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Stages of the formation of nonequivalence of active centers of transketolase from baker’s yeastстатья
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 6 марта 2019 г.
- Авторы: Solovjeva Olga N., Selivanov Vitaly A., Orlov Victor N., Kochetov German A.
- Журнал: MOLECULAR CATALYSIS
- Том: 466
- Год издания: 2019
- Первая страница: 122
- Последняя страница: 129
- DOI: 10.1016/j.mcat.2019.01.008
- Аннотация: For baker’s yeast transketolase (TK), cooperative binding of thiamine diphosphate (ThDP) and substrates in transferase reaction are known. We show here, that the differences in the properties of the active centers of TK are formed already with Ca2+ binding in one of the two initially identical subunits. When Ca2+ is bound only in one of the two active centers, the affinity of it to the second one decreases. The absence of cation in the second active center reduces the affinity of ThDP to the first active center. The binding of Ca2+ increases the thermal stability of apo- and holoTK, i.e. it changes the whole structure of the enzyme. Only in the presence of Ca2+, but not Mg2+, does the thermal stability of holoTK increase. In one-substrate reaction in the presence of Ca2+ it is observed a negative cooperativity in binding of xylulose-5-phosphate and hydroxypyruvate. For both substrates, Vmax of the first active center of holoTK, when it alone binds the substrate, is higher than of semiholoTK. When the substrate begins to bind also in the second active center, Vmax of the first active center decreases, which is explained by the previously shown flip-flop mechanism.
- Добавил в систему: Соловьева Ольга Николаевна