Structure and function of the mitochondrial P450 system electron transfer proteins, adrenodoxin reductase and adrenodoxin

1992 ◽  
Vol 3 (Supplement) ◽  
Author(s):  
I. Hanukoglu ◽  
R. Rapoport ◽  
S. Schweiger ◽  
D. Sklan ◽  
L. Weiner ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Structure And Function ◽  
Electron Transfer Proteins ◽  
Adrenodoxin Reductase ◽  
And Function

scholarly journals Structure and function of Aspergillus niger laccase McoG

Biocatalysis ◽  
2017 ◽  
Vol 3 (1) ◽  
pp. 1-21 ◽  
Author(s):  
Marta Ferraroni ◽  
Adrie H. Westphal ◽  
Marco Borsari ◽  
Juan Antonio Tamayo-Ramos ◽  
Fabrizio Briganti ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Transfer ◽  
Aspergillus Niger ◽  
Structure And Function ◽  
Redox Potentials ◽  
Wild Type ◽  
Multicopper Oxidases ◽  
Transfer Rates ◽  
The Common ◽  
And Function

AbstractThe ascomycete Aspergillus niger produces several multicopper oxidases, but their biocatalytic properties remain largely unknown. Elucidation of the crystal structure of A. niger laccase McoG at 1.7 Å resolution revealed that the C-terminal tail of this glycoprotein blocks the T3 solvent channel and that a peroxide ion bridges the two T3 copper atoms. Remarkably, McoG contains a histidine (His253) instead of the common aspartate or glutamate expected to be involved in catalytic proton transfer with phenolic compounds. The crystal structure of H253D at 1.5 Å resolution resembles the wild type structure. McoG and the H253D, H253A and H253N variants have similar activities with 2,2’-azino-bis(3- ethylbenzothiazoline-6-sulphonic acid or N,N-dimethyl-p-phenylenediamine sulphate. However, the activities of H253A and H253N with 2-amino-4-methylphenol and 2-amino-4-methoxyphenol are strongly reduced compared to that of wild type. The redox potentials and electron transfer rates (k

scholarly journals Use of rosy mutant strains of Drosophila melanogaster to probe the structure and function of xanthine dehydrogenase

1992 ◽  
Vol 285 (2) ◽  
pp. 507-513 ◽  
Author(s):  
R K Hughes ◽  
W A Doyle ◽  
A Chovnick ◽  
J R S Whittle ◽  
J F Burke ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Drosophila Melanogaster ◽  
Biochemical Study ◽  
Structural Data ◽  
Xanthine Dehydrogenase ◽  
Structure And Function ◽  
Sequence Comparisons ◽  
Activity Data ◽  
Mutant Strains ◽  
And Function

The usefulness in structure/function studies of molybdenum-containing hydroxylases in work with rosy mutant strains of Drosophila melanogaster has been investigated. At least 23 such strains are available, each corresponding to a single known amino acid change in the xanthine dehydrogenase sequence. Sequence comparisons permit identification, with some certainty, of regions associated with the iron-sulphur centres and the pterin molybdenum cofactor of the enzyme. Procedures have been developed and rigorously tested for the assay in gel-filtered extracts of the flies, of different catalytic activities of xanthine dehydrogenase by the use of various oxidizing and reducing substrates. These methods have been applied to 11 different rosy mutant strains that map to different regions of the sequence. All the mutations studied cause characteristic activity changes in the enzyme. In general these are consistent with the accepted assignment of the cofactors to the different domains and with the known reactivities of the molybdenum, flavin and iron-sulphur centres. Most results are interpretable in terms of the mutation affecting electron transfer to or from one redox centre only. The activity data provide evidence that FAD and the NAD+/NADH binding sites are retained in mutants mapping to the flavin domain. Therefore, despite some indications from sequence comparisons, it is concluded that the structure of this domain of xanthine dehydrogenase cannot be directly related to that of other flavoproteins for which structural data are available. The data also indicate that the artificial electron acceptor phenazine methosulphate acts at the iron-sulphur centres and suggest that these centres may not be essential for electron transfer between molybdenum and flavin. The work emphasizes the importance of combined genetic and biochemical study of rosy mutant xanthine dehydrogenase variants in probing the structure and function of enzymes of this class.

Sign in / Sign up

Export Citation Format

Share Document