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T S Baker

Publications and source records attributed to T S Baker.

At least 109 records · Page 6Linked to original sources
PubMed1979

The three-dimensional structure of tubulin protofilaments.

A three-dimensional image of tubulin protofilaments, reconstructed to 20 A resolution from electron micrographs of negatively stained zinc-induced sheets, has been used to generate an improved model for microtubule substructure. This model has been used to phase a reconstructed image from X-ray amplitudes, which is compatible with the electron microscope results.

Crystallography↗
PubMed1979

The direct radioimmunoassay of oestrogen glucuronides in human female urine.

Radioimmunoassays for five oestrogen metabolites in urine are described; they are oestrone 3-glucuronide, oestradiol 3-glucuronide, oestradiol 17 beta-glucuronide, oestriol 3-glucuronide and oestriol 16 alpha-glucuronide. These assays have proved accurate and reliable and can be performed rapidly; they have been carried out directly in diluted menstrual cycle urine and pregnancy urine. No sample pretreatment was required. Preliminary results suggest that clinically useful information can be obtained by performing these assays on random urine specimens.

Estradiol↗
PubMed1978

Reconstruction of glutamine synthetase using computer averaging.

The axial projection of the glutamine synthetase molecule has been reconstructed from electron micrographs of a stained preparation by using a new method of correlation search and averaging. The average over 50 individual molecules appears as a radial pattern with sixfold symmetry. The handedness evident in the average is attributed to nonuniformity of the negative stain.

Bacillus↗
PubMed1977

Preparation and antigenic properties of 5alpha-dihydrotestosterone-11-(O-carboxymethyl) oxime-BSA conjugate.

The C-11 (O-carboxymethyl) oxime derivative of 5-alphadihydrotestosterone (5alphaDHT) has been prepared. Due to steric hindrance at C-11, a novel two step procedure was used to introduce the (O-carboxymethyl) oxime at this position. Condensation of this oxime to bovine serum albumin afforded a conjugate which produced anti-5alphaDHT sera inoculated rabbits. Apart from a 30% cross reaction with testosterone, the antisera was reasonably specific for 5alphaDHT.

Animals↗
PubMed1977

Structure of ribulose-1,5-bisphosphate carboxylase-oxygenase: Form III crystals.

A new crystal form (III) of tobacco leaf ribulosebisphosphate carboxylase [3-phospho-D-glycerate carboxy-lyase (dimerizing), EC 4.1.1.39] has been grown by dialysis procedures, and is suitable for structural studies at near atomic resolution. The crystals exhibit birefringence, grow as pseudo-regular rhombic dodecahedrons, and belong to the tetragonal space group P4(2)2(1)2 with a = b = 149 A, c = 138 A, and V = 3.04 x 10(6) A(3). Each unit cell contains two molecules, with two large and two small subunits per asymmetric unit. At low resolution (>10 A) the crystal structure is body centered belonging to space group 1422 with one large/small pair in the asymmetric unit. Thus, at low resolution the molecular symmetry is D(4), the highest possible symmetry for an oligomer of stoichiometry large(8)small(8). Form III crystals may be identical to crystalline inclusions found in chloroplasts.

Journal Article↗
PubMedDate not supplied

Three-dimensional reconstruction of icosahedral particles--the uncommon line.

The past few years have seen an explosion in the number of viral structures determined by icosahedral reconstruction from cryoelectron micrographs. The success of this work has depended upon a combination of the high-fidelity but low-contrast information contained in these images with efficient algorithms for determining particle orientation and three-dimensional structure. This review describes the principles behind the most commonly used method of reconstruction of the icosahedral particles and the method's implementation in an icosahedral reconstruction program suite.

Algorithms↗
PubMedDate not supplied

A model-based approach for determining orientations of biological macromolecules imaged by cryoelectron microscopy.

A polar Fourier transform (PFT) method is described that facilitates determination and refinement of orientations of individual biological macromolecules imaged with cryoelectron microscopy techniques. A three-dimensional density map serves as a high signal-to-noise model from which a PFT database of different views is generated and against which the PFTs of individual images are correlated. The PFT produces rotation-invariant data particularly well-suited for rapid and accurate determination of orientation parameters. The method relies on accurate knowledge of the center of symmetry and radial scale of both model and image data but is insensitive to the relative contrast and background values of these data. Density maps may be derived from a variety of sources such as computer-generated models, X-ray crystallographic structures, and three-dimensional reconstructions computed from images. The PFT technique has been particularly useful for the analysis of particles with icosahedral symmetry and could be adapted for the analysis of single particles of any symmetry for which a crude model exists or can be produced.

Capsid↗
PubMedDate not supplied

The Electron Microscopy Outreach Program: A Web-based resource for research and education.

We have developed a centralized World Wide Web (WWW)-based environment that serves as a resource of software tools and expertise for biological electron microscopy. A major focus is molecular electron microscopy, but the site also includes information and links on structural biology at all levels of resolution. This site serves to help integrate or link structural biology techniques in accordance with user needs. The WWW site, called the Electron Microscopy (EM) Outreach Program (URL: http://emoutreach.sdsc.edu), provides scientists with computational and educational tools for their research and edification. In particular, we have set up a centralized resource containing course notes, references, and links to image analysis and three-dimensional reconstruction software for investigators wanting to learn about EM techniques either within or outside of their fields of expertise.

Academies and Institutes↗