What is IMPDH Type 2 and what is its biological significance?

IMPDH Type 2 (IMPDH2) is a key enzyme in the de novo biosynthesis of guanine nucleotides. It converts inosine 5'-monophosphate (IMP) to xanthosine 5'-monophosphate (XMP), which is a crucial step in the production of GTP and dGTP. This enzyme is particularly important in rapidly dividing cells and is a validated target for immunosuppressive, antiviral, and anticancer therapies.

What are the main applications of Human IMPDH2?

Human IMPDH2 is widely used in drug discovery for cancer and autoimmune diseases, antiviral research, nucleotide metabolism studies, and high-throughput screening of potential enzyme inhibitors. It's particularly valuable for studying the mechanism of action of immunosuppressants like mycophenolic acid and ribavirin.

What quality controls are performed on the IMPDH2 enzyme?

Each batch of Human IMPDH2 undergoes rigorous quality control including: activity assays to ensure specific activity, SDS-PAGE analysis for purity assessment, endotoxin testing, and functional validation in inhibitor screening assays. The enzyme is provided with a detailed Certificate of Analysis.

What is the recommended storage and handling for IMPDH2?

The lyophilized enzyme should be stored at -20°C. Upon reconstitution, the enzyme should be aliquoted and stored at -80°C. Avoid repeated freeze-thaw cycles. The enzyme remains stable for at least 6 months when stored properly. Always keep the enzyme on ice when in use.

Human IMPDH, Type II (IMPDH2)

Name: Human IMPDH Type 2 (IMPDH2) Enzyme
Brand: NOVOCIB
SKU: IMPDH2-50U
Availability: InStock

Synonyms: inosine 5'-monophosphate dehydrogenase, type 2, IMP dehydrogenase, type II, IMPDH2.

Inosine 5'-monophosphate dehydrogenase type 2 (IMPDH 2, E.C.1.1.1.205) is the predominant isoform of IMPDH and a validated target to treat a wide range of cancers and infectious diseases and to prevent lymphocytes proliferation.

Catalytic activity
Inosine Monophosphate Dehydrogenase (IMPDH) converts inosine 5'-monophosphate (IMP) to xanthosine 5µ-monophosphate (XMP) using NAD+ as a cofactor.

The oxidation of IMP to XMP is considered as the pivotal step in the biosynthesis of guanine nucleotide, whose pool controls cell proliferation and many other major cellular processes(1). The decrease in guanine nucleotide resulting from IMPDH inhibition interrupts the nucleic acid synthesis in proliferating cells. The involvement of IMPDH in de novo guanine nucleotide biosynthesis makes IMPDH a crucial enzyme in cell proliferation and differentiation(2). IMPDH is recognized as a validated target for several major therapeutic areas. IMPDH inhibitors are exploited as antiviral (e.g. ribavirine), antiparasitic, antimicrobial, antileukemic, and immunosuppressive agents(2). IMPDH Type II is the predominant isoform of the enzyme and is selectively expressed in proliferating cells, including lymphocytes and tumor cells(2).

NOVOCIB's IMPDH 2 has been cloned by RT-PCR amplification of mRNA extracted from human hepatoma cells (NP_000875.2, 100% identity) and expressed in E.coli.

NOVOCIB's purified IMPDH 2 is an active enzyme characterized for its affinity for inosine 5'-monophosphate and NAD substrates, and its sensitivity to enzyme inhibitors such as mycophenolic acid and ribavirine-monophosphate.

Unit Definition: One unit of IMPDH Type II catalyzes the oxydation of 1 µmole of IMP to XMP per minute at pH 8.8 at 37 µC.

High Specific Activity: > 200 mU/mg protein.

Human IMPDH Type 2

Ref. #E-Nov1

#REF	SIZE	PRICE
#E-Nov1-100	Human IMPDH Type 2 100mU	295.00 €	295.00 € Inquiry
#E-Nov1-250	Human IMPDH Type 2 250mU	550.00 €	550.00 € Inquiry
#Screening E-Nov1	Human Recombinant IMPDH2 Screening Service IC50 determination for new compounds, performed in duplicate, with mycophenolic acid as the positive control.	590.00 €	590.00 € Inquiry

Last updated on : December 8th, 2025.

You can ask us for a quotation here or write at contact@novocib.com

Download our brochure "NovoCIB's IMPDH Products & Services"

Assay condition: KH2PO4 0.1M, pH8.8, NAD 250µM, DTT 2.5mM, 2.5mU/ml of human recombinant IMPDH II, Incubation at 37µC. Reaction started by adding IMP at 250µM final concentration. NADH formation was followed in an iEMS Reader MF (Labsystems) plate reader at 340nm.

SDS-PAGE analysis of purified Human IMPDH Type 2 showing high purity

IMPDH II inhibition by MPA

Dose-response curve showing IMPDH Type 2 inhibition by mycophenolic acid

Download this Document: "NOVOCIB's Human Recombinant IMPDH"

Download this Document: "NOVOCIB - IMPDH Products & Services"

How to measure the activity of IMPDH 2

Resuspend the content of the tube with lyophilized IMPDH type 2 (50–100 mU) in 200 µL of deionized water.
Prepare fresh reaction buffer: 1 mL of 50 mM KH₂PO₄ pH 8.5, 5 mM DTT*, 1 mM IMP*, 36°C.
Add 20 µL of IMPDH (or 10 µL for 100 µL) per 1 mL of buffer without NAD*.
Add 200 µL of this mixture to 4 wells and preincubate at 36°C for 10 min.
To start the reaction, add 5 µL of 40 mM NAD (1 mM final concentration) to 2 wells, leaving 2 others as a blank.
Follow the reaction at 340 nm and 25–36°C.

*For best results, always use freshly prepared solutions of DTT, IMP, and NAD.

Absorbance at 340 nm (200 µL per well, Corning® 3797 microplate)

Time (min)	IMP 1 mM, no NAD	IMP 1 mM, no NAD (duplicate)	IMP 1 mM + 1 mM NAD	IMP 1 mM + 1 mM NAD (duplicate)
0	0.118	0.116	0.167	0.165
1	0.118	0.116	0.205	0.203
2	0.119	0.117	0.244	0.240
3	0.120	0.116	0.283	0.278
4	0.121	0.116	0.322	0.316
5	0.121	0.116	0.362	0.354
6	0.121	0.116	0.401	0.392
7	0.122	0.116	0.440	0.430

Calculated Slopes (AU/min)

IMP 1 mM, no NAD: 0.0006
IMP 1 mM, no NAD (duplicate): 0
IMP 1 mM + 1 mM NAD: 0.0391
IMP 1 mM + 1 mM NAD (duplicate): 0.0378

Slope Mean (AU/min)

IMP 1 mM, no NAD: 0.0003
IMP 1 mM + 1 mM NAD: 0.0385

Slope After Blank Subtraction

AU/min: 0.0382

Enzyme Activity Calculations

Activity in well (U/mL): 0.00796
(divide AU/min by 4.8 which corresponds to absorbance of 1mM NADH in 200µL well of Corning® 3797 microplate)
Dilution factor (20 µL per 1 mL): ×50
Activity of enzyme solution (U/mL): 0.398
Amount of enzyme per tube (Units): 0.080

Kinetics of NADH Formation

IMPDH - A Key Target for Therapeutic Applications

Key Features:

High-purity human recombinant IMPDH Type 2
Fully characterized enzyme activity
Validated for inhibitor screening
Suitable for cancer and immunology research

Identify IMPDH2 inhibitors using NOVOCIB’s IMPDH type 2 or PRECISE IMPDH2 assay kit.
Compare against known inhibitors like MPA or ribavirin.
Confirm GTP depletion in inhibitor-treated cells using NOVOCIB’s Cellular Nucleotide Profiling (HPLC-UV).

Cellular Nucleotides Analysis

To validate IMPDH2 inhibitors identified in vitro, try our analytical service that measures guanine nucleotide depletion and related metabolic changes. These assays confirm whether compounds active in biochemical screens also suppress nucleotide synthesis in living cells.

Quantifies >30 ribo- and deoxyribonucleotides (mono-, di-, triphosphates) in a single run.
Used to measure depletion of GTP pools in cells treated with IMPDH inhibitors.
Validated reference inhibitors include mycophenolic acid (MPA), hydroxyurea (HU), methotrexate (MTX), and ribavirin.

Therapeutic Applications of IMPDH2

IMPDH in Immunology and Autoimmune Diseases

IMPDH plays a critical role in lymphocyte proliferation and immune response modulation, making it a prime target for:

Immunosuppressive Therapies: CellCept® (mycophenolate mofetil), a prodrug of mycophenolic acid, is a well-established IMPDH inhibitor used in organ transplantation and autoimmune conditions.
Autoimmune Disease Management: IMPDH inhibitors show significant promise in treating various autoimmune disorders including:

• Systemic Lupus Erythematosus (SLE)
• Rheumatoid Arthritis (RA)
• Psoriasis
• Myasthenia Gravis
• Lupus Nephritis

IMPDH in Oncology and Cancer Research

IMPDH Type 2 is overexpressed in many cancer cells, making it an attractive target for anticancer therapies:

Key Cancer Targets

Acute Myelogenous Leukemia (AML)
Chronic Myelogenous Leukemia (CML)
Pancreatic cancer
Colorectal cancer
Bladder cancer

Therapeutic Advantages

Overcomes drug resistance in cancer cells
Enhances efficacy of other anticancer drugs
Targets rapidly dividing cancer cells

Current IMPDH Inhibitors in Development

Approved Drugs

CellCept® (mycophenolate mofetil)
Ribavirin (antiviral)
Mizoribine (immunosuppressant)
Tiazofurine (antineoplastic)

Promising Candidates

AVN-944 - In trials for hematologic malignancies and solid tumors
Benzamide riboside - Phase II/III for leukemia
Novel small molecules - Multiple candidates in preclinical development

The continued elucidation of IMPDH's atomic structure and mechanism of action continues to drive the development of more potent and selective inhibitors, opening new possibilities for targeted therapies across multiple disease areas.

Frequently Asked Questions

Find answers to common questions about our analytical services

pH8.0-8.5

37°C

potassium (>20mM) and thiols (1-5mM DTT)

340nm

no, redox dyes will be non specifically reduce by DTT required for IMPDH activity

Have more questions? Our team is here to help.

Active Human IMPDH Type 2 Enzyme