ISSN:
1075-4261
Keywords:
protein structure
;
cytochrome b5 reductase
;
recombinant mutant
;
FTIR
;
ferredoxin-NADP+ reductase
;
thermal denaturation
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Physics
Notes:
Fourier-transform infrared (FTIR) spectroscopy was used to study the change of protein structure of NADH-cytochrome b5 reductase in a soluble form. Recombinant mutant cytochrome b5 reductases, serine 127 to proline (S127P), and alanine (S127A) were investigated, where the mutation on Ser-127 to proline is a case found in patients of type II methemoglobinemia. The secondary structure of cytochrome b5 reductase was revealed tentatively by FTIR using resolution enhancement and band-fitting techniques, providing the contents of α-helix (22%), β-sheet (30%), random coil (27%), and β-turn (22%) for the wild-type cytochrome b5 reductase. The mutant enzyme, S127P, was more sensitive to the thermal denaturation than the wild type with increasing β-sheet structures observed at 1624 and 1672 cm-1 during the heat treatment and relatively decreasing in intensities of bands around 1640-1660 cm-1 during heat treatment. The secondary structure of ferredoxin-NADP+ reductase, one of the same family as cytochrome b5 reductase, predicted from FTIR data was similar to that of the wild-type cytochrome b5 reductase but significantly different in the content of β-sheet and was consistent with the X-ray crystallographic data of ferredoxin-NADP+ reductase. The mutation on Ser-127 to proline or alanine in cytochrome b5 reductase caused only a small change (3 or 9%, respectively) in total of α-helix, random coil, and β-turn contents and almost no change in the β-sheet content. These results suggest that the lability of the mutated cytochrome b5 reductases might not result simply from the secondary structural change but from possibly the tertiary structural change, including the peptide side chain positional and the protein-protein interactional changes. © 1997 John Wiley & Sons, Inc. Biospect 3: 215-223, 1997
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
Permalink
