The relevance of K-i calculation for bi-substrate enzymes illustrated by kinetic evaluation of a novel lysine (K) acetyltransferase 8 inhibitor

作者：Wapenaar Hannah; van den Bosch Thea; Leus Niek G J; van der Wouden Petra E; Eleftheriadis Nikolaos; Hermans Jos; Hailu Gebremedhin Solomon; Rotili Dante; Mai Antonello; Domling Alexander; Bischoff Rainer; Haisma Hidde J; Dekker Frank J^*

来源：European Journal of Medicinal Chemistry, 2017, 136: 480-486.

DOI：10.1016/j.ejmech.2017.05.015

• Histone acetyltransferases
• KAT8
• Fragment screening
• Histone acetylation
• Inhibitor
• Enzyme kinetics

Histone acetyltransferases (HATs) are important mediators of epigenetic post-translational modifications of histones that play important roles in health and disease. A disturbance of these modifications can result in disease states, such as cancer or inflammatory diseases. Inhibitors of HATs (HATi) such as lysine (K) acetyltransferase 8 (KAT8), could be used to study the epigenetic processes in diseases related to these enzymes or to investigate HATs as therapeutic targets. However, the development of HATi is challenged by the difficulties in kinetic characterization of HAT enzymes and their inhibitors to enable calculation of a reproducible inhibitory potency. In this study, a fragment screening approach was used, enabling identification of 4-amino-1-naphthol, which potently inhibited KAT8. The inhibitor was investigated for enzyme inhibition using kinetic and calorimetric binding studies. This allowed for calculation of the K-i values for both the free enzyme as well as the acetylated intermediate. Importantly, it revealed a striking difference in binding affinity between the acetylated enzyme and the free enzyme, which could not be revealed by the IC50 value. This shows that kinetic characterization of inhibitors and calculation of K-i values is crucial for determining the binding constants of HAT inhibitors. We anticipate that more comprehensive characterization of enzyme inhibition, as described here, is needed to advance the field of HAT inhibitors.

• 出版日期2017-8-18