ML152 : GALK1 (Galactokinase) Inhibitor
ML152
Target Name
Galactokinase
Target Alias
GALK1
Target Class
Carbohydrate Kinase
Mechanism of Action
Inhibitor of GALK1
Biological / Disease Relevance
Classic Galactosemia
In vitro activity
GALK bioassay (IC50)Target Information
Classic Galactosemia is a potentially lethal disease caused by deficient galactose-1-phosphate uridyltransferase (GALT) that results in the buildup of galactose-1-phosphate (gal-1-P) in the blood. Galactokinase (GALK) is the enzyme responsible for converting galactose into gal-1-p. A pharmacological inhibitor of GALK is therefore sought for a potential therapy for galactosemia by reducing levels of gal-1-P. The probe developed herein inhibits GALK with a potency of 1.0μM in a luminescence based biochemical assay and should be useful for studying the role of GALK modulation in the progression of Classic Galactosemia.
Properties
ML152
NCGC00187642
| Physical & chemical properties | ||||
|---|---|---|---|---|
| Molecular Weight | 336.4 g/mol | |||
| Molecular Formula | C19H20N4O2 | |||
| cLogP | 2.1 | |||
| PSA | 79.5 | |||
| Storage | ||||
| Solubility | 10mM in DMSO | |||
| CAS Number | ||||
SMILES:
O=C1CCCC2=C1C3(NC(NC4=NC5=CC=CC=C5O4)=N2)CCCC3
InChI:
InChI=1S/C19H20N4O2/c24-14-8-5-7-13-16(14)19(10-3-4-11-19)23-17(20-13)22-18-21-12-6-1-2-9-15(12)25-18/h1-2,6,9H,3-5,7-8,10-11H2,(H2,20,21,22,23)
InChIKey:
FDNVTCDQGOVLPM-UHFFFAOYSA-N
Activity
Summary activity statement /
ML152 (CID 664331; SID 87550830) is identified as a selective inhibitor of GALK. This probe is an advancement over previously reported inhibitors, which were all non-selective electrophilic Michael acceptors, and/or redox active compounds, which likely engender a promiscuous activity profile. ML152 is selective for GALK vs. 4-Diphosphocytidyl-2-C-methylerythritol (CDP-ME; a related kinase in the GHMP family), as well as other kinase assays run to date at the NIH Chemical Genomics Center. ML152 did not show activity in 42 unique assays, including both biochemical and cell-based assays.
In vitro activity - Selectivity Assay
| ML152 (IC50) | |
|---|---|
|
GALK |
1 uM |
|
CDP-Me (CMK) |
> 10 uM |
|
Redox Assay |
Inactive |
|
Cytotoxicity |
Not toxic |
Summary /
ML152 is observed to be active against GALK with an IC50 of 1μM but inactive against CDP-Me kinase. Results showed no redox or cytotoxic activity of the compound (cytotoxicity was determined after 48 hours). All assays were performed at least in duplicate on at least two separate days.
Figure 1. Potency and selectivity of ML152 against GALK and other counter and secondary screens.
In vitro activity - Mechanism of Action
Summary /
The mechanism of action of ML152 was determined via substrate competition and kinetic assays. Results are consistent with the lead compound being ATP competitive.
Figure 2. Substrate competition with ML152. A) Kinase reaction run at two different ATP concentrations, while keeping the galactose concentration at KM, showed increase in potency of the compound as exhibited by a left shift of the dose-response curve of the ATP competition assay. B) No significant change in the IC50 / potency of the lead was observed in the presence of three different galactose concentrations run at KM concentration of ATP. C) Dose response kinetics study of the lead compound. KM of ATP increased as concentration of the inhibitor increased but the KM for galactose remained the same; hence further showing a potential ATP competition.
References
- qHTS Assay for Inhibitors of Human Galactokinase (GALK): Summary
- Boxer MB, Shen M, Tanega C, et al. Toward Improved Therapy for Classic Galactosemia. 2010 Mar 18 [Updated 2011 Mar 3]. In: Probe Reports from the NIH Molecular Libraries Program [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2010
- Lai K, Boxer MB, Marabotti A. GALK inhibitors for classic galactosemia. Future Med Chem. 2014;6(9):1003-1015. doi:10.4155/fmc.14.43