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ChEMBL has recently begun to display the ‘AIDX’ field as part of our assay data. In this Blog post you can find out more about the AIDX as well as how to best populate this field when depositing data to ChEMBL.

What is the AIDX?

ChEMBL extracts bioactivity data from the core medicinal literature but also accepts deposited data from the scientific community. In fact, deposited data now provides more than half of the bioactivity data within ChEMBL. During the preparation of data for submission to ChEMBL, depositors format and assign identifiers to their data to allow integration into ChEMBL and the AIDX is the depositor-defined identifier for assays. Each AIDX corresponds to a distinct assay with a defined experimental set-up (aim, target and method). Concise and meaningful AIDXs are ideal since these are not easily replicated by different depositors.


Suggested AIDX format: Smith_KinaseXYZ_Assay36 (abbreviation of the group leader, target, assay number).

Poor AIDX format: ‘1’, ‘2’, ‘3’

Reuse of AIDXs - depositing additional bioactivity data to an existing assay

Depositors occasionally submit additional bioactivity data for assays that already exist within ChEMBL. For example when a single institute is performing the same set of assays for newly synthesised compounds, or a contract research organisation is characterising compounds using a defined set of assays. Here, depositors can reuse an existing AIDX for new bioactivity data, but the AIDX must match the previous identifier exactly and the assay set up should be identical. Depositors are responsible for ensuring that the assay set up is consistent between datasets and that a standard protocol and appropriate positive and negative controls are included to ensure variation is within expected limits.

Can I reuse an existing depositor AIDX if my assay uses the same commercial screening kit?

Commercial kits may have a standard assay set up but we consider assays run by different institutions, using the same commercial kit, as distinct. The depositor AIDXs for these screening assays should be distinct if performed at different institutes. However, to allow comparison between similar assays, kit identifiers/catalogue numbers should ideally be included within the assay description.

e.g. Inhibition of XYZ target at 10uM tested using the Eurofins SafetyScreen44 (BI) (P270) - P270 is the catalogue number.


Overall, the AIDX is an identifier that depositors use when submitting experimental data to ChEMBL. Occasionally, this identifier can be re-used for data from a single institute or from CROs. Assays from different institutes are considered distinct but we suggest that users include a catalogue number for commercial kits to facilitate comparisons across similar assays.

Questions? Get in touch in the Helpdesk with any further questions or browse our assays.


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