Screening Library of Serine Hydrolase Inhibitors

Working with Serine Hydrolase Inhibitors

The advertised selection of serine hydrolase inhibitors, developed by the Boger group, represents a small, but powerful library of urea-derived molecules that can bind irreversibly to the target enzyme by active site carbamoylation of the catalytic serine.1 There are approximately 240 different human serine hydrolases, of which only half have been characterized to date and a majority still lack selective inhibitors to aid in the identification of the enzyme’s role or targeted substrates.2-3 It has been shown that the reactivity and selectivity of the inhibitors can be tuned by changing substituents in the leaving group (head group, aniline or pyrazole), by the use of different linker domains (cyclic and acyclic diamines or piperidine), or by attaching different groups to the Boc-protected nitrogen of the linker (Figure 2 and 3).1

serine hydrolase screening library

Advantages

  • Library of irreversible serine hydrolase inhibitors may serve as initial leads for in vivo pharmaceutical probes to define the function of an uncharacterized serine hydrolase.
  • The compounds can be used as building blocks to create novel inhibitors for this class of enzymes.
  • Boc-protected amines can be derivatized to install a side chain with active site recognition features, while simultaneously improving potency and selectivity for targeted serine hydrolase.

Representative Schemes and Applications

Figure 2 shows a small SAR study of 44 compounds (3 head groups x 3 linker domains  and multiple diversification groups). These were tested on eight serine hydrolases for the three different head groups, 2-aminopyridine (2-AP), 4-trifluoromethylaniline (4-TFMA), and 2-fluoroaniline (2-FA) as well as the three different central linker diamines, the six-membered cyclic diamine (6-CDA), the seven-membered cyclic diamine (7-CDA), and the acyclic diamine (ACDA).1 The % inhibition of the various derivatives (tested at 5 µM) of each category (head group, central linker) have been added up to show a trend.

Head Group Comparison of 8 Serine Hydrolases

Central Linker Diamine Comparison of 8 Serine Hydrolases

Figure 2 Comparison of the summed up % inhibition of the three head groups and the three central linkers on eight serine hydrolases.

The serine hydrolase ABHD6-2 shows a clear trend for both the head group aniline and the linker domain. According to this trend the serine hydrolase inhibitor 7 (SHI-7) has the best head group and linker domain combination for developing inhibitors of the enzyme ABHD6-2 (Figure 3).

Serine hydrolase ABHD6-2 inhibition with different head groups and linker domains

Figure 3 Observed trends for ABHD6-2 inhibition with different head groups (top) and linker domains (bottom).

 

Special thanks to Manuela Brutsch, Aleksandar Radakovic, and Dale Boger for contributing this technology spotlight.

 

Related Definitions

Hydrolases are enzymes that catalyze hydrolysis or use water when breaking chemical bonds. Esterases, glycosidases, lipases, nucleosidases, and proteases are all common hydrolases.

Serine hydrolase is one such class of enzyme identifiable by a nucleophilic serine on its active site.

A hydrolase inhibitor is a compound that limits enzymatic activity of a hydrolase. Several hydrolase inhibitors have been studied as therapeutics where they have potential against inflammation, pain, hypertension, diabetes, and heart diease. They are also thought to confer protective effects against brain, cardiac, and renal injury.

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