for congestive heart failure. CCT differs from the previously studied N-carboxyalkyl dipeptide CLT [N-(S)-(1-carboxy-3-phenylpropyl)-(S)-leucyl-(S)-tryptophan] in several important respects. It has a highly constrained gem-cyclopentyl P1' substituent and lacks the characteristic imino nitrogen substituent of CLT. The structure determination shows that, notwithstanding the conformational influence of the gem-cyclopentyl substituent, CCT binds within the active site of thermolysin in a similar manner to CLT. Although the characteristic hydrogen bond between the imino nitrogen of CLT and thermolysin is absent in CCT, the affinities of the two inhibitors for the enzyme are virtually identical. These results illustrate the importance of considering not only those hydrogen bonds that are formed in an enzyme-ligand complex but also the other hydrogen bonds that may be lost due to desolvation of the enzyme and ligand on formation of the complex. In addition, the overall conformational demands placed upon a ligand in order to achieve receptor interaction may be critically important.