Oxidation of parathyroid hormone

• Published in: Clinica chimica acta Vol. 506; pp. 84 - 91
• Main Authors: Ursem, Stan R., Vervloet, Marc G., de Jongh, Renate T., Heijboer, Annemieke C.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.07.2020
• Subjects: Animals; Bio-active PTH; CKD; Humans; Immunoassay; Non-oxidized PTH; Oxidation-Reduction; Parathyroid hormone; Parathyroid Hormone - metabolism; PTH-analogues; Immunoassay; CaSR; Non-oxidized PTH; ox(Met8)PTH; ox(Met8,18)PTH; PTH; tPTH; ox(Met18)PTH; oxPTH; PTH1R; cAMP; Bio-active PTH; RP-HPLC; PTH-analogues; Parathyroid hormone; n-oxPTH; CKD; Met
• ISSN: 0009-8981; 1873-3492
• DOI: 10.1016/j.cca.2020.03.020

•The two methionine amino acids in parathyroid hormone are prone to oxidation.•This oxidation happens in vivo and decreases the biological activity.•We can currently separate and measure only non-oxidized PTH (n-oxPTH).•Future clinical studies need to further corroborate the added value of n-oxPTH. Parathyroid hormone (PTH) is the key hormone regulating calcium homeostasis and, as such, is an important diagnostic and prognostic marker. Although the measurement of PTH has greatly improved over the past few decades, oxidation status thereof is unaccounted for in currently used assays. PTH can be oxidized on methionine residues located at amino acid positions 8 and 18. This is a relevant post-translational modification as, due to refolding of the molecule, it results in the decreased ability to activate the PTH1 receptor. Although this loss of activity after oxidation was observed as early as 1934, only recently a method was developed to measure and distinguish non-oxidized PTH (n-oxPTH) from oxidized PTH. This method creates exciting possibilities for studying more specifically the role of n-oxPTH in physiology and pathology. Therefore, it can now be explored what the clinical implications of measuring n-oxPTH will be. Herein, we review the available evidence of the effect of oxidation on the biological activity of PTH. We also discuss studies examining the mechanism of PTH oxidation in vivo and efforts to stabilize synthetic PTH ex vivo for therapeutic applications. Lastly, the available studies regarding the clinical significance of n-oxPTH are evaluated and future directions discussed.