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  • 1
    ISSN: 1573-4943
    Keywords: β-chain ; hemoglobin ; rose-ringed parakeet ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The primary structure of Rose-ringed Parakeet hemoglobin β-chain was established, completing the analysis of this hemoglobin. Comparisons with other avian β-chains show variations smaller than those for the corresponding α-chains. There are 11 amino acid exchanges in relationship to the only other characterized psittaciform β-chain, and a total of 35 positions are affected by differences among all avian β-chains analyzed (versus 61 for the α-chains). At three positions, the Psittacula β-chain has residues unique to this species. Three α1β1 contacts are modified, by substitutions at positions β51, β116, and β125.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-4943
    Keywords: hemoglobin ; structural analysis ; molecular evolution ; avian relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structure of the hernoglobin α-chain of Rose-ringed Parakeet was determined by sequence degradations of the intact subunit, the CNBr fragments, and peptides obtained by digestion with staphylococcal Glu-specific protease and trypsin. Using this analysis, the complete α-chain structure of 21 avian species is known, permitting comparisons of the protein structure and of avian relationships. The structure exhibits differences from previously established avian α-chains at a total of 61 positions, five of which have residues unique to those of the parakeet (Ser-12, Gly-65, Ser-67, Ala-121, and Leu-134). The analysis defines hemoglobin variation within an additional avian order (Psittaciformes), demonstrates distant patterns for evaluation of relationships within other avian orders, and lends support to taxonomic conclusions from molecular data.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-4943
    Keywords: Amino acid sequence ; post translational modification ; peptide analysis ; isozymes ; high-performance liquid chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The class III human liver alcohol dehydrogenase, identical to glutathione-dependent formaldehyde dehydrogenase, separates electrophoretically into a major anodic form (χ1) of known structure, and at least one minor, also anodic but a slightly faster migrating form (χ2). The primary structure of the minor form isolated by ion-exchange chromatography has now been determined. Results reveal an amino acid sequence identical to that of the major form, suggesting that the two derive from the same translation product, with the minor form modified chemically in a manner not detectable by sequence analysis. This pattern resembles that for the classical alcohol dehydrogenase (class I). Hence, the χ1/χ2 multiplicity does not add further primary forms to the complex alcohol dehydrogenase system but shows the presence of modified forms also in class III.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 11 (1991), S. 176-183 
    ISSN: 0887-3585
    Keywords: active site model ; thiolester mechanism ; multiple alignment ; three-dimensional correlations ; conservation of glycines ; conservation of functional cysteines ; conservation of salt bridges ; exon boundaries ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The C-terminal 222 residues of human liver aldehyde dehydrogenase can be aligned with the C-terminal 226 residues of a thiol protease from Dictyostelium discoideum to yield 47 residue identities, including matching active site cysteine residues. A multiple alignment with three more aldehyde dehydrogenases and three more thiol proteases yields three regions with clustered residue similarities. In the tertiary structure of papain, these three regions are in close proximity although widely separated in primary structure, and many conserved residues are located in the active site groove. The three-dimensional relationships, the common thiol ester mechanisms of the enzymes, the locations of exon boundaries in the dehydrogenase and protease genes, and the conservation of internal salt-bridging and disulfide-paired residues in papain, all appear compatible with the hypothesis of an ancestral relationship between thiol proteases and aldehyde dehydrogenases.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The technique of electroblotting polypeptides onto Polybrene-treated glass fiber filter discs after protein detection with potassium chloride is evaluated further with different proteins in separate applications. The number of proteins analyzed with this method is now more than double that previously reported. Reproducible results in good yield are obtained. Average overall yield - including the electrophoretic step before blotting - is 26 %, with maximal recoveries through all steps up to 60 %. High sensitivity radiosequence analysis is also applicable. Recent modification of the previously described procedure include use of Whatman glass fiber filters, removal of air in the Polybrene-impregnated filters by buffer penetration under reduced pressure, and use of widely different times for electrotransfer. Special advantages with this method are low extent of protein α-amino group destruction, direct use of the entire filter in the sequencer, and insensitivity to variations in electroblotting time. Gas-phase hydrolysis in situ of blotted proteins followed by amino acid analysis is known to give a low yield of polar amino acids, and often artifacts, but can still give an estimate of the amount of polypeptide immobilized on the filter. A wash with n-butyl chloride is now shown to reduce the Polybrene-associated artifacts, and an addition of sodium chloride to increase the recovery of polar amino acids. These two steps therefore appear interesting in schemes for compositional analyses of electroblotted proteins.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0173-0835
    Keywords: Breast ; Tumor ; Two-dimensional polyacrylamide gel electrophoresis ; Polypeptide expression ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Results of two-dimensional electrophoresis (2-DE) analyses of human breast carcinoma are described. Tumor cells were extracted and purified from breast carcinomas with different proliferative indeces and degrees of genomic stability. Cells purified from fibroadenoma tissue served as controls for benign cells. The following results were observed: (i) Analysis of samples from different areas of the same tumor showed a high degree of similarity in the pattern of polypeptide expression. Similarly, analysis of two tumors and their metastases revealed similar 2-DE profiles. (ii) In contrast, large variations were observed between different lesions with comparable histological characteristics. Larger differences in polypeptide expression were observed between potentially highly malignant carcinomas compared to comparisons of less malignant lesions. These differences were in the same order of magnitude as those observed comparing a breast carcinoma to a lung carcinoma. (iii) The levels of all cytokeratin forms resolved (CK7, CK8, CK15, and CK18) were significantly lower in carcinomas compared to fibroadenomas. (iv) The levels of high molecular weight tropomyosins (1-3) were lower in carcinomas compared to fibroadenomas. The expression of tropomyosin-1 was found to be 1.7-fold higher in primary tumors with metastatic spread to axillar lymph nodes compared to primary tumors with no evidence of metastasis (p 〈 0.05). (v) The expression of proliferating cell nuclear antigen (PCNA) and some members of the stress protein family (pHSP60, HSP90, and calreticulin) were higher in carcinomas. We conclude that malignant progression of breast carcinomas results in large heterogeneity in polypeptide expression between different tumors, but that some common themes such as decreased expression of cytokeratin and tropomyosin polypeptides can be discerned.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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