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Alexander McPherson
Penn State Milton S. Hershey Medical Center
9Publications
4H-index
222Citations
Publications 9
Newest
#1Kirk H. Shelley (Penn State Milton S. Hershey Medical Center)H-Index: 20
#2Alexander McPherson (Penn State Milton S. Hershey Medical Center)H-Index: 4
SUMMARY Microcrystals of B. subtilis α-amylase have been negatively stained and examined by electron microscopy. The micrographs were then subjected to spatial filtering and averaging using a Fourier transform procedure programmed for a mini computer. From these ‘enhanced’ images refined crystallographic parameters were obtained and a model for the packing of the asymmetric units within the crystal was derived. In addition, these parameters obtained from electron microscopy are compared with tho...
#1Kirk H. Shelley (Penn State Milton S. Hershey Medical Center)H-Index: 20
#2Alexander McPherson (Penn State Milton S. Hershey Medical Center)H-Index: 4
Abstract The lectin from the seeds of Abrus precatorius has been crystallized and the crystals subjected to study by X-ray diffraction and electron microscopy. Three closely related crystal forms were obtained, of orthorhombic space group P 2 1 2 1 2 1 with a = 138 A , b = 142 A , and c = 173 A , of tetragonal space group P 4 1 2 1 2 with a = b = 136 A , c = 176 A , and a twinned intermediate of the first two. From electron microscopy and two-dimensional spatial filtering of electron micrographs...
#1Alexander McPherson (Penn State Milton S. Hershey Medical Center)H-Index: 4
#2Harold B. White (UD: University of Delaware)H-Index: 21
Abstract Single crystals of chicken muscle glycerol 3-phosphate dehydrogenase have been obtained which are suitable for a high resolution structure analysis. The crystals are triclinic with smallest cell dimensions of a=58.9 A b=54.5 A c=58.5 A α =91° β =95° δ =89° but show a substantial degree of pseudo symmetry which indicates the presence of at least an approximate and possibly exact dyad axis relating the two subunits in the asymmetric unit.
#1Kirk H. Shelley (Penn State Milton S. Hershey Medical Center)H-Index: 20
#2Barry S. Hillman (Penn State Milton S. Hershey Medical Center)H-Index: 2
Last.Alexander McPherson (Penn State Milton S. Hershey Medical Center)H-Index: 4
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Abstract Images of the α-amylase molecule from pig pancreas have been obtained in two projections by the application of spatial filtering techniques to electron micrographs of negatively stained microcrystals of the enzyme. The Fourier filtering was performed on a PPD 11 40 digital computer after microdensitometry on an Optronics P-1000 photoscan system. The set of procedures and programs we employed are described herein. We compared these images with equivalent images obtained by three-dimensio...
#1Paula M.D. Fitzgerald (Penn State Milton S. Hershey Medical Center)H-Index: 1
#2Paul J. Stankiewicz (Penn State Milton S. Hershey Medical Center)H-Index: 2
Last.Alexander McPherson (Penn State Milton S. Hershey Medical Center)H-Index: 4
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Abstract Three-dimensional structure analyses of two polysaccharide degrading enzymes, α-amylase and α-mannosidase, though not yet complete, reveal that both enzymes are structural tandem duplicates and that the two similar domains within each are related by a dyad axis of symmetry.
#1Alexander McPherson (Penn State Milton S. Hershey Medical Center)H-Index: 4
#2Shirley Hoover (Penn State Milton S. Hershey Medical Center)H-Index: 1
Abstract The lectin-mitogens from Hura crepitans and Robinia pseudacaccia have been purified by affinity chromatography and compared to that from Abrus precatorius by sodium lauryl sulfate gel electrophoresis. Robinia lectin is quite similar to that from Abrus precatorius in that it consists of two distinct polypeptide chains of 32,000 and 30,000 daltons but unlike abrus lectin the chains are not joined by disulphide bonds. Hura lectin is composed of only a single polypeptide chain which migrate...
#1Alexander McPherson (Penn State Milton S. Hershey Medical Center)H-Index: 4
#2Frances A. Jurnak (Penn State Milton S. Hershey Medical Center)
#1Alexander McPherson (Penn State Milton S. Hershey Medical Center)H-Index: 4
#2Roderick Spencer (MIT: Massachusetts Institute of Technology)H-Index: 1
Abstract The plant seed protein canavalin has been crystallized alter trypsinization by using vapor diffusion to effect isoelectric precipitation. The space groups and cell dimensions are R3 with a = 81.3 A , γ = 111 ° and having extremely high R 32 pseudo symmetry, P6 3 with a = 126 A and c = 51 A , C222 1 , with a = 136 A , b = 152 A , and c = 131 A . X-ray data combined with electron microscopy suggests the molecule to be composed of six identical subunits. each of 18,500 daltons, arranged in...
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