Electron paramagnetic resonance studies of ferric cytochrome c′ from photosynthetic bacteria

Fujii, Satoshi; Yoshimura, Tetsuhiko; Kamada, Hitoshi; Yamaguchi, Kazuya; Suzuki, Shinnichiro; Shidara, Sohsuke; Takakuwa, Soemon

doi:10.1016/0167-4838(95)00092-9

Cited by 46 publications

(64 citation statements)

References 61 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The g values for signals r 1 and r 2 fit the "rule of thumb" definition for the presence of intermediate spin iron used by many authors in analyses of rhombic EPR signals in other heme proteins and enzymes (42)(43)(44)(45) in that the g av ((g 1 ϩ g 2 )/2) values fall between 4 and 6. The high g 1 value for signal r 1 , however, is just beyond the range usually associated with rhombic EPR signals thought to represent quantum mechanically mixed spin (QS) heme and may be best assigned to 5-c HS heme.…”

Section: Resultsmentioning

confidence: 99%

Analysis of Heme Structural Heterogeneity in Mycobacterium tuberculosis Catalase-Peroxidase (KatG)

Chouchane

Girotto

Kapetanaki

et al. 2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

Mycobacterium tuberculosis catalase-peroxidase (KatG) is a heme enzyme considered important for virulence, which is also responsible for activation of the anti-tuberculosis pro-drug isoniazid. Here, we present an analysis of heterogeneity in KatG heme structure using optical, resonance Raman, and EPR spectroscopy. Examination of ferric KatG under a variety of conditions, including enzyme in the presence of fluoride, chloride, or isoniazid, and at different stages during purification in different buffers allowed for assignment of spectral features to both five-and six-coordinate heme. Five-coordinate heme is suggested to be representative of "native" enzyme, since this species was predominant in the enzyme examined immediately after one chromatographic protocol. Quantum mechanically mixed spin heme is the most abundant form in such partially purified enzyme. Reduction and reoxidation of sixcoordinate KatG or the addition of glycerol or isoniazid restored five-coordinate heme iron, consistent with displacement of a weakly bound distal water molecule. The rate of formation of KatG Compound I is not retarded by the presence of six-coordinate heme either in wild-type KatG or in a mutant (KatG[Y155S]) associated with isoniazid resistance, which contains abundant six-coordinate heme. These results reveal a number of similarities and differences between KatG and other Class I peroxidases.

show abstract

Section: Resultsmentioning

confidence: 99%

Analysis of Heme Structural Heterogeneity in Mycobacterium tuberculosis Catalase-Peroxidase (KatG)

Chouchane

Girotto

Kapetanaki

et al. 2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…This heme species is uncommon in biological systems. Known examples include the neutral pH form of cytochrome cЈ (51,52) and class III peroxidases (18, 23). Unfortunately, the biological significance and structural properties of the heme that give rise to the QS state remain obscure (24).…”

Section: Roles Of the Calcium Ions In Hrpcmentioning

confidence: 99%

The Critical Role of the Proximal Calcium Ion in the Structural Properties of Horseradish Peroxidase

Howes

Feis

Raimondi³

et al. 2001

Journal of Biological Chemistry

View full text Add to dashboard Cite

The extent to which the structural Ca 2؉ ions of horseradish peroxidase (HRPC) are a determinant in defining the heme pocket architecture is investigated by electronic absorption and resonance Raman spectroscopy upon removal of one Ca 2؉ ion. The Fe(III) heme states are modified upon Ca 2؉ depletion, with an uncommon quantum mechanically mixed spin state becoming the dominant species. Ca 2؉ -depleted HRPC forms complexes with benzohydroxamic acid and CO which display spectra very similar to those of native HRPC, indicating that any changes to the distal cavity structural properties upon Ca 2؉ depletion are easily reversed. Contrary to the native protein, the Ca 2؉ -depleted ferrous form displays a low-spin bis-histidyl heme state and a small proportion of high-spin heme. Furthermore, the (Fe-Im) stretching mode downshifts 27 cm ؊1 upon Ca 2؉ depletion revealing a significant structural perturbation of the proximal cavity near the histidine ligand. The specific activity of the Ca 2؉ -depleted enzyme is 50% that of the native form. The effects on enzyme activity and spectral features observed upon Ca 2؉ depletion are reversible upon reconstitution. Evaluation of the present and previous data firmly favors the proximal Ca 2؉ ion as that which is lost upon Ca 2؉ depletion and which likely plays the more critical role in regulating the heme pocket structural and catalytic properties.Peroxidases of the plant peroxidase superfamily are hemecontaining enzymes that oxidize a variety of aromatic molecules in the presence of hydrogen peroxide. They include peroxidases of plant, fungal, and prokaryotic origins that can be divided into three classes based on sequence alignment (1).Additional support for such a classification was gained as the crystal structures of representative enzymes of each class became available. Class I contains bacterial peroxidases and peroxidases from plant mitochondria and chloroplasts, for example most ascorbate peroxidases and cytochrome c peroxidase. Class II contains extracellular fungal peroxidases such as Coprinus cinereus peroxidase (a peroxidase essentially identical to Arthromyces ramosus peroxidase) and lignin-degrading peroxidases. Class III contains secretory plant peroxidases, typified by the classical horseradish peroxidase isoenzyme C (HRPC). The peroxidases of classes II and III share a number of structural elements considered to be of importance for maintaining protein stability and activity. These include calciumbinding sites proximal and distal to the heme and four disulfide bridges (1-5); the latter was in different locations in class II with respect to class III peroxidases. These features are absent in class I peroxidases. Class III peroxidases also have a loop insertion in the sequence, composed of the DЈ, FЈ, and FЉ helices, not found in the other classes. The relationship between calcium binding and enzyme inactivation has been treated primarily by studies on lignin peroxidase (LIP) (6, 7), manganese peroxidase (MNP) (8, 9), and HRPC (10, 11). Thermal (6) and alkaline (7) i...

show abstract

“…Although sharing just 19% sequence identity and 40% similarity (23), Cyt cЈ and Cyt b 562 have quite similar folds (1.6-Å rms deviation in ␣-carbon position) ( Fig. 1) (27)(28)(29)(30)(31)(32). In Cyt cЈ, the side-chain of Leu-12 fills the space occupied by a sixth ligand in Cyt b 562 (Fig.…”

mentioning

confidence: 99%

Cytochrome c ′ folding triggered by electron transfer: Fast and slow formation of four-helix bundles

Lee

Gray

Winkler

2001

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

E nergy-landscape descriptions of protein folding emphasize the roles of free energy and energy-surface ruggedness as key determinants of folding dynamics (1-3). The many correlations of folding times with free energy support this point of view, but it is difficult to reconcile the model with the seemingly simple kinetics that often are observed. Analyses of experimental data point to a relationship between the folding kinetics and the topology of the native protein structure (4-8). Proteins that, on average, have a large number of long-range contacts in the folded state tend to fold more slowly than those with a preponderance of short-range contacts. The questions remain: is it the depth and roughness of the funnel, the topology of the folded state, or some combination of the two that determines the folding mechanism? Short-range contacts outnumber long-range interactions in helical bundles; if topology is the key, then these proteins should fold rapidly (4, 5). Highly helical ferrocytochrome b 562 (Fe II -Cyt b 562 ) (9, 10), acyl-CoA binding protein (ACBP) (11)(12)(13)(14), the E colicin binding immunity proteins Im7 and Im9 (15,16), and the N-terminal domain of phage repressor (17) all fold on the millisecond time scale. These observations appear to support the notion that folded-state structural topology is of central importance in folding dynamics and that helical bundle structures are inherently fast folding.

show abstract

Electron paramagnetic resonance studies of ferric cytochrome c′ from photosynthetic bacteria

Cited by 46 publications

References 61 publications

Analysis of Heme Structural Heterogeneity in Mycobacterium tuberculosis Catalase-Peroxidase (KatG)

Analysis of Heme Structural Heterogeneity in Mycobacterium tuberculosis Catalase-Peroxidase (KatG)

The Critical Role of the Proximal Calcium Ion in the Structural Properties of Horseradish Peroxidase

Cytochrome c ′ folding triggered by electron transfer: Fast and slow formation of four-helix bundles

Contact Info

Product

Resources

About