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BioAssay: AID 1466

qHTS Assay for Inhibitors of Human alpha-Glucosidase as a Potential Chaperone Treatment of Pompe Disease

Alpha-glucosidase is responsible for hydrolysis of terminal, non-reducing 1,4-linked alpha-D-glucose residues with release of alpha-D-glucose. It is a lysosomal hydrolase that is required for the degradation of a small percentage (1-3%) of cellular glycogen in human. Deficiency of this enzyme results in glycogen-storage disease type II (GSDII), also referred to as Pompe disease, an autosomal more ..
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 Tested Compounds
 Tested Compounds
All(199174)
 
 
Active(10)
 
 
Inactive(183383)
 
 
Inconclusive(15794)
 
 
 Tested Substances
 Tested Substances
All(199303)
 
 
Active(10)
 
 
Inactive(183498)
 
 
Inconclusive(15795)
 
 
AID: 1466
Data Source: NCGC (ALGU004)
BioAssay Type: Confirmatory, Concentration-Response Relationship Observed
Depositor Category: NIH Molecular Libraries Probe Production Network
BioAssay Version:
Deposit Date: 2008-12-30
Modify Date: 2010-01-12

Data Table ( Complete ):           Active    All
Target
BioActive Compounds: 10
Depositor Specified Assays
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AIDNameTypeProbeComment
997Counterscreen for Glucocerebrosidase Inhibitors: qHTS Assay for Rice alpha-Glucosidase at pH 5.0confirmatory
2100qHTS Assay for Inhibitors and Activators of Human alpha-Glucosidase Cleavage of Glycogenconfirmatory
2242qHTS Assay for Activators of Human alpha-Glucosidase as a Potential Chaperone Treatment of Pompe Diseaseconfirmatory
2112qHTS Assay for Inhibitors and Activators of Human alpha-Glucosidase From Spleen Homogenateconfirmatory
2110Confirmation of Inhibitors and Activators of Purified Human alpha-Glucosidase Using an Alternate Red Fluorescent Susbtrateconfirmatory
2111Confirmation of Inhibitors and Activators of Human alpha-Glucosidase From Spleen Homogenate Using an Alternate Red Fluorescent Susbtrateconfirmatory
1473Quantitative High-Throughput Screen for Inhibitors and Activators of Human alpha-Glucosidase as a Potential Chaperone Treatment of Pompe Disease: Summarysummary1
2113Confirmation of Inhibitors and Activators of Human alpha-Glucosidase From Spleen Homogenateconfirmatory
2293Direct Measure of the Activation of Acid alpha-Glucosidase Catalytic Rateother
2641qHTS Assay for Inhibitors of Human alpha-Glucosidase as a Potential Chaperone Treatment of Pompe Disease: Stabilizers of Alpha-Glucosidase Under Thermal Denaturation Conditionsother
Description:
NIH Chemical Genomics Center [NCGC]
NIH Molecular Libraries Probe Production centers Network [MLPCN]

MLPCN Grant: 1R03MH084841-01
Assay Submitter (PI): Wei Zheng

NCGC Assay Overview:

Alpha-glucosidase is responsible for hydrolysis of terminal, non-reducing 1,4-linked alpha-D-glucose residues with release of alpha-D-glucose. It is a lysosomal hydrolase that is required for the degradation of a small percentage (1-3%) of cellular glycogen in human. Deficiency of this enzyme results in glycogen-storage disease type II (GSDII), also referred to as Pompe disease, an autosomal recessive disorder. Structurally normal glycogen is accumulated in lysosomes and cytoplasm in affected patients, primarily in muscle tissues. Excessive glycogen storage within lysosomes may interrupt normal functioning of other organelles and leads to cellular injury. In turn, this leads to enlargement and dysfunction of the entire organ involved (eg, cardiomyopathy and muscle weakness).

It has reported that the improper folding and trafficking of alpha-glucosidase resulting from the genetic mutations may account for a significant number of Pompe patients. N-butyl-deoxynojirimycin, an inhibitor of alpha-glucosidase, was reported to exhibit the pharmacological chaperone activity, which significantly increases the mutant enzyme activity in cells. We optimized this alpha-glucosidase assay in 1536-well plate format for identifying the novel small molecule inhibitors with the structures other than the sugar analogs in order to develop the new pharmacological chaperones.
Protocol
NCGC Assay Protocol Summary:

This is a fluorogenic enzyme assay with 4-methylumbelliferyl-alpha-D-pyranoside as the substrate and human alpha-glucosidase as the enzyme preparation. Upon the hydrolysis of this fluorogenic substrate, the resulting product, 1. 4-methyllumbelliferone, can be excited at 365 nm and emits at 440 nm which can be detected by a standard fluorescence plate reader. Data were normalized to the controls for basal activity (without enzyme) and 100% activity (with enzyme). In the AC50 values were determined from concentration-response data modeled with the standard Hill equation.

Assay buffer: 50 mM citric acid (titrated with potassium phosphate to pH 5.0), 0.005% Tween-20, pH 5.0. (pH 5.0 is an optimal condition for this enzyme assay)


1536-well assay protocol for the human alpha-glucosidase:
(1) Add 2 ul/well of enzyme (4 nM final)
(2) Add 23 nL compounds in DMSO solution. The final titration was 0.7 nM to 77 uM.
(3) Add 1 ul of substrate (400 uM final)
(4) Incubate at room temperature for 20 min.
(5) Add 2 ul stop solution (1M NaOH and 1M Glycine mixture, pH 10)
(6) Detect the assay plate in a ViewLux plate reader (PerkinElmer) with Ex=365 nm and Em=440nm.

Keywords: Alpha-glucosidase, Pompe Disease, pharmacological chaperone, chaperone therapy, high throughput screening, alpha-glucosidase inhibitor, MLSMR, MLSCN, NIH Roadmap, qHTS and NCGC
Comment
Compound Ranking:

1. Compounds are first classified as having full titration curves, partial modulation, partial curve (weaker actives), single point activity (at highest concentration only), or inactive. See data field "Curve Description". For this assay, apparent inhibitors are ranked higher than compounds that showed apparent activation.
2. For all inactive compounds, PUBCHEM_ACTIVITY_SCORE is 0. For all active compounds, a score range was given for each curve class type given above. Active compounds have PUBCHEM_ACTIVITY_SCORE between 40 and 100. Inconclusive compounds have PUBCHEM_ACTIVITY_SCORE between 1 and 39. Fit_LogAC50 was used for determining relative score and was scaled to each curve class' score range.
Result Definitions
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TIDNameDescriptionHistogramTypeUnit
OutcomeThe BioAssay activity outcomeOutcome
ScoreThe BioAssay activity ranking scoreInteger
1PhenotypeIndicates type of activity observed: inhibitor, activator, fluorescent, cytotoxic, inactive, or inconclusive.String
2Potency*Concentration at which compound exhibits half-maximal efficacy, AC50. Extrapolated AC50s also include the highest efficacy observed and the concentration of compound at which it was observed.FloatμM
3EfficacyMaximal efficacy of compound, reported as a percentage of control. These values are estimated based on fits of the Hill equation to the dose-response curves.Float%
4Analysis CommentAnnotation/notes on a particular compound's data or its analysis.String
5Curve_DescriptionA description of dose-response curve quality. A complete curve has two observed asymptotes; a partial curve may not have attained its second asymptote at the highest concentration tested. High efficacy curves exhibit efficacy greater than 80% of control. Partial efficacies are statistically signficant, but below 80% of control.String
6Fit_LogAC50The logarithm of the AC50 from a fit of the data to the Hill equation (calculated based on Molar Units).Float
7Fit_HillSlopeThe Hill slope from a fit of the data to the Hill equation.Float
8Fit_R2R^2 fit value of the curve. Closer to 1.0 equates to better Hill equation fit.Float
9Fit_InfiniteActivityThe asymptotic efficacy from a fit of the data to the Hill equation.Float%
10Fit_ZeroActivityEfficacy at zero concentration of compound from a fit of the data to the Hill equation.Float%
11Fit_CurveClassNumerical encoding of curve description for the fitted Hill equation.Float
12Excluded_PointsWhich dose-response titration points were excluded from analysis based on outlier analysis. Each number represents whether a titration point was (1) or was not (0) excluded, for the titration series going from smallest to highest compound concentrations.String
13Max_ResponseMaximum activity observed for compound (usually at highest concentration tested).Float%
14Activity at 0.123 uM (0.123077μM**)% Activity at given concentration.Float%
15Activity at 0.615 uM (0.615385μM**)% Activity at given concentration.Float%
16Activity at 3.077 uM (3.07692μM**)% Activity at given concentration.Float%
17Activity at 15.38 uM (15.3846μM**)% Activity at given concentration.Float%
18Activity at 76.92 uM (76.9231μM**)% Activity at given concentration.Float%
19Compound QCNCGC designation for data stage: 'qHTS', 'qHTS Verification', 'Secondary Profiling'String

* Activity Concentration. ** Test Concentration.
Additional Information
Grant Number: 1R03MH084841-01

Data Table (Concise)
Classification
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