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Wilson GS. Spectroelectrochemistry of Proteins. ELECTROANAL 2021. [DOI: 10.1002/elan.202100535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- George S. Wilson
- Department of Chemistry University of Kansas Lawrence, KS USA 1-66045
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Pellaton C, Perrin Y, Boudousquié C, Barbier N, Wassenberg J, Corradin G, Thierry AC, Audran R, Reymond C, Spertini F. Novel birch pollen specific immunotherapy formulation based on contiguous overlapping peptides. Clin Transl Allergy 2013; 3:17. [PMID: 23725004 PMCID: PMC3672070 DOI: 10.1186/2045-7022-3-17] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 05/21/2013] [Indexed: 02/08/2023] Open
Abstract
Background Synthetic contiguous overlapping peptides (COPs) may represent an alternative to allergen extracts or recombinant allergens for allergen specific immunotherapy. In combination, COPs encompass the entire allergen sequence, providing all potential T cell epitopes, while preventing IgE conformational epitopes of the native allergen. Methods Individual COPs were derived from the sequence of Bet v 1, the major allergen of birch pollen, and its known crystal structure, and designed to avoid IgE binding. Three sets of COPs were tested in vitro in competition ELISA and basophil degranulation assays. Their in vivo reactivity was determined by intraperitoneal challenge in rBet v 1 sensitized mice as well as by skin prick tests in volunteers with allergic rhinoconjunctivitis to birch pollen. Results The combination, named AllerT, of three COPs selected for undetectable IgE binding in competition assays and for the absence of basophil activation in vitro was unable to induce anaphylaxis in sensitized mice in contrast to rBet v 1. In addition no positive reactivity to AllerT was observed in skin prick tests in human volunteers allergic to birch pollen. In contrast, a second set of COPs, AllerT4-T5 displayed some residual IgE binding in competition ELISA and a weak subliminal reactivity to skin prick testing. Conclusions The hypoallergenicity of contiguous overlapping peptides was confirmed by low, if any, IgE binding activity in vitro, by the absence of basophil activation and the absence of in vivo induction of allergic reactions in mouse and human. Trial registration ClinicalTrials.gov NCT01719133
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Affiliation(s)
- Céline Pellaton
- Division of Immunology and Allergy, Centre Hospitalier Universitaire Vaudois (CHUV), Rue du Bugnon, Lausanne, 1011, Switzerland.
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Fontana A, Vita C, Toniolo C. On the limited peptic digestion of horse heart cytochrome C. isolation of C-terminal peptide sequences. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 2009; 6:145-8. [PMID: 4370237 DOI: 10.1111/j.1399-3011.1974.tb02371.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Mathew R, Ramakanth M, Chatterji D. Deletion of the gene rpoZ, encoding the omega subunit of RNA polymerase, in Mycobacterium smegmatis results in fragmentation of the beta' subunit in the enzyme assembly. J Bacteriol 2005; 187:6565-70. [PMID: 16159791 PMCID: PMC1236636 DOI: 10.1128/jb.187.18.6565-6570.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A deletion mutation in the gene rpoZ of Mycobacterium smegmatis causes reduced growth rate and a change in colony morphology. During purification of RNA polymerase from the mutant strain, the beta' subunit undergoes fragmentation but the fragments remain associated with the enzyme and maintain it in an active state until the whole destabilized assembly breaks down in the final step of purification. Complementation of the mutant strain with an integrated copy of the wild-type rpoZ brings back the wild-type colony morphology and improves the growth rate and activity of the enzyme, and the integrity of the beta' subunit remains unaffected.
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Affiliation(s)
- Renjith Mathew
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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6
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Santoni E, Scatragli S, Sinibaldi F, Fiorucci L, Santucci R, Smulevich G. A model for the misfolded bis-His intermediate of cytochrome c: the 1-56 N-fragment. J Inorg Biochem 2005; 98:1067-77. [PMID: 15149817 DOI: 10.1016/j.jinorgbio.2004.02.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2003] [Revised: 02/09/2004] [Accepted: 02/19/2004] [Indexed: 10/26/2022]
Abstract
We have characterized the ferric and ferrous forms of the heme-containing (1-56 residues) N-fragment of horse heart cytochrome c (cyt c) at different pH values and low ionic strength by UV-visible absorption and resonance Raman (RR) scattering. The results are compared with native cyt c in the same experimental conditions as this may provide a deeper insight into the cyt c unfolding-folding process. Folding of cyt c leads to a state having the heme iron coordinated to a histidine (His18) and a methionine (Met80) as axial ligands. At neutral pH the N-fragment (which lacks Met80) shows absorption and RR spectra that are consistent with the presence of a bis-His low spin heme, like several non-native forms of the parental protein. In particular, the optical spectra are identical to those of cyt c in the presence of a high concentration of denaturants; this renders the N-fragment a suitable model to study the heme pocket microenvironment of the misfolded (His-His) intermediate formed during folding of cyt c. Acid pH affects the ligation state in both cyt c and the N-fragment. Data obtained as a function of pH allow a correlation between the structural properties in the heme pocket of the N-fragment and those of non-native forms of cyt c. The results underline that the (57-104 residues) segment under native-like conditions imparts structural stability to the protein by impeding solvent access into the heme pocket.
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Affiliation(s)
- Elisa Santoni
- Dipartimento di Chimica, Università di Firenze, Via della Lastruccia 3, I-50019 Sesto Fiorentino, Florence, Italy
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Beligere GS, Dawson PE. Conformationally Assisted Protein Ligation Using C-Terminal Thioester Peptides. J Am Chem Soc 1999. [DOI: 10.1021/ja9907919] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gangamani S. Beligere
- Departments of Cell Biology and Chemistry The Skaggs Institute for Chemical Biology The Scripps Research Institute La Jolla, California 92037
| | - Philip E. Dawson
- Departments of Cell Biology and Chemistry The Skaggs Institute for Chemical Biology The Scripps Research Institute La Jolla, California 92037
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8
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Ye D, Willhite DC, Blanke SR. Identification of the minimal intracellular vacuolating domain of the Helicobacter pylori vacuolating toxin. J Biol Chem 1999; 274:9277-82. [PMID: 10092603 DOI: 10.1074/jbc.274.14.9277] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Helicobacter pylori secretes a cytotoxin (VacA) that induces the formation of large vacuoles originating from late endocytic vesicles in sensitive mammalian cells. Although evidence is accumulating that VacA is an A-B toxin, distinct A and B fragments have not been identified. To localize the putative catalytic A-fragment, we transfected HeLa cells with plasmids encoding truncated forms of VacA fused to green fluorescence protein. By analyzing truncated VacA fragments for intracellular vacuolating activity, we reduced the minimal functional domain to the amino-terminal 422 residues of VacA, which is less than one-half of the full-length protein (953 amino acids). VacA is frequently isolated as a proteolytically nicked protein of two fragments that remain noncovalently associated and retain vacuolating activity. Neither the amino-terminal 311 residue fragment (p33) nor the carboxyl-terminal 642 residue fragment (p70) of proteolytically nicked VacA are able to induce cellular vacuolation by themselves. However, co-transfection of HeLa cells with separate plasmids expressing both p33 and p70 resulted in vacuolated cells. Further analysis revealed that a minimal fragment comprising just residues 312-478 functionally complemented p33. Collectively, our results suggest a novel molecular architecture for VacA, with cytosolic localization of both fragments of nicked toxin required to mediate intracellular vacuolating activity.
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Affiliation(s)
- D Ye
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204-5513, USA
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9
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Woods AC, Guillemette JG, Parrish JC, Smith M, Wallace CJ. Synergy in protein engineering. Mutagenic manipulation of protein structure to simplify semisynthesis. J Biol Chem 1996; 271:32008-15. [PMID: 8943249 DOI: 10.1074/jbc.271.50.32008] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Semisynthesis is a chemical technique of protein engineering that provides a valuable complement to directed mutagenesis. It is the method of choice when the structural modification requires, for example, a noncoded amino acid. The process involves specific and limited protein fragmentation, structural manipulation of the target sequence, and subsequent religation of fragments to give the mutant holoprotein. We suggested and demonstrated that mutagenesis and semisynthesis could be used synergistically to achieve protein engineering goals otherwise unobtainable, if mutagenesis was used to shuffle methionine residues in the yeast cytochrome c sequence (Wallace, C. J. A., Guillemette, J. G., Hibiya, Y., and Smith, M. (1991) J. Biol. Chem. 266, 21355-21357). These residues can not only be sites of specific cleavage by CNBr but also of spontaneous peptide bond synthesis between fragments in noncovalent complexes, which greatly facilitates the semisynthetic process. We have now used an informed "methionine scan" of the protein sequence to discover other useful sites and to characterize the factors that promote this extraordinary and convenient autocatalytic religation. Of eight sites canvassed, in a wide range of settings, five efficiently provoked peptide bond synthesis. The principal factor determining efficiency seems to be the hydropathy of the religation site. The mutants created have also provided some new insights on structure-function relationships in the cytochrome.
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Affiliation(s)
- A C Woods
- Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia B3H 4H7, Canada
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10
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Severinov K, Mustaev A, Severinova E, Bass I, Kashlev M, Landick R, Nikiforov V, Goldfarb A, Darst SA. Assembly of functional Escherichia coli RNA polymerase containing beta subunit fragments. Proc Natl Acad Sci U S A 1995; 92:4591-5. [PMID: 7753849 PMCID: PMC41990 DOI: 10.1073/pnas.92.10.4591] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The Escherichia coli rpoB gene, which codes for the 1342-residue beta subunit of RNA polymerase (RNAP), contains two dispensable regions centered around codons 300 and 1000. To test whether these regions demarcate domains of the RNAP beta subunit, fragments encoded by segments of rpoB flanking the dispensable regions were individually overexpressed and purified. We show that these beta-subunit polypeptide fragments, when added with purified recombinant beta', sigma, and alpha subunits of RNAP, reconstitute a functional enzyme in vitro. These results demonstrate that the beta subunit is composed of at least three distinct domains and open another avenue for in vitro studies of RNAP assembly and structure.
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Affiliation(s)
- K Severinov
- Rockefeller University, New York, NY 10021, USA
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11
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Shiba K, Schimmel P. Tripartite functional assembly of a large class I aminoacyl tRNA synthetase. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)50003-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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12
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Abstract
The sequence of a 939-amino acid polypeptide that is a member of the aminoacyl-tRNA synthetase class of enzymes has been aligned with sequences of 15 related proteins. This alignment guided the design of 18 fragment pairs that were tested for internal sequence complementarity by reconstitution of enzyme activity. Reconstitution was achieved with fragments that divide the protein at both nonconserved and conserved sequences, including locations proximal to or within elements believed to form critical elements of secondary structure. Structure assembly is sufficiently flexible to accommodate fusion of short segments of unrelated sequences at fragment junctions. Complementary chain packing interactions and chain flexibility appear to be widely distributed throughout the sequence and are sufficient to reconstruct large three-dimensional structures from an array of disconnected pieces. The results may have implications for the evolution and assembly of large proteins.
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Affiliation(s)
- K Shiba
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139
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13
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Wallace C, Clark-Lewis I. Functional role of heme ligation in cytochrome c. Effects of replacement of methionine 80 with natural and non-natural residues by semisynthesis. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)50604-4] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Yu LP, Smith GM. Characterization of pH-dependent conformational heterogeneity in Rhodospirillum rubrum cytochrome c2 using 15N and 1H NMR. Biochemistry 1990; 29:2920-5. [PMID: 2159779 DOI: 10.1021/bi00464a005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The 15N-enriched ferricytochrome c2 from Rhodospirillum rubrum has been studied by 15N and 1H NMR spectroscopy as a function of pH. The 15N resonances of the heme and ligand tau nitrogen are broadened beyond detection because of paramagnetic relaxation. The 15N resonance of the ligand histidine phi nitrogen was unambiguously identified at 184 ppm (pH 5.6). The 15N resonances of the single nonligand histidine are observed only at low pH, as in the ferrocytochrome because of the severe broadening caused by tautomerization. The dependence of the 15N and 1H spectra of the ferricytochrome on pH indicated that the ligand histidine tau NH does not dissociate in the neutral pH range and is involved in a hydrogen bond, similar to that in the reduced state. Because neither deprotonated nor non-hydrogen-bonded forms of the ligand histidine are observed in the spectra of either oxidation state, the participation of such forms in producing heterogeneous populations having different electronic g tensors is ruled out. Transitions having pKa's of 6.2, 8.6, and 9.2 are observed in the ferricytochrome. The localized conformational change around the omega loops is observed in the neutral pH range, as in the ferrocytochrome. Structural heterogeneity leads to multiple resonances of the heme ring methyl at position 8. The exchange rate between the conformations is temperature dependent. The transition with a pKa of 6.2 is assigned to the His-42 imidazole group. The displacement of the ligand methionine, which occurs with a pKa of 9.2, causes gross conformational change near the heme center.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L P Yu
- Department of Food Science and Technology, University of California, Davis 95616
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15
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Wallace CJA, Mascagni P, Chait BT, Collawn JF, Paterson Y, Proudfoot AEI, Kent SBH. Substitutions engineered by chemical synthesis at three conserved sites in mitochondrial cytochrome c. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84810-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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16
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Proudfoot AE, Rose K, Wallace CJ. Conformation-directed Recombination of Enzyme-activated Peptide Fragments: A Simple and Efficient Means to Protein Engineering. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)81859-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Fassina G, Chaiken IM. Sequence simplification and the intra- and intermolecular self-recognition properties of vasopressin/neurophysin biosynthetic precursor. J Mol Recognit 1989; 1:158-65. [PMID: 2631863 DOI: 10.1002/jmr.300010403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The self-assembly properties of the arginine 8-vasopressin/bovine neurophysin II (AVP/BNPII) biosynthetic precursor were studied using glycopeptide-deleted and sequence-redesigned semisynthetic derivatives. Semisynthetic precursors were prepared by chemically coupling synthetic vasopressinyl sequence domains and native protein-derived neurophysin II domain. Measurement of precursor-protein association by the extent of affinity chromatographic retardation on agarose-immobilized BNPII verified that the semisynthetic precursor with native AVP sequence has an enhanced self-association propensity similar to that predicted for native precursor. Here, the stabilizing contacts between hormone and neurophysin domains, mainly the positively charged protonated alpha-amino group and tyrosyl 2 side chain of the hormone, are retained. Semisynthetic precursor variants in which the hormone domain is sequence-simplified by introducing alanyl residues in positions not considered important for neurophysin recognition show non-reduced association to BNPII. In contrast, removal of one of the main contact elements between hormone and neurophysin by acetylation of the hormone alpha-amino group abolishes potentiation of precursor self-association. The results show that the presence of the C-terminal glycopeptide sequence domain of native vasopressin precursor is not required to promote self-assembly of the precursor. The data verify the view proposed for the oxytocinyl precursor that intramolecular domain interaction is the triggering event which promotes the increase in affinity of precursor self-association (intermolecular self-recognition). The data also define some of the intramolecular self-recognition elements in the folded precursor required for the high affinity intermolecular self-recognition.
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Affiliation(s)
- G Fassina
- National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892
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18
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Yu LP, Smith GM. pH-induced changes in Rhodospirillum rubrum cytochrome c2 and subsequent renaturation: an 15N NMR study. Proc Natl Acad Sci U S A 1988; 85:2894-8. [PMID: 2834719 PMCID: PMC280109 DOI: 10.1073/pnas.85.9.2894] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The 15N-enriched ferrocytochrome c2 from Rhodospirillum rubrum was studied by 15N NMR at different solvent pH values. The mobility and chemical shift of the N-terminal glutamic acid (335.4 ppm at pH 5.1) were found to depend on pH. It was least mobile between pH 8 and 9.0, which is explained in terms of pH-dependent conformational changes and formation of salt linkages and/or hydrogen bonds. The resonances of the lysine side chains are centered around 341.7 ppm at low pH and move upfield with pH by about 8.4 ppm with pKa values of 10.8. The exchange rates of the epsilon NH protons are lowest near their pKa values. The protein is very stable in the pH range between 4.9 and 10.0 but unfolds abruptly at pH 10.5-11. Denaturation was verified by the measurement of several parameters by NMR. The renaturation of the protein demonstrates that the folding begins with reformation of heme coordination and establishment of a hydrophobic core, followed by positioning of side chains and peptide backbones linking the nucleation centers. The repositioning processes had time scales of minutes to hours in contrast to the reported values of seconds in some studies.
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Affiliation(s)
- L P Yu
- Department of Food Science and Technology, University of California, Davis 95616
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19
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Wallace CJ, Proudfoot AE. On the relationship between oxidation-reduction potential and biological activity in cytochrome c analogues. Results from four novel two-fragment complexes. Biochem J 1987; 245:773-9. [PMID: 2822030 PMCID: PMC1148197 DOI: 10.1042/bj2450773] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have confirmed the propensity of fragments of cytochrome c to form complexes that reproduce the structure and, in part, the functionality, of the native protein by preparing four novel complexes. We have used trypsin under three different sets of conditions in sequence to prepare a contiguous two-fragment complex (1-55).(56-104). One of the intermediates is a stable overlapping complex (1-65).(56-104). Conditions for limited acid hydrolysis of peptide bonds in cytochrome c have been developed that optimize the yield of fragments (1-50) and (51-104). These two fragments also form a stable association, as do (1-50) and (56-104). These complexes are potentially useful for the semisynthesis of analogues modified in the region of the cleavage sites, which include a number of highly conserved amino acid residues, and are being used for studies of protein folding, interactions with oxidase, cytochrome c immunogenicity and of artificially induced spontaneous resyntheses between complexing fragments. Like other known two-fragment complexes of cytochrome c, they exhibit normal visible spectra, including the presence of the 695 nm band, indicative of a functional haem crevice. Studies of their biological activities and redox potentials lead to a number of conclusions on structure-function relationships in cytochrome c. Most significantly there is a linear relationship between the logarithm of electron-transfer rates from cytochrome c reductase and redox potential in this series of analogues, indicating that such transfer is thermodynamically controlled. This discovery contributes to our understanding of the interaction of cytochrome and reductase. Since the relationship is obeyed by other types of analogues, except for those that involve modification of the active site of cytochrome c, we have a useful diagnostic for those residues that participate directly in electron transfer.
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Affiliation(s)
- C J Wallace
- Département de Biochimie médicale-Université de Genève, Switzerland
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Wallace CJ, Corradin G, Marchiori F, Borin G. Cytochrome c chimerae from natural and synthetic fragments: significance of the biological properties. Biopolymers 1986; 25:2121-32. [PMID: 3034347 DOI: 10.1002/bip.360251107] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Wallace CJ. The effect of complete or specific partial acetimidylation on the biological properties of cytochrome c and cytochrome c-T. Biochem J 1984; 217:595-9. [PMID: 6324739 PMCID: PMC1153258 DOI: 10.1042/bj2170595] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The biological consequences of acetimidylation of all 19 epsilon-amino groups of horse cytochrome c are a slight decrease in both the redox potential of the protein and its ability to stimulate oxygen uptake in the cytochrome c-depleted-mitochondria assay. Examination of a number of specific partially acetimidylated analogues and acetimidylated cytochromes c of other species has shown that the changes in biological properties, which are associated with a slight structural change as monitored by n.m.r. spectroscopy [Boswell, Moore, Williams, Harris, Wallace, Bocieck & Welti (1983) Biochem. J. 213, 679-686], appear to stem from modification of residues in a restricted region of the sequence. The failure of the redox potential of Saccharomyces cerevisae cytochrome c to be affected by acetimidylation suggests that it is lysine-53, absent from that species, that is the sensitive residue.
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Wallace CJ, Rose K. The semisynthesis of analogues of cytochrome c. Modifications of arginine residues 38 and 91. Biochem J 1983; 215:651-8. [PMID: 6318729 PMCID: PMC1152448 DOI: 10.1042/bj2150651] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The arginine residues at positions 38 and 91 of horse cytochrome c are absolutely conserved throughout eukaryotic evolution. For studies of the functional roles of these residues, we have prepared, by semisynthetic techniques, analogues of cytochrome c in which one or the other of the arginine residues has been modified. The products of modification by adduct formation with pentane-2,4-dione were purified and extensively characterized. In biological tests, the arginine-91-modified cytochrome c showed little difference in behaviour from native horse cytochrome c. Modification of arginine-38, however, led to extensive changes in biological and chemical properties. We also prepared and tested adducts with cyclohexane-1,2-dione and camphorquinone-10-sulphonic acid. The same effects on biological properties were noted irrespective of the nature of the modifying group. We suggest reasons for the differences in sensitivity of the two sites.
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Hannum C, Ultee M, Matis LA, Schwartz RH, Margoliash E. The major B and T cell determinant on pigeon cytochrome c in B10.a mice. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1982; 150:37-51. [PMID: 6183946 DOI: 10.1007/978-1-4684-4331-8_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The specificities of B10.A B and T cells responding to pigeon cytochrome c have been examined. Proliferating T cells recognize glutamine 100 and lysine 104 and can be stimulated in vitro by either native cytochrome c molecules or certain of their CNBr-cleavage fragments. In contrast only molecules with the native cytochrome c conformation were found to interact with B10.A antipigeon cytochrome c antibodies. Antibodies appear to recognize a determinant or determinants which overlaps with that which elicits the T cell proliferative response.
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Juillerat M, Homandberg GA. Clostripain-catalyzed re-formation of a peptide bond in a cytochrome C fragment complex. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1981; 18:335-42. [PMID: 6273349 DOI: 10.1111/j.1399-3011.1981.tb02990.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Enzymatically-catalyzed condensation of cytochrome c fragments, ferrous heme fragment (1-38) and apofragment (39-104), has allowed the back-conversion of cytochrome c complex to native cytochrome c. The conversion was accomplished in 90% (v/v) glycerol, a solvent which has been shown to decrease the ionization of the terminal alpha-carboxyl group liberated during hydrolysis of a peptide bond. The effect on the pK is probably the main reason the thermodynamic obstacle to re-synthesis is minimized. A 30% conversion to cytochrome c was obtained. The cytochrome c product was distinguished from the non-covalent complex and separated fragments by molecular weight analysis with sodium dodecyl sulfate polyacrylamide gel electrophoresis, by elution from Sephadex G-50 and sulfopropyl-Sephadex in the presence of denaturant, by amino acid analysis of the product purified under complex-dissociation conditions, and by spectral analysis of the absorption bands of the heme. This method provides an opportunity to study the covalent rather than the complex form of cytochrome c analogs.
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26
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Corradin G, Chiller JM. Lymphocyte specificity to protein antigens. III. Capacity of low responder mice to beef cytochrome c to respond to a peptide fragment of the molecule. Eur J Immunol 1981; 11:115-9. [PMID: 6260510 DOI: 10.1002/eji.1830110210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Lymph node cells derived from A.TH or A.TL mice primed with beef cytochrome c show striking patterns of reactivity when assayed in vitro for antigen-induced T cell proliferation. Whereas cells from A.TH mice respond specifically to beef cytochrome c or peptides composed of amino acids 1-65 and 81-104, cells from A.TL mice respond neither to beef cytochrome c nor to peptide 1-65, but proliferate following exposure to either peptide 81-104 or to a cytochrome c hybrid molecule in which the N-terminal peptide of beef (1-65) was substituted by a similar peptide obtained from rabbit cytochrome c. Thus, T cells from mice phenotypically unresponsive to beef cytochrome may, in fact, contain populations of lymphocytes capable of responding to a unique peptide, the response to which is totally inhibited when the same fragment is presented in the sequence of the intact protein.
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27
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Parr G, Taniuchi H. Ordered complexes of cytochrome c fragments. Kinetics of formation of the reduced (ferrous) forms. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)70107-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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28
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Abstract
Semisynthesis provides a flexible approach for using chemical synthesis to produce large, biologically active polypeptides and analogues. Currently developing improvements in the basic methods used, including polypeptide fragmentation, peptide synthesis, and reconstitution of synthetic and native components, make this overall approach applicable to a variety of species. Sequence modification through semisynthesis thus provides a flexible route to explore the code of rules whereby primary structure directs higher order properties of folded conformation and biological function of large peptides and proteins. The fruits of this endeavor, an understanding of how these macromolecules work, and therein, a basis for design of new structures that ultimately may be produced directly or by recombinant DNA methods, have begun to emerge.
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29
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Berman P, Harbury H. Immunochemistry of cytochrome c. Identification of antigenic determinants through the study of hybrid molecules. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(18)43711-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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30
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Jemmerson R, Margoliash E. Topographic antigenic determinants on cytochrome c. Immunoadsorbent separation of the rabbit antibody populations directed against horse cytochrome. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(19)86371-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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31
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Corradin G, Chiller JM. Lymphocyte specificity to protein antigens. II. Fine specificity of T-cell activation with cytochrome c and derived peptides as antigenic probes. J Exp Med 1979; 149:436-47. [PMID: 84044 PMCID: PMC2184807 DOI: 10.1084/jem.149.2.436] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Murine T-lymphocyte specificity was determined in a system of antigen driven in vitro T-cell proliferation using cytochrome c molecules from different species, their derived peptides and reconstituted hybrid proteins. It was observed that primed T cells could discriminate between peptide fragments which differed from each other at a single amino acid residue. These conclusions were substantiated by the pattern of cross-reactivity noted in the response of closely related cytochrome c proteins as well as when artificial hybrid molecules reconstituted by the covalent linkage of peptide fragments were analyzed. The pattern of specificity observed appeared to be haplotype (BDF1) dependent although similar conclusions about the fine specificity of T cells in the response to cytochrome c have been obtained in other strains but associated with different residues.
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32
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Boon PJ, Tesser GI, Nivard RJ. Semisynthetic horse heart [65-homoserine]cytochrome c from three fragments. Proc Natl Acad Sci U S A 1979; 76:61-5. [PMID: 218205 PMCID: PMC382876 DOI: 10.1073/pnas.76.1.61] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Horse heart cytochrome c was treated with methylsulfonylethyloxycarbonyl succinimide (Msc-ONSu) to give fully N(epsilon)-protected cytochrome c. Treatment of this derivative with a hard base for 15 sec regenerated the native tetrahectapeptide chain. CNBr degradation of the protected compound produced three fragments bearing only protective Msc functions on epsilon-amino groups. The fragment comprising the sequence 81-104 was isolated from the mixture and acylated with N-hydroxysuccinimidyl-t-butyloxycarbonyl-L-methioninate. The resulting pentacosapeptide derivative was partially deprotected by treatment with acid and condensed in good yield (65%) with fully synthetic N(alpha66), N(epsilon72,73,79)- tetra-Msc-cytochrome-c-(66-79)-tetradecapeptide azide. This pathway is preferred because the pentadecapeptide azide derivative 66-80 acylated the N(epsilon)-protected tetracosapeptide sequence 81-104 in an unpredictable manner. Subsequent treatment of the product with a base produced unprotected semisynthetic cytochrome-c-(66-104)-nonatriacontapeptide, which is known to undergo acylation by unprotected [Hse(65)]cytochrome-c-(1-65)-pentahexacontapeptide lactone. The high specificity of this condensation is ascribed to "conformation direction." Semisynthetic [Hse(65)]cytochrome c thus prepared reacts like native cytochrome c with a succinate cytochrome c reductase preparation and with cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). This semisynthetic strategy may provide a rapid route for the production of cytochrome c analogs modified in the highly conservative sequence 66-80.
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33
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Parr G, Hantgan R, Taniuchi H. Formation of two alternative complementing structures from cytochrome c heme fragment (residue 1 to 38) and the apoprotein. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)30382-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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34
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35
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Osheroff N, Feinberg B, Margoliash E, Morrison M. Lactoperoxidase-catalyzed iodination of horse cytochrome c:monoiodotyrosyl 74 cytochrome c. J Biol Chem 1977. [DOI: 10.1016/s0021-9258(17)41031-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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36
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Barstow LE, Young RS, Yakali E, Sharp JJ, O'Brien JC, Berman PW, Harbury HA. Semisynthetic cytochrome c. Proc Natl Acad Sci U S A 1977; 74:4248-50. [PMID: 200910 PMCID: PMC431916 DOI: 10.1073/pnas.74.10.4248] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Horse heart cytochrome c can be split with cyanogen bromide into a heme peptide (residues 1-65) and a nonheme peptide (residues 66-104). In a process involving (i) complex formation between the two fragments and (ii) restoration of the severed peptide linkage, a fully active cytochrome c preparation can be re-formed. Use has been made of this process to couple the heme peptide to peptide 66-104 synthesized by the Merrifield solid-phase procedure. The semisynthetic product formed in this manner is indistinguishable from reconstituted cytochrome c prepared with nonsynthetic peptide 66-104.
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37
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Manjula BN, Acharya AS, Vithayathil PJ. Subtilisin modification of monodeamidated ribonuclease-A. Biochem J 1977; 165:337-45. [PMID: 921753 PMCID: PMC1164906 DOI: 10.1042/bj1650337] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Limited proteolysis of RNAase-Aa(1) (monodeamidated ribonuclease-A) by subtilisin results in the formation of an active RNAase-S type of derivative, namely RNAase-Aa(1)S. RNAase-Aa(1)S was chromatographically distinct from RNAase-S, but exhibited very nearly the same enzymic activity, antigenic conformation and susceptibility to trypsin as did RNAase-S. Fractionation of RNAase-Aa(1)S by trichloroacetic acid yielded RNAase-Aa(1)S-protein and RNAase-Aa(1)S-peptide, both of which are inactive by themselves, but regenerate active RNAase-Aa(1)S' when mixed together. RNAase-Aa(1)S-peptide was identical with RNAase-S-peptide, whereas the protein part was distinct from that of RNAase-S-protein. Titration of RNAase-Aa(1)S-protein with S-peptide exhibited slight but noticeably weaker binding of the peptide to the deamidated S-protein as compared with that of native protein. Unlike the subtilisin digestion of RNAase-A, which gives nearly 100% conversion into RNAase-S, the digestion of RNAase-Aa(1) gives only a 50% conversion. The resistance of RNAase-Aa(1) to further subtilisin modification after 50% conversion is apparently due to the interaction of RNAase-Aa(1) with its subtilisin-modified product. RNAase-S was also found to undergo activity and structural changes in acidic solutions, similar to those of RNAase-A. The initial reaction product (RNAase-Sa(1)) isolated by chromatography was not homogeneous. Unlike the acid treatment of RNAase-A, which affected only the S-protein part, the acid treatment of RNAase-S affected both the S-protein and the S-peptide region of the molecule.
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38
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Formation of a biologically active, ordered complex from two overlapping fragments of cytochrome c. J Biol Chem 1977. [DOI: 10.1016/s0021-9258(17)40665-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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39
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Ranweiler JS, Wilson G. Structural effects on cytochrome electron transfer: properties of HP1-65 from Horse Heart Cytochrome C. ACTA ACUST UNITED AC 1976. [DOI: 10.1016/0302-4598(76)85012-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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40
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Morrow JS, Gurd FR. Nuclear magnetic resonance studies of hemoglobin: functional state correlations and isotopic enrichment strategies. CRC CRITICAL REVIEWS IN BIOCHEMISTRY 1975; 3:221-87. [PMID: 3388 DOI: 10.3109/10409237509105453] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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41
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Miller WG, Cusanovich MA. Electron transport by C-type cytochromes. I. The reaction of horse heart cytochrome c with anionic reductants. BIOPHYSICS OF STRUCTURE AND MECHANISM 1975; 1:97-111. [PMID: 10021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The kinetics of reduction of horse heartcytochrome c have been investigated using the reductants sodium dithionite and potassium ferrocyanide. Sodium dithionite reduction at pH 7.0 yields rate constants of 2.8 X 10(8)M(-1)sec-1 for SO2 AND 6 X 10(5) M-1 sec-1 for S2O4 at infinite dilution. Moreover, the data presented demonstrates the participation of positively charged amino acid side chains at the site of electron transfer. The effect of pH on the reduction of ferricytochrome c requires a minimum of two pK values for description (pK1 = 7.0 +/- 0.4, pK2 = 9.3 +/- 0.3). Based on the pK values determined, one or more lysines and a residues(s) with a low pK are implicated as the positively charged residues participating in electron transfer. From a comparison of the rates of reduction of various denatured forms of cytochrome c we feel that the most viable conclusion is that electron transfer takes place at the exposed heme edge in the vicinity of the amino acid side chains indicated above. Ferrocyanide reduction of ferri-horse heart cytochrome c takes place in a kinetically complex manner. A mechanism is described which includes complexes of ferrocyanide and ferricytochrome c and ferricyanide and ferrocytochrome c. As was found for dithionite reduction a positively charged region of the cytochrome c participates in electron transfer. Combining our results with ferrocyanide and dithionite we conclude that avaible data is compatible with a single mechanism of electron transfer. It is suggested that the kinetic distinction between different reductants lies in the lifetime of the transient complex formed, with the order ferrocyanide greater than S2O4 greater than SO2.
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42
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Slaby I, Holmgren A. Reconstitution of Escherichia coli thioredoxin from complementing peptide fragments obtained by cleavage at methionine-37 or arginine-73. J Biol Chem 1975. [DOI: 10.1016/s0021-9258(19)41819-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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43
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O'Hern JO, Pal PK, Myer YP. Conformational and functional studies of chemically modified cytochromes: N-bromosuccinimide- and formyl-cytochromes c. Biochemistry 1975; 14:382-91. [PMID: 164205 DOI: 10.1021/bi00673a027] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
N-bromosuccinimide-cytochromes c (Myer, Y. P. (1972), Biochemistry 11, 4195) and formyl-cytochrome c (Aviram, I and Schejter, A. (1971), Biochim. Biophys. Acta 229, 113) have been chromatographically purified, and the resulting components have been characterized in terms of their structure, conformation, and function. The activity measurements are considered in terms of the oxidizability, as the transference of an electron to solubilized cytochrome c oxidase, and reducibility, as the tendency to accept an electron from NADH-cytochrome c reductase. Conformational characterization has been carried out by absorption measurements, pH-spectroscopic behavior, circular dichroism, thermal denaturation, ionization of phenolic hydroxyls, the tendency to form the CO complex, and autoxidation with molecular oxygen. NBS-cytochrome c yields two major components, the relative proportions of which, with increasing modification of the protein, exhibit a pattern typical of the formation of the two in a consecutive manner. The first product contains the modification of the Trp-59 and Met-65 side chains, and the second contains the added modification of Met-80. The former in both valence states of iron is more or less like the native protein, except for an apparently slightly loosened heme crevice; the latter, as in other modifications involving modification of centrally coordinated Met-80, was found to be in a conformational state characteristic of the native protein with a disrupted central coordination complex, a loosened heme crevice, and small, but finite derangement of the polypeptide conformation. Functionally, the first component reflected 55% of the reducibility property and an unimpaired oxidizability property, while the latter exhibited derangement of both aspects of cytochrome c activity. Formyl-cytochrome c yielded a single component with modification of Trp-59. Conformationally, in both valence states, it is a molecular form with a disrupted central coordination complex, a loosened heme crevice, and gross derangement of the overall protein conformation. It exhibits a minimal reducibility property, 12%, whereas it retains a native-like tendency to transfer an electron to cytochrome c oxidase. The data from the NBS-cytochrome c components are analyzed with reference to the two forms in the earlier studies of the unpurified preparations. The results are found to be in agreement with one another. The selectivity between the reducibility and the oxidizability exhibited by the first NBS component and formyl-cytochrome c, irrespective of significant differences in the conformational and coordinational configurations of the two, has been viewed in light of a two-path, two-function model for oxidoreduction, as well as with reference to conformational and structural requirements for the oxidizability and reducibility properties of the molecule.
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44
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Toniolo C, Fontana A, Scoffone E. Conformational studies of equilibrium structures in fragments of horse heart cytochrome c. EUROPEAN JOURNAL OF BIOCHEMISTRY 1975; 50:367-74. [PMID: 165078 DOI: 10.1111/j.1432-1033.1975.tb09812.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ultraviolet absorption and circular dichroism studies have been carried out on horse heart apo-cytochrome c and heme-free peptide fragments obtained by cyanogen bromide cleavage of the native protein. It was noted that the various peptides assume predominantly an unordered conformation in water solution. Increasing ionic strength and addition of 2-chloroethanol increase the right-handed helical content. Guanidinium hydrochloride favors the coil state. It was also demonstrated that two non-interacting helical regions of different stability are present in the apo-protein in 2-chloroethanol.
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45
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46
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Wilgus H, Stellwagen E. Alkaline isomerization of ferricytochrome c: identification of the lysine ligand. Proc Natl Acad Sci U S A 1974; 71:2892-4. [PMID: 4368392 PMCID: PMC388578 DOI: 10.1073/pnas.71.7.2892] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Changes in the visible absorbance spectra of complexes of horse heart cytochrome c hemopeptide 1-65, peptide 66-104, and their guanidinated counterparts are compared with those characteristic of native and fully guanidinated ferricytochrome c over the pH range 7 to 11. Upon raising the pH, the methionine ligand in the guanidinated hemopeptide 1-65.peptide 66-104 complex is replaced by a strong field ligand. By contrast, the methionine ligand in the hemopeptide 1-65.guanidinated peptide 66-104 is replaced by a weak field ligand. These results demonstrate that lysine 13 does not ligate with the heme iron upon isomerization of ferricytochrome c and that the ligand in the horse heart protein is one of the eight lysine residues in the 66-104 segment of the polypeptide, most likely lysine 79.
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47
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Strickland EH. Aromatic contributions to circular dichroism spectra of proteins. CRC CRITICAL REVIEWS IN BIOCHEMISTRY 1974; 2:113-75. [PMID: 4591332 DOI: 10.3109/10409237409105445] [Citation(s) in RCA: 578] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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48
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49
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Fisher WR, Taniuchi H, Anfinsen CB. On the Role of Heme in the Formation of the Structure of Cytochrome c. J Biol Chem 1973. [DOI: 10.1016/s0021-9258(19)44026-x] [Citation(s) in RCA: 307] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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50
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Moroder L, Marchiori F, Borin G, Scoffone E. Studies on cytochrome c. VI. Synthesis of the protected pentadecapeptide (sequence 64-81) of Baker's yeast iso-1-cytochrome c. Biopolymers 1973; 12:701-20. [PMID: 4348685 DOI: 10.1002/bip.1973.360120403] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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