NADP-malate dehydrogenase from Zea mays leaves: Amino acid composition and thiol content of active and inactive forms

C. L.D. Jenkins, L. E. Anderson, M. D. Hatch

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

NADP-malate dehydrogenase (L-malate: NADP+ oxidoreductase, E.C. 1.1.1.82) was purified from the leaves of Zea mays L. and its subunit molecular weight, amino acid composition and the changes in number of thiol groups during activation were determined. The amino acid composition we found differed from that reported earlier for the Z. mays enzyme but was very similar to that reported for the enzyme isolated from pea leaves. The maize enzyme contains fewer methionine residues (3 compared to 5 in pea) but a greater total number of cysteine residues (6 compared to 3 in pea). In its inactive form (oxidised) the enzyme contained 2 thiols per subunit of which only 1 reacts with 5,5′-dithiobis(2-nitrobenzoic acid) when the enzyme is in its native form. During activation by dithiothreitol two disulphide bonds are reduced per subunit to give 4 new thiol groups. We conclude that NADP-malate dehydrogenase from leaves of the C4 plant Z. mays is very similar to the enzyme from the C3 plant pea. However, apparently two disulphide bonds are reduced during the reductive activation of the Z. mays enzyme in vitro compared with 1 disulphide bond for the pea enzyme.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalPlant Science
Volume45
Issue number1
DOIs
Publication statusPublished - 1986
Externally publishedYes

Keywords

  • amino acid composition
  • enzyme activation
  • NADP-malate dehydrogenase
  • thiol content
  • Zea mays leaves

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