Recombinant Human ADH1A Protein: Properties & Research Uses

Recombinant Human Alcohol Dehydrogenase/ADH1A Protein is a key hepatic enzyme involved in the oxidative metabolism of ethanol and a broad range of endogenous and exogenous alcohols, making it an essential tool for biochemical, toxicological, and drug metabolism research.

Protein Name

Recombinant Human Alcohol Dehydrogenase/ADH1A Protein

SKU

rp364724

Gene Name

ADH1A

Protein Family

Alcohol Dehydrogenase (ADH) family, class I

Primary Biological Function

Catalyzes the NAD⁺-dependent oxidation of ethanol to acetaldehyde and reduction of aldehydes to alcohols

Primary Expression Site

Liver (hepatic tissue)

Cofactor

NAD⁺/NADH

What Is ADH1A? Gene, Protein, and Biological Context

Alcohol Dehydrogenase 1A (ADH1A) is a member of the class I alcohol dehydrogenase subfamily, encoded by the ADH1A gene located on chromosome 4q22–23 in humans. The ADH family comprises a central group of zinc-containing enzymes responsible for the interconversion of alcohols and aldehydes or ketones, utilizing NAD⁺ or NADH as cofactors.

ADH1A is predominantly expressed in the liver, where it plays a principal role in the first-pass metabolism of ethanol. Beyond ethanol, ADH1A acts on a range of primary and secondary alcohols, contributing to the metabolism of retinol (vitamin A), fatty alcohols, and various xenobiotic substrates. This broad substrate range makes ADH1A relevant not only to alcohol research but also to studies of vitamin A metabolism and endogenous lipid processing.

Class I ADH enzymes, including ADH1A, ADH1B, and ADH1C, are homodimeric or heterodimeric proteins with each subunit coordinating two zinc ions: one structural and one catalytic. The catalytic zinc ion is positioned within the active site and is essential for substrate binding and catalysis.

Mechanism of Action and Enzymatic Properties

ADH1A catalyzes the reversible oxidation-reduction reaction between alcohols and their corresponding aldehydes or ketones. The canonical reaction in ethanol metabolism is:

Ethanol + NAD⁺ ⇌ Acetaldehyde + NADH + H⁺

This reaction proceeds via an ordered bi-bi kinetic mechanism. NAD⁺ binds first to the enzyme, followed by the alcohol substrate. After hydride transfer from the substrate to NAD⁺, the aldehyde product is released before NADH dissociates. The catalytic zinc ion in the active site coordinates the hydroxyl group of the alcohol substrate, facilitating hydride transfer.

ADH1A is considered a low-K_m enzyme for ethanol relative to some other isoforms, allowing it to function effectively at lower alcohol concentrations. Its activity can be inhibited by 4-methylpyrazole (fomepizole), a competitive inhibitor used clinically to treat methanol and ethylene glycol poisoning, as well as by disulfiram-related compounds.

The enzyme requires zinc as an essential metal cofactor. Chelating agents that remove zinc will abolish enzymatic activity. Activity is typically measured spectrophotometrically by monitoring the production of NADH at 340 nm.

Research Applications of Recombinant Human ADH1A Protein

Recombinant Human ADH1A Protein (SKU: rp364724) is a versatile reagent supporting a broad spectrum of research and assay development applications:

• Enzyme Activity Assays: Recombinant ADH1A serves as a positive control or analytical standard in spectrophotometric assays measuring NAD⁺-dependent alcohol oxidation. Researchers can use it to validate assay conditions, determine inhibitor IC₅₀ values, and benchmark novel ADH substrates.
• Drug Metabolism and Pharmacokinetics (DMPK): As ethanol and many pharmaceutical compounds are ADH substrates, recombinant ADH1A is used to study first-pass hepatic metabolism and to screen drug candidates for ADH-mediated metabolic liability.
• Inhibitor Screening: The protein is suitable for high-throughput screening (HTS) of potential ADH1A inhibitors, relevant to the development of treatments for alcohol use disorder or toxic alcohol poisoning.
• Structural and Biophysical Studies: Recombinant ADH1A supports crystallography, cryo-EM, and biophysical interaction studies to elucidate enzyme-substrate and enzyme-inhibitor binding modes.
• Retinol and Vitamin A Metabolism Research: Given ADH1A's documented activity toward retinol, the recombinant protein can be employed in studies of retinoic acid biosynthesis pathways.
• Antibody Validation and Western Blot Standards: Purified recombinant protein provides a well-characterized antigen for validating anti-ADH1A antibodies and serving as a molecular weight standard in immunoblotting.

Handling, Storage, and Quality Considerations

To maintain the activity and integrity of Recombinant Human ADH1A Protein, adhere to the following general best practices. Always consult the product datasheet (absea#PP-111) for lot-specific specifications:

• Storage: Store lyophilized or liquid recombinant protein at –20 °C or –80 °C as indicated on the datasheet. Avoid repeated freeze-thaw cycles, which can lead to protein aggregation and loss of enzymatic activity. Aliquot the protein upon first thaw.
• Reconstitution: Reconstitute lyophilized preparations in the buffer recommended by the supplier. Allow the protein to equilibrate to room temperature before reconstitution to minimize precipitation.
• Working Conditions: ADH activity assays are typically conducted at physiological pH (7.0–7.5) in the presence of NAD⁺. Avoid the use of strong chelators such as EDTA in assay buffers, as these may chelate catalytic zinc and inhibit enzyme activity.
• Quality Control: Aladdin Scientific recombinant proteins undergo standard QC including SDS-PAGE for purity assessment and functional activity assays where applicable. Refer to the Certificate of Analysis (CoA) provided with each lot for verified purity, activity, and endotoxin data.

If you require custom formulations, bulk quantities, or specific activity guarantees, contact Aladdin Scientific technical support for assistance.

Frequently asked questions

What is the biological function of ADH1A?

ADH1A (Alcohol Dehydrogenase 1A) catalyzes the NAD⁺-dependent oxidative metabolism of ethanol to acetaldehyde in the liver. It also acts on other primary and secondary alcohols, including retinol, making it important in vitamin A metabolism and the processing of various endogenous and xenobiotic substrates.

How should I measure ADH1A enzymatic activity in vitro?

ADH1A activity is commonly measured spectrophotometrically by monitoring the increase in absorbance at 340 nm, which corresponds to NADH production from the NAD⁺-dependent oxidation of ethanol or another alcohol substrate. Reactions are typically carried out at physiological pH (7.0–7.5) in an appropriate buffer free of metal chelators such as EDTA. A standard curve or defined enzyme unit definition provided in the product CoA should be used for quantification.

Can Recombinant Human ADH1A Protein be used for inhibitor screening?

Yes. Recombinant Human ADH1A Protein (SKU: rp364724) is well-suited for inhibitor screening assays, including high-throughput formats. The spectrophotometric NADH-production assay at 340 nm is readily adaptable to microplate readers, enabling IC₅₀ determination for candidate inhibitors. Known inhibitors such as 4-methylpyrazole (fomepizole) can be used as positive controls to validate assay performance.

Why is ADH1A considered a class I alcohol dehydrogenase?

ADH1A belongs to the class I subfamily of the medium-chain dehydrogenase/reductase (MDR) superfamily, characterized by its dimeric structure, dependence on zinc as a catalytic cofactor, and high expression in liver tissue. Class I enzymes (ADH1A, ADH1B, ADH1C) are distinguished from other classes by their substrate specificity, kinetic parameters, and gene cluster organization on chromosome 4q.

How should Recombinant Human ADH1A Protein be stored to preserve activity?

Store the protein according to the conditions specified on the product datasheet and Certificate of Analysis. Generally, recombinant proteins should be stored at –20 °C or –80 °C and repeated freeze-thaw cycles should be avoided. Upon first thaw, aliquot the protein into single-use volumes to maximize shelf life and maintain enzymatic activity.

References

1. Duester G, Farres J, Felder MR, et al. Recommended nomenclature for the vertebrate alcohol dehydrogenase gene family. Biochem Pharmacol. 1999;58(3):389-395.
2. Edenberg HJ. The genetics of alcohol metabolism: role of alcohol dehydrogenase and aldehyde dehydrogenase variants. Alcohol Res Health. 2007;30(1):5-13.
3. Hurley TD, Edenberg HJ. Genes encoding enzymes involved in ethanol metabolism. Alcohol Res. 2012;34(3):339-344.
4. Aladdin Scientific. Recombinant Human Alcohol Dehydrogenase/ADH1A Protein. Product datasheet absea#PP-111. SKU: rp364724.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.