Effect of Cadmium, Mercury and Copper on Partially Purified Hepatic Flavokinase of Rat
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
View Archive Info| Field | Value | |
| Title |
Effect of Cadmium, Mercury and Copper on
Partially Purified Hepatic Flavokinase of Rat
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| Creator |
Bandyopadhyay, Debashis
Chatterjee, Ajay K Datta, Asoke G |
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| Subject |
Chemistry
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| Description |
The effect of cadmium (Cd2+), mercury (Hg2+) and copper (Cu2+) was studied with partially purified flavokinase (ATP:riboflavin
5¢-phosphotransferase EC 2.7.1.26) from rat liver. All the divalent heavy metal cations inhibited flavokinase activity in a concentration-
dependent manner. The inhibitory effect of cadmium on the enzyme was completely reversed by increasing concentration,
of Zinc (Zn2+) indicating a competition between Zn2+ and Cd2+ for binding with the enzyme. A competition between riboflavin
and Cd2+ is also evident from the present investigation. These observations hint at the possibility that Zn2+ and Cd2+ probably
compete for the same site on the enzyme where riboflavin binds. However, inhibition of flavokinase by Hg2+ could not be reversed
by Zn2+. Our studies further reveal that hepatic flavokinase appears to contain an essential, accessible and functional
thiol group(s) which is evident from a concentration dependent inhibition of activity by sulfhydryl reagents like parachloromercuribenzoate
(PCMB), 5,5¢-dithiobis (2-nitrobenzoic acid) (DTNB), and N-ethylmaleimide (NEM). Inhibition of flavokinase
by sulfhydryl reagents were protected, except in case of NEM inhibition, when the enzyme was incubated with thiol protectors
like glutathione (GSH) and dithiothreitol (DTT). Furthermore, the enzyme could also be protected from the inhibitory effect of
Cd2+ and Hg2+ by GSH and DTT suggesting that Cd2+ probably interacts with a reactive thiol group at or near the active site of
enzyme in bringing about its inhibitory effect.
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| Date |
1997
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| Type |
Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/807/1/MOLECULAR_AND_CELLULAR_BIOCHEMISTRY%2C_167(_1%2D2)%2C_73%2D80[85].pdf
Bandyopadhyay, Debashis and Chatterjee, Ajay K and Datta, Asoke G (1997) Effect of Cadmium, Mercury and Copper on Partially Purified Hepatic Flavokinase of Rat. Molecular and Cellular Biochemistry, 167. pp. 73-80. |
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| Relation |
http://dx.doi.org/10.1023/A:1018316531658
http://www.eprints.iicb.res.in/807/ |
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