Biomaterial Database

Conformation of Escherichia coli ribosomal protein L7/L12 in solution: hydrodynamic, spectroscopic, and conformation prediction studies. 1979

C A Luer, and K P Wong

The conformation of Escherichia coli ribosomal protein L7/L12 in solution has been studied using spectroscopic and hydrodynamic methods. Circular dichroism studies in the near-ultraviolet region reveal two bands at 262 and 268 nm originating from the tertiary conformational environment of the phenylalanyl residues. Additional characterization of the phenylalanine environment includes an intrinsic fluorescence emission spectrum arising from the phenylalanine fluorophores. Computer analysis of the far-ultraviolet circular dichroism spectrum suggests that L7/L12 contains as much as approximately 76% alpha helix. Hydrodynamic properties of L7/L12, measured with the purpose of providing relevant shape information, include the frictional coefficient ratio (1.84 +/- 0.03) and intrinsic viscosity (28 +/- 0.4 mL/g). The experimentally determined frictional coefficient (6.15 +/- 0.15 X 10(-8) has been compared with theoretical calculations of the same value employing two independent methods and assuming various dimensions for the L7/L12 dimer. Combining the experimental results from this work with those available from the literature, and using conformation predictive methods of Chou & Fasman [P. Y. Chou & G. D. Fasman (1974) Biochemistry 13, 211-222, 222-245] and of Maxfield & Scheraga (F. R. Maxfield & H. A. Scheraga (1976) Biochemistry 15, 5138-5153), several possible molecular models of the L7/L12 dimer have been constructed and critically examined. A model which is consistent with all of the available data is proposed.

UI	MeSH Term	Description	Entries
D008958	Models, Molecular	Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.	Molecular Models,Model, Molecular,Molecular Model
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D002458	Cell Fractionation	Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS.	Cell Fractionations,Fractionation, Cell,Fractionations, Cell
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D012269	Ribosomal Proteins	Proteins found in ribosomes. They are believed to have a catalytic function in reconstituting biologically active ribosomal subunits.	Proteins, Ribosomal,Ribosomal Protein,Protein, Ribosomal
D012270	Ribosomes	Multicomponent ribonucleoprotein structures found in the CYTOPLASM of all cells, and in MITOCHONDRIA, and PLASTIDS. They function in PROTEIN BIOSYNTHESIS via GENETIC TRANSLATION.	Ribosome
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence
D013056	Spectrophotometry, Ultraviolet	Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Ultraviolet Spectrophotometry