Structural studies of organosulfur compounds. 4. Stereochemistry and conformational properties of .alpha.- and .beta.-2-methoxy-trans-hexahydrobenzoxathiane 4,4-dioxides

1979 ◽  
Vol 44 (14) ◽  
pp. 2580-2582 ◽  
Author(s):  
Dorothy Lee ◽  
John C. Keifer ◽  
Robert P. Rooney ◽  
Timothy B. Garner ◽  
Slayton A. Evans
Keyword(s):  
Organosulfur Compounds ◽  
Structural Studies ◽  
Conformational Properties ◽  
Beta 2

Structural studies of organosulfur compounds. 3. Stereochemistry and conformational distortions in trans-hexahydro-1,4-benzoxathiane S-oxides

1977 ◽  
Vol 42 (13) ◽  
pp. 2206-2211 ◽  
Author(s):  
Donna M. Frieze ◽  
Philip F. Hughes ◽  
Robert L. Merrill ◽  
Slayton A. Evans
Keyword(s):  
Organosulfur Compounds ◽  
Structural Studies ◽  
In Trans

Structural studies of organosulfur compounds. 2. Conformational analysis of 2-methoxy-trans-hexahydro-1,4-benzoxathianes

1977 ◽  
Vol 42 (3) ◽  
pp. 438-441 ◽  
Author(s):  
Slayton A. Evans ◽  
Barry Goldsmith ◽  
Robert L. Merrill ◽  
Robert E. Williams
Keyword(s):  
Conformational Analysis ◽  
Organosulfur Compounds ◽  
Structural Studies

Detection of two abnormal hemoglobins, Hb Manitoba and Hb G-Coushatta, during analysis of glycohemoglobin (A1c) by high-performance liquid chromatography

1991 ◽  
Vol 37 (8) ◽  
pp. 1456-1459 ◽  
Author(s):  
S C Wong ◽  
M Tesanovic ◽  
M C Poon
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Diabetic Patients ◽  
Structural Studies ◽  
Blood Samples ◽  
Hb A1c ◽  
Beta 2

Abstract This report concerns the detection of two abnormal hemoglobins (Hb), Hb Manitoba and Hb G Coushatta, during analysis for glycohemoglobin (Hb A1c). Blood samples from two diabetic patients, analyzed for Hb A1c by HPLC, were found to contain additional Hb peaks. The presence of an abnormal Hb was confirmed in both instances by hemoglobinopathy studies. Structural studies determined the two Hb variants to be Hb Manitoba (alpha 2 102 Ser----Arg beta 2) and Hb G-Coushatta (alpha 2 beta 2 22 Glu----Ala). The significance of the presence of an abnormal Hb in Hb A1c analysis is discussed.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Structural Studies on Mitotic Spindle Fibres

1978 ◽  
Vol 36 (3) ◽  
pp. 615-626
Author(s):  
J.R. Mcintosh
Keyword(s):  
Chemical Composition ◽  
Mitotic Spindle ◽  
Structural Studies ◽  
Mitotic Apparatus ◽  
Chemical Studies ◽  
Medical Interest ◽  
Spindle Fibres

The mitotic apparatus is a structure of obvious biological and medical interest, but it has proved to be a difficult cellular machine to understand. The chemical composition of the spindle is only slightly elucidated, largely because of the difficulties in preparing useful isolates of the structure. Chemical studies of the mitotic spindle have been reviewed elsewhere (Mcintosh, 1977), and will not be discussed further here. One would think that structural studies on the mitotic apparatus (MA) in situ would be straightforward, but even with this approach there is some disagreement in the results obtained with various methods and by different investigators. In this paper I will review briefly the approaches which have been used in structural studies of the MA, pointing out the strengths and problems of each approach. I will summarize the principal findings of the different methods, and identify what seem to be fruitful avenues for further work.

Image registration with a computer driven S.T.E.M.

1978 ◽  
Vol 36 (1) ◽  
pp. 98-99
Author(s):  
A.M.H. Schepman ◽  
J.A.P. van der Voort ◽  
J.E. Mellema
Keyword(s):  
Spot Size ◽  
Scanning Transmission Electron Microscope ◽  
Small Computer ◽  
Structural Studies ◽  
Area Of Interest ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Specimen Area ◽  
On Line ◽  
Minimum Distances

A Scanning Transmission Electron Microscope (STEM) was coupled to a small computer. The system (see Fig. 1) has been built using a Philips EM400, equipped with a scanning attachment and a DEC PDP11/34 computer with 34K memory. The gun (Fig. 2) consists of a continuously renewed tip of radius 0.2 to 0.4 μm of a tungsten wire heated just below its melting point by a focussed laser beam (1). On-line operation procedures were developped aiming at the reduction of the amount of radiation of the specimen area of interest, while selecting the various imaging parameters and upon registration of the information content. Whereas the theoretical limiting spot size is 0.75 nm (2), routine resolution checks showed minimum distances in the order 1.2 to 1.5 nm between corresponding intensity maxima in successive scans. This value is sufficient for structural studies of regular biological material to test the performance of STEM over high resolution CTEM.

The Fine Structure of Phloem Cells

1985 ◽  
Vol 43 ◽  
pp. 632-635
Author(s):  
James Cronshaw
Keyword(s):  
Structural Studies ◽  
High Concentration ◽  
Long Distance ◽  
Phloem Tissue ◽  
Sieve Elements ◽  
Long Distance Transport ◽  
P Protein ◽  
Companion Cells ◽  
Electron Microscopical ◽  
Distance Transport

Long distance transport in plants takes place in phloem tissue which has characteristic cells, the sieve elements. At maturity these cells have sieve areas in their end walls with specialized perforations. They are associated with companion cells, parenchyma cells, and in some species, with transfer cells. The protoplast of the functioning sieve element contains a high concentration of sugar, and consequently a high hydrostatic pressure, which makes it extremely difficult to fix mature sieve elements for electron microscopical observation without the formation of surge artifacts. Despite many structural studies which have attempted to prevent surge artifacts, several features of mature sieve elements, such as the distribution of P-protein and the nature of the contents of the sieve area pores, remain controversial.

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