Ekaterina Igorevna Gulk

@spbu.ru

Faculty of Biology, Department of plant Physiology and biochemistry
St. Petersburg State University

Ekaterina Igorevna Gulk


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https://researchid.co/ekaterinagulk

RESEARCH, TEACHING, or OTHER INTERESTS

Biochemistry, Physiology, Plant Science
3

Scopus Publications

Scopus Publications

  • Non-proteinogenic amino acids from marine macroalgae: diversity, functional roles, and biological activity
    Elena Tarakhovskaya, Ekaterina Gulk, Elizaveta Zamyatkina
    Phycologia, 2025
    A detailed understanding of the biochemical composition of seaweed is currently of great importance, since these organisms are becoming increasingly popular as food products and their specific metabolites exhibit diverse biological activities. This review summarizes the data on non-proteinogenic amino acids (AAs) occurring in marine macroalgae. We consider the molecular profiles, content, metabolism, physiological functions, biological activities and potential applied relevance of six groups of these compounds: ureido AAs, β-alanine and its derivatives, proline-like secondary AAs, kainoids, AA betaines, and sulphur-containing AAs. Special emphasis is made on the comparison of representatives of different taxonomic groups of macroalgae in their ability to synthesize and accumulate specific non-proteinogenic AAs. Of particular interest in this regard are three orders of red algae (Ceramiales, Palmariales, and Gigartinales) that feature the broadest spectrum and the highest concentrations of these metabolites. Analysis of the available literature has shown that, to date, the main gaps in our knowledge of non-proteinogenic AAs from macroalgae concern the physiological functions of these compounds and, especially, their metabolic pathways in the algal cells.
  • Metabolic Adjustment of High Intertidal Alga Pelvetia canaliculata to the Tidal Cycle Includes Oscillations of Soluble Carbohydrates, Phlorotannins, and Citric Acid Content
    Renata Islamova, Nikolay Yanshin, Elizaveta Zamyatkina, Ekaterina Gulk, Ekaterina Zuy, Susan Billig, Claudia Birkemeyer, Elena Tarakhovskaya
    International Journal of Molecular Sciences, 2023
    The brown alga Pelvetia canaliculata is one of the species successfully adapted to intertidal conditions. Inhabiting the high intertidal zone, Pelvetia spends most of its life exposed to air, where it is subjected to desiccation, light, and temperature stresses. However, the physiological and biochemical mechanisms allowing this alga to tolerate such extreme conditions are still largely unknown. The objective of our study is to compare the biochemical composition of Pelvetia during the different phases of the tidal cycle. To our knowledge, this study is the first attempt to draft a detailed biochemical network underneath the complex physiological processes, conferring the successful survival of this organism in the harsh conditions of the high intertidal zone of the polar seas. We considered the tide-induced changes in relative water content, stress markers, titratable acidity, pigment, and phlorotannin content, as well as the low molecular weight metabolite profiles (GC-MS-based approach) in Pelvetia thalli. Thallus desiccation was not accompanied by considerable increase in reactive oxygen species content. Metabolic adjustment of P. canaliculata to emersion included accumulation of soluble carbohydrates, various phenolic compounds, including intracellular phlorotannins, and fatty acids. Changes in titratable acidity accompanied by the oscillations of citric acid content imply that some processes related to the crassulacean acid metabolism (CAM) may be involved in Pelvetia adaptation to the tidal cycle.
  • Biochemical Composition of Euglena gracilis Cells during Mixotrophic Growth in the Presence of Various Organic Substrates
    E. I. Gulk, E. B. Zamyatkina, C. Birkemeyer, E. R. Tarakhovskaya
    Russian Journal of Plant Physiology, 2023
    Abstract The general biochemical composition and profile of low molecular weight metabolites of euglena (Euglena gracilis Klebs.) cells grown in a mixotrophic culture supplemented with 0.5% ethanol, glucose, butanol, glycine, or glycerol was studied. Ethanol and glucose significantly stimulated the growth of the Euglena culture and the accumulation of storage compounds (paramylon and wax esters) in the cells. Butanol also contributed to the division of euglena cells and increased biosynthesis of protein, mono- and disaccharides, carotenoids, and tocopherols. Glycine and glycerol were metabolized more slowly than other substrates, and they accumulated in E. gracilis cells along with their direct derivatives. Glycine did not stimulate the growth of the culture, but it caused the accumulation of paramylon, organic acids of the Krebs cycle, and nitrogen-containing metabolites (chlorophyll, free amino acids, and nitrogenous bases) in the cells. Apparently, glycine is equally effectively used by Euglena as an additional source of both carbon and nitrogen under the conditions of mixotrophy. Assimilation of glycerol was accompanied by the accumulation of wax esters and the amino acids proline and ornithine in Euglena cells. In general, the results obtained demonstrate the ability of Euglena to significantly rearrange its metabolism during the assimilation of organic substrates of various chemical nature. Our data can be used in the context of E. gracilis practical applications.