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Journal Issue - Volume 1 Issue 5 (May 1992)

  • Who's on first?

  • Ralph A. Bradshaw
  • Published in Wiley Interscience on Dec 31, 2008
  • DOI: 10.1002/pro.5560010501 (p 561-562)

Abstract All retroviral nucleocapsid (NC) proteins contain one or two copies of an invariant 3Cys‐1His array (CCHC = C‐X2‐C‐X4‐H‐X4‐C; C = Cys, H = His, X = variable amino acid) that are essential for RNA genome packaging and infectivity and have been proposed to function as zinc‐binding domains. Although the arrays are capable of binding zinc in vitro, the physiological relevance of zinc coordination has not been firmly established. We have...

Abstract Although partial or complete three‐dimensional structures are known for three Class I aminoacyl‐tRNA synthetases, the amino acid‐binding sites in these proteins remain poorly characterized. To explore the methionine binding site of Escherichia coli methionyl‐tRNA synthetase, we chose to study a specific, randomly generated methionine auxotroph that contains a mutant methionyl‐tRNA synthetase whose defect is manifested in an elevated Km...

Abstract In an attempt to explore how specific features of the substrate's primary structure may affect the activity of rabbit muscle acylaminoacyl‐peptide hydrolase (EC 3.4.19.1), a number of acetylated peptides containing specific amino acid replacements in specific positions were prepared and compared as substrates for the hydrolase. The principal variants were d‐Ala, Pro, and positive charges (His, Arg, Lys); in addition, the effect of the...

Abstract The complete amino acid sequence of fibrolase, a fibrinolytic enzyme from southern copperhead (Agkistrodon contortrix contortrix) venom, has been determined. This is the first report of the sequence of a direct‐acting, non‐hemorrhagic fibrinolytic enzyme found in snake venom. The majority of the sequence was established by automated Edman degradation of overlapping peptides generated by a variety of selective cleavage procedures. The...

Abstract A combination of mass spectrometric techniques has been used to investigate the amino acid sequence and post‐translational modifications of αB‐crystallin isolated from bovine lenses by gel filtration chromatography and reversed‐phase high performance liquid chromatography. Chromatographic fractions were analyzed by electrospray ionization mass spectrometry to determine the homogeneity and molecular weights of proteins in...

Abstract Mutations were made in three highly conserved residues in Escherichia coli thioredoxin. An internal charged residue, Asp‐26, was changed to an alanine. The mutant protein was more stable than the wild type. It can function as a substrate for thioredoxin reductase with a 10‐fold increase in the Km over the wild type. Although the redox potential was not substantially changed from that of the wild type, thioredoxin D26A was a poor...

Abstract The N‐terminal DNA‐binding domain of the GAL4 transcription factor, isolated as a proteolytic fragment of 63 amino acid residues, GAL4(63), or cloned as a 62‐residue subdomain, GAL4(62*), binds 2 Cd(II) ions. Both Cd derivatives show intense ellipticity bands associated with ‐S− → Cd charge transfer bands at 250 nm (+), 233 nm (‐), and 218 nm (+). Molar ellipticity values are (5–7) x 104 deg · cm2 · dmol−1. The energies and pattern (+, ‐, +) of...

Abstract Recently we developed methods for the construction of knowledge‐based mean fields from a data base of known protein structures. As shown previously, this approach can be used to calculate ensembles of probable conformations for short fragments of polypeptide chains. Here we develop procedures for the assembly of short fragments to complete three‐dimensional models of polypeptide chains. The...

Abstract The tetramerization of melittin, a 26‐amino acid peptide from Apis mellifera bee venom, has been studied as a model for protein folding. Melittin converts from a monomeric random coil to an α‐helical tetramer as the pH is raised from 4.0 to 9.5, as ionic strength is increased, as temperature is raised or lowered from about 37 °C, or as phosphate is added. The thermodynamics of this tetramerization (termed “folding”) are explored using...

Abstract Thermal and GdmCl‐induced unfolding transitions of aldolase from Staphylococcus aureus are reversible under a variety of solvent conditions. Analysis of the transitions reveals that no partially folded intermediates can be detected under equilibrium conditions. The stability of the enzyme is very low with a ΔG0 value of ‐9 ± 2 kJ/mol at 20 °C. The kinetics of unfolding and refolding of aldolase are complex and comprise at least one ...

Abstract A neural network classification method is developed as an alternative approach to the large database search/organization problem. The system, termed Protein Classification Artificial Neural System (ProCANS), has been implemented on a Cray supercomputer for rapid superfamily classification of unknown proteins based on the information content of the neural interconnections. The system employs an n‐gram hashing function that...

Abstract The bifunctional reagent 1,4‐dibromobutanedione (DBBD) reacts covalently with pyruvate kinase from rabbit muscle to cause inactivation of the enzyme at a rate that is linearly dependent on the reagent concentration, giving a second order rate constant of 444 min−1 M−1. The individual substrates phosphoenolpyruvate (with KCl), ADP, or ATP in the presence of divalent metal cation provide marked protection against inactivation...

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