Relative Conformations of Sperm Whale Metmyoglobin and Apomyoglobin in Solution

Breslow, Esther; Beychok, Sherman; Hardman, Karl D.; Gurd, Frank R. N.

doi:10.1016/s0021-9258(18)97649-0

Cited by 192 publications

(54 citation statements)

References 22 publications

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“…The CD spectra of untreated apomyoglobin (Breslow et al, 1965) and BSA both show two minima in the ultraviolet region, at 208 and 222 m (Figs. 1, 2).…”

Section: Resultsmentioning

confidence: 99%

Alteration of the Conformation of Proteins in Red Blood Cell Membranes and in Solution by Fixatives Used in Electron Microscopy

Lenard

Singer

1968

The Journal of Cell Biology

185

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The effects of several commonly employed fixatives on the three-dimensional conformations of two soluble proteins and the protein of intact red blood cell membranes have been studied by means of circular dichroism measurements in the spectral region of the peptide absorption bands. The fixatives used produced significant and parallel conformational changes in all of the proteins, in the increasing order: glutaraldehyde; OsO 4 ; glutaraldehyde followed by OsO 4 ; and KMnO 4 . The last two treatments obliterated most of the helical character of the proteins. The significance of these observations to the preparation of specimens for electron microscopy is discussed.

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“…The CD spectra of untreated apomyoglobin (Breslow et al, 1965) and BSA both show two minima in the ultraviolet region, at 208 and 222 m (Figs. 1, 2).…”

Section: Resultsmentioning

confidence: 99%

Alteration of the Conformation of Proteins in Red Blood Cell Membranes and in Solution by Fixatives Used in Electron Microscopy

Lenard

Singer

1968

The Journal of Cell Biology

185

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“…Moreover, the high rate of recombination of the ockchain sub-units with Hb-4Al and the fact that they combine reversibly with oxygen (Ranney et al 1965) also support the previous contention ) that the ocAkchain sub-units retain a compact and probably specific conformation. Indeed, Breslow, Beychok, Hardman & Gurd (1965) and Harrison & Blout (1965) have shown that even apomyoglobin retains much of the conformation of myoglobin. The release of ocAkchain sub-units from the unstable f-chain haemoglobin variants presumably arises because the abnormal fl-chain sub-units differ sufficiently in conformation from the normal sub-units for the interaction between a-and P-chains to be significantly decreased.…”

Section: Discussionmentioning

confidence: 99%

Further studies on the isolation and properties of α-chain sub-units of haemoglobin

Huehns

Shooter

1966

Biochemical Journal

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1. alpha(A)-Chain sub-units have been isolated from neutral haemolysates containing certain unstable beta-chain haemoglobin variants. They are identical, in electrophoretic properties, tryptic peptide analyses and their ability to recombine with Hb-beta(A) (4) at neutral pH, with the alpha(A)-chain sub-units isolated from Hb-A at acid pH. Abnormal alpha(G)-chain sub-units have been prepared from haemolysates containing the alpha-chain variant Hb-G. 2. alpha(A)-Chain sub-units prepared by either method are eluted from Sephadex at low haemoglobin concentration as monomer sub-units. The elution volume, sedimentation coefficient and apparent molecular weight are, however, concentration-dependent, suggesting an equilibrium between monomers and higher polymers with the former as the predominant species. Elevated temperatures cause the alpha(A)-chain sub-unit to aggregate and denature. 3. The product of the reaction between the alpha(A)-chain sub-unit and Hb-beta(A) (4) has been characterized as Hb-A. Only Hb-A and Hb-G can be detected as the products when a mixture of alpha(A)- and alpha(G)-chain sub-units reacts with Hb-beta(A) (4). The absence of the species alpha(A)alpha(G)beta(A) (2) can be explained in terms of the rapid equilibrium between whole and half haemoglobin molecules and the reassortment of alphabeta sub-units during the separation process.

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“…In addition, we studied a second intact but structurally altered form of myoglobin, apomyoglobin'. The removal of the heme in the preparation of apomyoglobin deprives the molecule of an important internal stabilizing component and produces a more flexible polypeptide structure relative to native myoglobin (27)(28)(29) (see below). The presentation of native myoglobin was inhibited by leupeptin, whereas that of fragment, of apomyoglobin, and of S-methylmyoglobin was not inhibited.…”

Section: Resultsmentioning

confidence: 99%

“…Similarly, the fragment cannot bury its hydrophobic residues as well as the native protein. Apomyoglobin, although less denatured than S-methylmyoglobin, has 15-20% less a-helical content and is more flexible because of the removal of the heme that bridges several helices (28,29). The greater flexibility of apomyoglobin compared to native myoglobin was also demonstrated by the accessibility to specific modifying reagents of residues not accessible in the native form (27)(28)(29).…”

Section: Resultsmentioning

confidence: 99%

“…Apomyoglobin, although less denatured than S-methylmyoglobin, has 15-20% less a-helical content and is more flexible because of the removal of the heme that bridges several helices (28,29). The greater flexibility of apomyoglobin compared to native myoglobin was also demonstrated by the accessibility to specific modifying reagents of residues not accessible in the native form (27)(28)(29). The energy required to unfold apomyoglobin must therefore be considerably less than that of the native form, as witnessed by the greater ease of denaturation.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Antigen conformation determines processing requirements for T-cell activation

1985

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

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We studied the difference in requirements for processing and presentation to a single T-cell clone of four different forms of the same epitope of sperm whale myoglobin-namely, on the native protein, on two conformationally altered forms of the protein, or as a 22-residue antigenic peptide fragment. The T-cell clone was I-Ed-restricted and specific for an epitope on the CNBr fragment 132-153 involving Lys-140. As inhibitors of macrophage processing of antigen, we used several agents that inhibit lysosomal function: the weak bases chloroquine and NH4CI, the cationic ionophore monen-

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Relative Conformations of Sperm Whale Metmyoglobin and Apomyoglobin in Solution

Cited by 192 publications

References 22 publications

Alteration of the Conformation of Proteins in Red Blood Cell Membranes and in Solution by Fixatives Used in Electron Microscopy

Alteration of the Conformation of Proteins in Red Blood Cell Membranes and in Solution by Fixatives Used in Electron Microscopy

Further studies on the isolation and properties of α-chain sub-units of haemoglobin

Antigen conformation determines processing requirements for T-cell activation

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