Record Details


Field	Value

Title	Inactivation of maize NADP-malic enzyme by Cu²⁺ -ascorbate

Creator	Pinto, S E Rao, S R Bhagwat, A S

Description	55-59 Maize malic enzyme was rapidly inactivated by micromolar concentrations of cupric nitrate in the presence of ascorbate at pH, 5.0. Ascorbate or Cu²⁺ alone had no effect on enzyme activity. The substrate L-malate or NADP individually provided almost total protection against Cu²⁺-ascorbate inactivation. The loss of enzyme activity was accompanied by cleavage of the enzyme. The cleaved peptides showed molecular mass of 55 kDa, 48 kDa, 38 kDa, and 14 kDa. Addition of EDTA, histidine and imidazole provided protection. The results of protection experiments with sodium azide, DABCO and catalase suggested that reactive oxygen species were generated resulting in loss of enzyme activity. This was further supported by experiments showing that the rate of enzyme inactivation was higher in D₂O than in water. It is suggested that maize malic enzyme is modified by reactive oxygen species like singlet oxygen and H₂O₂ generated by Cu²⁺- ascorbate system and the modified amino acid residue(s) may be located at or near the substrate-binding site of the enzyme.

Date	2013-07-15T06:12:52Z 2013-07-15T06:12:52Z 2002-02

Type	Article

Identifier	0975-0959 (Online); 0301-1208 (Print) http://hdl.handle.net/123456789/19748

Language	en_US

Rights	CC Attribution-Noncommercial-No Derivative Works 2.5 India

Publisher	NISCAIR-CSIR, India

Source	IJBB Vol.39(1) [February 2002]

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