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<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ali="http://www.niso.org/schemas/ali/1.0/" article-type="research-article" dtd-version="1.2" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">Acta Naturae</journal-id><journal-title-group><journal-title xml:lang="en">Acta Naturae</journal-title><trans-title-group xml:lang="ru"><trans-title>Acta Naturae</trans-title></trans-title-group></journal-title-group><issn publication-format="print">2075-8251</issn><publisher><publisher-name xml:lang="en">Acta Naturae Ltd</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="publisher-id">27820</article-id><article-id pub-id-type="doi">10.32607/actanaturae.27820</article-id><article-categories><subj-group subj-group-type="toc-heading" xml:lang="en"><subject>Research Articles</subject></subj-group><subj-group subj-group-type="toc-heading" xml:lang="ru"><subject>Экспериментальные статьи</subject></subj-group><subj-group subj-group-type="article-type"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title xml:lang="en">Stabilization of transaminases in aqueous-organic media by pyridoxal-5’-phosphate: a case study of transaminase from <italic>Desulfomonile tiedjei</italic></article-title><trans-title-group xml:lang="ru"><trans-title>Стабилизация трансаминаз в водно-органических средах пиридоксаль-5’-фосфатом на примере трансаминазы из <italic>Desulfomonile tiedjei</italic></trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Rudina</surname><given-names>I. V.</given-names></name><name xml:lang="ru"><surname>Рудина</surname><given-names>Ю. В.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>A.N. Bach Institute of Biochemistry</p></bio><bio xml:lang="ru"><p>Институт биохимии имени А.Н. Баха</p></bio><email>eubez@inbi.ras.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Bakunova</surname><given-names>A. K.</given-names></name><name xml:lang="ru"><surname>Бакунова</surname><given-names>А. К.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>A.N. Bach Institute of Biochemistry</p></bio><bio xml:lang="ru"><p>Институт биохимии имени А.Н. Баха</p></bio><email>eubez@inbi.ras.ru</email><xref ref-type="aff" rid="aff1"/></contrib><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Popov</surname><given-names>V. O.</given-names></name><name xml:lang="ru"><surname>Попов</surname><given-names>В. О.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>A.N. Bach Institute of Biochemistry; Department of Biology</p></bio><bio xml:lang="ru"><p>Институт биохимии имени А.Н. Баха; биологический факультет</p></bio><email>eubez@inbi.ras.ru</email><xref ref-type="aff" rid="aff1"/><xref ref-type="aff" rid="aff2"/></contrib><contrib contrib-type="author"><name-alternatives><name xml:lang="en"><surname>Bezsudnova</surname><given-names>E. Yu.</given-names></name><name xml:lang="ru"><surname>Безсуднова</surname><given-names>Е. Ю.</given-names></name></name-alternatives><address><country country="RU">Russian Federation</country></address><bio xml:lang="en"><p>A.N. Bach Institute of Biochemistry</p></bio><bio xml:lang="ru"><p>Институт биохимии имени А.Н. Баха</p></bio><email>eubez@inbi.ras.ru</email><xref ref-type="aff" rid="aff1"/></contrib></contrib-group><aff-alternatives id="aff1"><aff><institution xml:lang="en">Research Center of Biotechnology of the Russian Academy of Sciences</institution></aff><aff><institution xml:lang="ru">Федеральный исследовательский центр «Фундаментальные основы биотехнологии» Российской академии наук</institution></aff></aff-alternatives><aff-alternatives id="aff2"><aff><institution xml:lang="en">M. V. Lomonosov Moscow State University</institution></aff><aff><institution xml:lang="ru">Московский государственный университет имени М.В. Ломоносова</institution></aff></aff-alternatives><pub-date date-type="pub" iso-8601-date="2026-04-22" publication-format="electronic"><day>22</day><month>04</month><year>2026</year></pub-date><volume>18</volume><issue>1</issue><issue-title xml:lang="en"/><issue-title xml:lang="ru"/><fpage>83</fpage><lpage>90</lpage><history><date date-type="received" iso-8601-date="2025-09-16"><day>16</day><month>09</month><year>2025</year></date><date date-type="accepted" iso-8601-date="2026-01-28"><day>28</day><month>01</month><year>2026</year></date></history><permissions><copyright-statement xml:lang="en">Copyright ©; 2026, Rudina I.V., Bakunova A.K., Popov V.O., Bezsudnova E.Y.</copyright-statement><copyright-statement xml:lang="ru">Copyright ©; 2026, Рудина Ю.В., Бакунова А.К., Попов В.О., Безсуднова Е.Ю.</copyright-statement><copyright-year>2026</copyright-year><copyright-holder xml:lang="en">Rudina I.V., Bakunova A.K., Popov V.O., Bezsudnova E.Y.</copyright-holder><copyright-holder xml:lang="ru">Рудина Ю.В., Бакунова А.К., Попов В.О., Безсуднова Е.Ю.</copyright-holder><ali:free_to_read xmlns:ali="http://www.niso.org/schemas/ali/1.0/"/><license><ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">https://creativecommons.org/licenses/by/4.0</ali:license_ref></license></permissions><self-uri xlink:href="https://actanaturae.ru/2075-8251/article/view/27820">https://actanaturae.ru/2075-8251/article/view/27820</self-uri><abstract xml:lang="en"><p>Pyridoxal-5’-phosphate (PLP)-dependent transaminases are highly efficient biocatalysts for the stereoselective synthesis of chiral amines, which are key building blocks in pharmaceuticals and chemical manufacturing. Fundamental research on enzymatic transamination includes the classical works of Alexander Braunstein, who discovered the transamination reaction; David Metzler, who studied the spectral properties of PLP-dependent enzymes; Esmond Snell, who investigated the kinetics of PLP-dependent enzymes; as well as studies by other Russian and international researchers. Despite extensive studies on PLP-dependent transaminases, their practical application remains limited. In addition to the unfavorable equilibrium of the transamination reaction and the narrow substrate specificity of transaminases, their stability under manufacturing conditions is a major constraint. Transaminase stability encompasses not only the structural integrity of the protein globule, but also the enzyme’s ability to retain the PLP cofactor. PLP dissociation leads to enzyme inactivation and termination of the reaction. Modern biocatalytic processes are predominantly designed for aqueous–organic media to increase the solubility of hydrophobic substrates to hundreds of grams per liter. Under these conditions, the stability of transaminases, as with other enzymes, decreases. In the context of these challenges, this work investigates the efficiency of PLP binding as a factor in stabilizing the active holoenzyme of the transaminase from <italic>Desulfomonile tiedjei</italic> in various aqueous–organic media. The study analyzes the transaminase stability and catalytic activity in the presence of methanol, DMSO, and Cyrene (up to 20% <italic>v</italic>/<italic>v</italic>), both in incubation mode and under reaction conditions. Particular attention is paid to the analysis of the effect of the amino acid substitution T199Q in the cofactor-binding region on the enzyme’s resistance to organic solvents. The present study contributes to addressing the practical problem of stabilizing transaminases in aqueous–organic media. The results also deepen our understanding of the molecular basis of the stability of PLP-dependent enzymes.</p></abstract><trans-abstract xml:lang="ru"><p>Пиридоксаль-5’-фосфат (PLP)-зависимые трансаминазы являются высокоэффективными биокатализаторами стереоселективного синтеза хиральных аминов – ключевых «строительных блоков» в фармацевтическом и химическом производствах. Фундаментальные исследования ферментативного трансаминирования включают классические работы Александра Браунштейна, открывшего реакцию переаминирования, Дэвида Метцлера, исследовавшего спектральные свойства пиридоксалевых ферментов, Эсмонда Снелла, изучавшего кинетику PLP-зависимых ферментов, и других российских и зарубежных ученых. Практическое применение PLP-зависимых трансаминаз ограничивается не только неблагоприятным равновесием реакции трансаминирования и узкой субстратной специфичностью, но и стабильностью трансаминаз в технологических условиях. Стабильность трансаминаз – это не только стабильность белковой глобулы, но и способность трансаминаз удерживать кофактор PLP, диссоциация которого приводит к инактивации фермента и остановке синтеза. Современные биокаталитические процессы разрабатываются преимущественно для водно-органических сред, чтобы повысить растворимость гидрофобных субстратов до концентраций в сотни г/л. В этих условиях стабильность трансаминаз, как и других ферментов, снижается. В контексте этих задач нами изучена эффективность связывания PLP в активном центре как фактора стабилизации холофермента трансаминазы из<italic> Desulfomonile tiedjei</italic> в разных водно-органических средах. Проанализирована стабильность и каталитическая активность трансаминазы в присутствии метанола, диметилсульфоксида и цирена (до 20% <italic>v</italic>/<italic>v</italic>) как в режиме инкубации, так и в реакционных условиях. Особое внимание уделено анализу влияния аминокислотной замены T199Q в области связывания кофактора на устойчивость фермента к действию органических растворителей. Проведенные исследования вносят вклад в решение прикладной задачи стабилизации трансаминаз в водно-органических средах. Полученные результаты углубляют понимание молекулярных основ стабильности PLP-зависимых ферментов.</p></trans-abstract><kwd-group xml:lang="en"><kwd>transaminases</kwd><kwd>enzyme catalysis</kwd><kwd>stability</kwd><kwd>organic solvents</kwd></kwd-group><kwd-group xml:lang="ru"><kwd>трансаминазы</kwd><kwd>ферментативный катализ</kwd><kwd>стабильность</kwd><kwd>органические растворители</kwd></kwd-group><funding-group><award-group><funding-source><institution-wrap><institution xml:lang="en">Russian Science Foundation</institution></institution-wrap><institution-wrap><institution xml:lang="ru">Российский научный фонд</institution></institution-wrap></funding-source><award-id>23-74-30004</award-id></award-group><funding-statement xml:lang="en">This work was supported by the Russian Science Foundation (project No. 23-74-30004).</funding-statement><funding-statement xml:lang="ru">Работа поддержана Российским научным фондом, грант № 23-74-30004.</funding-statement></funding-group></article-meta></front><body></body><back><ref-list><ref id="B1"><label>1.</label><mixed-citation>Eliot AC, Kirsch JF. 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