Abstract
The kinetic mechanism of NADPH-dependent aldehyde reductase II and aldose reductase, purified from human placenta, has been studied using l-glucuronate and dl-glyceraldehyde as their respective substrates. For aldehyde reductase II, the initial velocity and product inhibition studies (using NADP and gulonate) indicate that the enzyme reaction sequence is ordered with NADPH binding to the free enzyme and NADP being the last product to be released. Inhibition patterns using menadione (an analog of the aldehydic substrate) and ATP-ribose (an analog of NADPH) are also consistent with a compulsory ordered reaction sequence. Isotope effects of deuteriumsubstituted NADPH (NADPD) also corroborate the above reaction scheme and indicate that hydride transfer is not the sole rate-limiting step in the reaction sequence. For aldose reductase, initial velocity patterns, product, and dead-end inhibition studies indicate a random binding pattern of the substrates and an ordered release of product; the coenzyme is released last. A steady-state random mechanism is also consistent with deuterium isotope effects of NADPD on the reaction sequence catalyzed by this enzyme. However, the hydride transfer step seems to be more rate determining for aldose reductase than for aldehyde reductase II.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 264-274 |
| Number of pages | 11 |
| Journal | Archives of Biochemistry and Biophysics |
| Volume | 261 |
| Issue number | 2 |
| DOIs | |
| State | Published - 1988 |
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ASJC Scopus subject areas
- Biochemistry
- Biophysics
- Molecular Biology
Cite this
The kinetic mechanism of human placental aldose reductase and aldehyde reductase II. / Bhatnagar, Aruni; Das, Ballabh; Gavva, Sandhya R.; Cook, Paul F.; Srivastava, Satish.
In: Archives of Biochemistry and Biophysics, Vol. 261, No. 2, 1988, p. 264-274.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The kinetic mechanism of human placental aldose reductase and aldehyde reductase II
AU - Bhatnagar, Aruni
AU - Das, Ballabh
AU - Gavva, Sandhya R.
AU - Cook, Paul F.
AU - Srivastava, Satish
PY - 1988
Y1 - 1988
N2 - The kinetic mechanism of NADPH-dependent aldehyde reductase II and aldose reductase, purified from human placenta, has been studied using l-glucuronate and dl-glyceraldehyde as their respective substrates. For aldehyde reductase II, the initial velocity and product inhibition studies (using NADP and gulonate) indicate that the enzyme reaction sequence is ordered with NADPH binding to the free enzyme and NADP being the last product to be released. Inhibition patterns using menadione (an analog of the aldehydic substrate) and ATP-ribose (an analog of NADPH) are also consistent with a compulsory ordered reaction sequence. Isotope effects of deuteriumsubstituted NADPH (NADPD) also corroborate the above reaction scheme and indicate that hydride transfer is not the sole rate-limiting step in the reaction sequence. For aldose reductase, initial velocity patterns, product, and dead-end inhibition studies indicate a random binding pattern of the substrates and an ordered release of product; the coenzyme is released last. A steady-state random mechanism is also consistent with deuterium isotope effects of NADPD on the reaction sequence catalyzed by this enzyme. However, the hydride transfer step seems to be more rate determining for aldose reductase than for aldehyde reductase II.
AB - The kinetic mechanism of NADPH-dependent aldehyde reductase II and aldose reductase, purified from human placenta, has been studied using l-glucuronate and dl-glyceraldehyde as their respective substrates. For aldehyde reductase II, the initial velocity and product inhibition studies (using NADP and gulonate) indicate that the enzyme reaction sequence is ordered with NADPH binding to the free enzyme and NADP being the last product to be released. Inhibition patterns using menadione (an analog of the aldehydic substrate) and ATP-ribose (an analog of NADPH) are also consistent with a compulsory ordered reaction sequence. Isotope effects of deuteriumsubstituted NADPH (NADPD) also corroborate the above reaction scheme and indicate that hydride transfer is not the sole rate-limiting step in the reaction sequence. For aldose reductase, initial velocity patterns, product, and dead-end inhibition studies indicate a random binding pattern of the substrates and an ordered release of product; the coenzyme is released last. A steady-state random mechanism is also consistent with deuterium isotope effects of NADPD on the reaction sequence catalyzed by this enzyme. However, the hydride transfer step seems to be more rate determining for aldose reductase than for aldehyde reductase II.
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U2 - 10.1016/0003-9861(88)90341-4
DO - 10.1016/0003-9861(88)90341-4
M3 - Article
VL - 261
SP - 264
EP - 274
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
SN - 0003-9861
IS - 2
ER -