PAD4 (human, recombinant)

Protein arginine deiminase 4 (PAD4) catalyzes the conversion of arginine residues to citrulline within cellular protein substrates, resulting in the loss of a positive charge, which can alter protein structure and/or function.¹ It is expressed in neutrophils, as well as a variety of tissues, including the brain, liver, lung, and kidney.^1,2,3 PAD4 has a key role in NETosis, a lytic form of cell death characterized by the release of neutrophil extracellular traps (NETs).¹ Upon neutrophil activation, PAD4 translocates to the nucleus where it citrullinates histones, initiating chromatin decondensation and the release of NETs.^2,4,5 Neutrophils isolated from Pad4^-/- mice exhibit decreased citrullination of histone H3 under both basal and LPS-stimulated conditions and are defective for NET formation in response to stimulation with LPS, phorbol 12-myristate 13-acetate (PMA; Item No. 10008014), or hydrogen peroxide.⁴ Pad4^-/- mice exhibit larger lesions than wild-type mice in a model of necrotizing fasciitis induced by M1 group A S. pyogenes lacking the extracellular DNase Sda1. Pad4-deficient mice also exhibit reduced infarct size in a model of myocardial ischemia-reperfusion injury and reduced tumor growth in a Lewis lung carcinoma model.^6,2 PADI4 SNPs, including G55S, V82A, and G112A, are associated with rheumatoid arthritis in humans.⁷ Cayman’s PAD4 (human, recombinant) protein contains the G55S, V82A, and G112A SNPs and can be used for enzyme activity assays.

WARNING This product is not for human or veterinary use.

1. van Beers, J.J.B.C., Zendman, A.J.W., Raijmakers, R., et al. Peptidylarginine deiminase expression and activity in PAD2 knock-out and PAD4-low mice. Biochimie 95(2), 299-308 (2013).

2. Demers, M., Wong, S.L., Martinod, K., et al. Priming of neutrophils toward NETosis promotes tumor growth. Oncoimmunology 5(5), e1134073 (2016).

3. Jones, J.E., Causey, C.P., Knuckley, B., et al. Protein arginine deiminase 4 (PAD4): Current understanding and future therapeutic potential. Curr. Opin. Drug Discov. Devel. 12(5), 616-627 (2009).

4. Li, P., Li, M., Lindberg, M.R., et al. PAD4 is essential for antibacterial innate immunity mediated by neutrophil extracellular traps. J. Exp. Med. 207(9), 1853-1862 (2010).

5. Thiam, H.R., Wong, S.L., Qiu, R., et al. NETosis proceeds by cytoskeleton and endomembrane disassembly and PAD4-mediated chromatin decondensation and nuclear envelope rupture. Proc. Natl. Acad. Sci. USA 117(13), 7326-7337 (2020).

6. Savchenko, A.S., Borissoff, J.I., Martinod, K., et al. VWF-mediated leukocyte recruitment with chromatin decondensation by PAD4 increases myocardial ischemia/reperfusion injury in mice. Blood 123(1), 141-148 (2014).

7. Suzuki, A., Yamada, R., Chang, X., et al. Functional haplotypes of PADI4, encoding citrullinating enzyme peptidylarginine deiminase 4, are associated with rheumatoid arthritis. Nat. Genet. 34(4), 395-402 (2003).

Hintzen, J.C.J., Beckley, K.D., Goldberg, E.L., et al. Internally quenched fluorescent peptides provide insights into underexplored and reversible post-translational modifications. Chem. Sci. 17(4), 2317-2331 (2025).

Saunders, C., Rocha-Rangel, P., Desai, R., et al. Citrullination of TDP-43 is a key post-translation modification associated with structural and functional changes and progressive pathology in TDP-43 mouse models and human proteinopathies. BioRxiv [Preprint] (2025).

Martin, M., Nilsson, S.C., Eikrem, D., et al. Citrullination of C1-inhibitor as a mechanism of impaired complement regulation in rheumatoid arthritis. Front. Immunol. 14, 1203506 (2023).

Jentink, N., Purnell, C., Kable, B., et al. Cryoelectron tomography reveals the multiplex anatomy of condensed native chromatin and its unfolding by histone citrullination. Mol. Cell. 83(18), 3236-3252 (2023).

Martín Monreal, M.T., Hansen, B.E., Iversen, P.F., et al. Citrullination of myelin basic protein induces a Th17-cell response in healthy individuals and enhances the presentation of MBP85-99 in patients with multiple sclerosis. J. Autoimmun. 139, 103092 (2023).

Kangro, K., Campbell, R.A., Tilvawala, R., et al. Citrullination of α2-antiplasmin is unlikely to contribute to enhanced plasmin generation in COVID-19 pathophysiology. Res. Pract. Thromb. Haemost. 7(6), 102195 (2023).

Yao, H., Cao, G., Liu, Z., et al. Inhibition of netosis with PAD inhibitor attenuates endotoxin shock induced systemic inflammation. Int. J. Mol. Sci. 23(21), 13264 (2022).

Crestani, E., Harb, H., Charbonnier, L.M., et al. Untargeted metabolomic profiling identifies disease-specific signatures in food allergy and asthma. J. Allergy Clin. Immunol. 145(3), 897-906 (2020).

Monreal, M.T.M., Rebak, A.S., Massarenti, L., et al. Applicability of small-molecule inhibitors in the study of peptidyl arginine deiminase 2 (PAD2) and PAD4. Front. Immunol. 12, 716250 (2021).

Damiana, T., Damgaard, D., Sidelmann, J.J., et al. Citrullination of fibrinogen by peptidylarginine deiminase 2 impairs fibrin clot structure. Clin. Chim. Acta 501, 6-11 (2020).

Thålin, C., Aguilera, K., Hall, N.W., et al. Quantification of citrullinated histones: Development of an improved assay to reliably quantify nucleosomal H3Cit in human plasma. J. Thromb. Haemost. 18(10), 2732-2743 (2020).

Damgaard, D., Bawadekar, M., Senolt, L., et al. Relative efficiencies of peptidylarginine deiminase 2 and 4 in generating target sites for anti-citrullinated protein antibodies in fibrinogen, alpha-enolase and histone H3. PLoS One 13(8), e0203214 (2018).

Thålin, C., Daleskog, M., Göransson, S.P., et al. Validation of an enzyme-linked immunosorbent assay for the quantification of citrullinated histone H3 as a marker for neutrophil extracellular traps in human plasma. Immunol. Res. 65(3), 706-712 (2017).