Photo-Oxidation of Therapeutic Protein Formulations: From Radical Formation to Analytical Techniques

Abstract

UV and ambient light-induced modifications and related degradation of therapeutic proteins are observed during manufacturing and storage. Therefore, to ensure product quality, protein formulations need to be analyzed with respect to photo-degradation processes and eventually protected from light exposure. This task usually demands the application and combination of various analytical methods. This review addresses analytical aspects of investigating photo-oxidation products and related mediators such as reactive oxygen species generated via UV and ambient light with well-established and novel techniques.

Copper-histidine therapy in an infant with novel splice-site variant in theATP7Agene of Menkes disease: the first experience in South East Asia and literature review

“…In an oxygen-enrich environment, histidine photooxidation mainly occurs via the type II mechanism. In this mechanism, the energy from light is transferred to the ground state oxygen molecule which turns into a singlet oxygen ( 1 O 2 ) 38. The singlet oxygen is unstable endoperoxide and in turn, reacts with imidazole residue of histidine, which further degrades to aspartic acid, urea and asparagine derivatives via several intermediate compounds 37 39.…”

Protein photodegradation in the visible range? Insights into protein photooxidation with respect to protein concentration

“…The formed species may be singlet oxygen ( 1 O 2 ), superoxide anion (O 2 − •), hydroxyl radicals (OH•) or different organic radicals (R•). All these species combined will be termed as “reactive species”, because the reaction with nitroxide radicals will cause a loss of paramagnetism by one electron reduction or one electron oxidation resulting in the formation of hydroxylamines and oxo-ammonium cations, respectively ( Hipper et al, 2021 ; Polovka et al, 2003 ).…”

Histidine Photooxygenation Chemistry: Mechanistic Evidence and Elucidation

“…Given the ambiguity of the reaction mechanism for the type I process arising from variations in generated reactive oxygen species and involvement of radical chain reactions that make the identification and characterization of specific products more challenging, [8] this review places its primary emphasis on histidine photooxygenation mediated by the type II mechanism.…”

“…In both pathways, excited singlet states of photosensitizers ( 1 PS*), achieved upon light irradiation, undergo transitioning to triplet excited states ( 3 PS*) via intersystem crossing (ISC). [8,9] In the type I pathway, 3 PS* transfers one electron to a target substrate, resulting in the formation of radicals and radical ions. These species then react with molecular oxygen, giving rise to the generation of highly reactive oxygen species such as superoxide anions and hydroxy radicals.…”

“…As a consequence, a diverse array of oxidation products and mechanisms arises, presenting challenges in their interpretation. Although previously disclosed review articles addressing the photooxygenation-induced degradation of amino acids and proteins have focused on the transformation of methionine, cysteine, tryptophan, tyrosine, and histidine, [7,8] there is a noticeable gap in literature regarding a comprehensive investigation of intermediate structures, as well as the impact of pH on the reaction pathway and resulting products, specifically in the context of histidine photooxygenation. This review aims to deliver a thorough overview of histidine photooxygenation chemistry, encompassing a comprehensive analysis of products, mechanisms involved in their formation, and analytical techniques that directly led to their identification.…”