Stabilization Mechanism of Glucose-6-phosphate Dehydrogenase

نویسندگان

  • E. A. Zaitseva
  • E. S. Chukhrai
  • O. M. Poltorak
چکیده

Yeast glucose-6-phosphate dehydrogenase (G6PDH) in solutions exists as the equilibrium mixture of dimers and tetramers. Only dimers are active. The equation responding to these conditions was used to determine the parameters: the specific activity of dimers and the dissociation equilibrium constant of tetramers. The stability of G6PDH dimers were shown to be maintained due to the conformational lock, a multiple-point intersubunit contact in the hydrophobic region of “cylindrical” protomers. The conformational lock is formed by two isolated contacts at least. In the consecutive mechanism of G6PDH thermal inactivation, the destruction of one of these contacts results in a labile dimer. The latter dissociates to inactive monomers. At 46◦C, the equilibrium constant of this process K dis = (6.2± 0.4) nM, whereas the specific activity dimers a2 = (13 ± 0.2) × 10 mol NADPH/min.mol of active sites. The kinetic analysis showed that the inactivation process is preceded by tree steps: the dissociation of tetramers to active stable dimers, the emergence of labile dimers and their dissociation to inactive protomers. The final step of G6PDH thermal inactivation is an irreversible inactivation of protomers, the denaturation with the rate constant k = 6× 10−3 min−1 .

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

INHIBITION OF HUMAN ERYTHROCYTE GLUCOSE 6-PHOSPHATE DEHYDROGENASE ACTIVITY BY DEHYDROEPIANDROSTERONE AND RELATED STEROIDS.

The inhibitory effects of several steroids on G6PD activity using intact erythrocytes are reported. Incubation of whole blood with dehydroepiandrosterone (DHEA) resulted in 42% and 12% inhibition in the enzyme activity in the presence and absence of oxygen, respectively. Addition of epinephrine and/or aminophylline into the incubation medium caused further enzyme inhibition suggesting a po...

متن کامل

MOLECULAR IDENTIFICATION OF THE MOST PREVALENT MUTATION OF GLUCOSE-6-PHOSPHATE DEHYDROGENASE (G6PD) GENE IN DEFICIENT PATIENTS IN GILAN PROVINCE

Glucose-6-Phosphate Dehydrogenase (G6PD) is a cytosolic enzyme which its main function is to produce NADPH in the red blood cells by controlling the step from Glucose-6-Phosphate to 6-Phospho gluconate in the pentose phosphate pathway. G6PD deficiency is the most common X-chromosome linked hereditary enzymopathy in the world, that result in reduced enzyme activity and more than 125 different mu...

متن کامل

P-90: Effect of Phosphodiesterase Type3 Inhibitor, Cilostamide, on The Developmental Competence of Ovine OocytesIsolated by Glucose 6-Phosphate Dehydrogenase Activity

Background: The developmental competence of oocytes matured in vitro (IVM) is yet far below than in vivo counterparts. Recent studies suggest that the asynchrony between nuclear/cytoplasmic maturation and the initial low/heterogeneous quality of oocytes are the most important factors affecting IVM success. We investigated whether selection of growing oocytes (based on their glucose 6- phosphate...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2001