Structure of Yeast Cytochrome c

Motonaga, Kazuo; Katano, Hamako; Nakanishi, Kazuo

doi:10.1093/oxfordjournals.jbchem.a128052

Cited by 11 publications

(10 citation statements)

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“…The results of these studies on the acetamide-derivatized monomer of iso-1 cytochrome c clearly show that protein conformations intermediate between monomer and dimer forms are possible, depending on the polarity and charge of the modifying group. Such a conclusion is consistent with results of protease digestion and denaturation studies of Montonaga et al (1965b) and Bryant et al (1985) performed on the sulfiteand iodoacetate-derivatized monomer of iso-1 cytochrome c. More detailed analyses of the structural alterations induced by Cys-102 modification of iso-1 ferricytochrome c must await characterization of the protein derivatives by X-ray diffraction or multidimensional NMR methods.…”

Section: Discussionsupporting

confidence: 78%

“…The proton NMR changes occurring upon dimerization were of an extent to warrant the suggestion that a possible regulatory site exists at position 102 in yeast iso-1 cytochrome c which might have a physiological role in altering the conformation of the molecule as a means of modulating the function of the protein. A similar suggestion was made 30 years ago by Montonaga et al (1965b) on the basis of the results of the protease digestion and denaturation studies performed on iso-1 ferricytochrome c monomer and dimer, mentioned earlier. In contrast, proton NMR studies on iso-1 ferricytochrome c modified at Cys-102 with an -SCH3 indicated that a conformation similar to the native, unmodified monomer, protein was maintained (Busse et al, 1990).…”

Section: Introductionsupporting

confidence: 74%

“…In conclusion, it was 30 years ago that Montonaga et al (1965b) first hypothesized that the dimer conformation of iso-1 cytochrome c might resemble the conformation of the protein substrate found in an enzyme-substrate complex. It is conceivable that modification of Cys-102 of iso-1 cytochrome c by certain specific groups on redox partner proteins or by certain molecules (i.e., lipids) triggers a type of "molecular switch" which alters the conformation of the cytochrome c so as to facilitate the electron transfer process.…”

Section: Discussionmentioning

confidence: 92%

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A comparison of spectral and physicochemical properties of yeast iso-1 cytochrome c and Cys 102-modified derivatives of the protein

Moench¹,

Satterlee²

1995

J Protein Chem

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Derivatives of yeast iso-1 cytochrome c, chemically modified at Cys-102 (Cys-102 acetamide-derivatized monomer, Cys-102 thionitrobenzoate-derivatized monomer, Cys-102 S-methylated monomer, and the disulfide dimer), exhibit different spectral and physicochemical properties relative to the native, unmodified protein, depending on the nature of the modifying group. The results of proton NMR studies on the Cys-102 acetamide-derivatized monomer of iso-1 ferricytochrome c indicate that the conformational characteristics of the heme environment in this protein derivative are intermediate between those of the unmodified monomer and disulfide dimer forms of the protein. Measurements of the pKa of the alkaline transitions of the five forms of iso-1 ferricytochrome c provided values of 8.89, 8.82, 8.67, 8.47, and 8.50 for the unmodified monomer, S-methylated monomer, acetamide-derivatized monomer, thionitrobenzoate-derivatized monomer, and disulfide dimer, respectively. The results of proton NMR studies of the reduced form of these proteins suggest that the heme environments of the unmodified monomer and disulfide dimer derivatives of iso-1 ferrocytochrome c are similar and indicate that treatment of the thionitrobenzoate-derivatized and disulfide dimer forms of the protein with sodium dithionite results in cleavage of the disulfide bonds at position 102. Circular dichroism studies reveal that only the disulfide dimer form of iso-1 ferricytochrome c exhibits a Soret CD spectrum which differs from the native, unmodified monomer in that the intensity of the negative band at approximately 420 nm is diminished in the spectrum of the dimer relative to the spectrum of the monomer. Soret CD spectra of the ascorbate-reduced form of all protein derivatives are similar. The process of "autoreduction" of yeast iso-1 ferricytochrome c is shown to occur in the absence of a free sulfhydryl group at position 102 and is exacerbated under moderately high pH conditions. These results are suggestive of the presence of a redox-active amino acid, perhaps a tyrosine, in yeast iso-1 cytochrome c.

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Section: Discussionsupporting

confidence: 78%

Section: Introductionsupporting

confidence: 74%

Section: Discussionmentioning

confidence: 92%

See 1 more Smart Citation

A comparison of spectral and physicochemical properties of yeast iso-1 cytochrome c and Cys 102-modified derivatives of the protein

Moench¹,

Satterlee²

1995

J Protein Chem

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“…This is well known as a feature in which the plots of observed H and Q as mentioned above exhibit "a counterclockwise loop." 3) Motonaga et al 4) indicated that a non-negligible difference can occur between the discharge converted from the stage measured by an automatic water gauge by using a HQ curve (hereafter, the discharge is termed as "HQdischarge") and the actual observed discharge (hereafter, the discharge is termed as "Obs.-discharge") at the rising period and falling period of the flood due to the feature of the high water observation data at the I-Observatory in the I-river, which is a first-class river in Japan, and the HQ curve actually established by the observed data from the observatory. Conversely, they also indicated that the HQ-discharge and Obs.-discharge are nearly equal at the flood peak.…”

Section: Introductionmentioning

confidence: 99%

“…In the case where the HQ curves do not represent the actual river discharge, Motonaga et al 4) proposed the HK curve method in which the HK curve is used as opposed to the HQ curve. The HK curve represents the relation between water stage H and conveyance K 5) .…”

Section: Introductionmentioning

confidence: 99%

Accuracy Verification of Discharge Computed by the Hk-Curve and Estimation of Missing Data by Using the Curve

Motonaga¹,

Kuriki²

2020

Journal of JSCE

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Compared with the conventional HQ-curve method, the HK-curve method computes river discharge Q more accurately by considering hydrological data at water level H and water-surface slope i. In the analysis, the actual observed hydrological data during the flood is used, and the results indicated that the error of the computed Q by the HK-curve method for the observed value was less than almost 5%, while the error of the computed Q by the HQ-curve method occasionally exceeded 10%. Additionally, the results suggested that the HK-curve was almost identical to the one that considered the whole observed data from the river rising period to the river falling period via peak time during the flood although only the data in the period of drawdown were used. Thus, even when the data were observed only in the drawdown period of flood, the HK-curve method estimated highly accurate missing Q at the river rising period.

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