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P C Krijgsman

Publications and source records attributed to P C Krijgsman.

7 recordsLinked to original sources
PubMed1985

Natural heterogeneity of shape, infectivity and protein composition in an influenza A (H3N2) virus preparation.

Influenza A (X31) virus was purified over a zonal sucrose gradient. The resulting gradient fractions were examined by electron microscopy, HA and infectivity titrations and gel electrophoresis. The fractions containing a homogeneous suspension of spherical particles had the highest infectivity per amount of viral protein and a much higher HA:M ratio than the unfractionated preparation. These results explain differences in the proportions of HA and M protein we have reported elsewhere on monodisperse virus suspensions compared with earlier measurements on crude suspensions.

Animals↗
PubMed1983

Structure of the Top a-t component of alfalfa mosaic virus. A non-icosahedral virion.

Neutron-scattering in combination with quasi-elastic light-scattering and electron microscopy was used to derive a model for the capsid structure of the Top a-t component of alfalfa mosaic virus (AMV-Ta-t). In the electron microscope, AMV-Ta-t appears as an irregular ellipsoidal particle with apparent dimensions 275 (+/- 31) A X 225 (+/- 22) A. Assuming that the particles are monodisperse, model calculations show that the neutron-scattering data are best explained by an oblate ellipsoidal shape for the virion with external dimensions 284 A X 284 A X 216 A. Based on this result, and in combination with the known composition of the virion, it is suggested that the capsid structure could be based on a deltahedron with 52 pointgroup symmetry and comprising 120 subunits. Such a model would imply a greater deviation from equivalent subunit interactions than normally necessary in icosahedral capsids. The neutron and photon correlation data, however, do not allow us to rule out the possibility that Top a-t is a slightly polydisperse preparation of irregular prolate shapes with mean dimensions 312 A X 232 A X 232 A. Both possibilities support the concept of alfalfa mosaic virus coat protein being capable of a wide range of intersubunit interactions, this flexibility resulting in considerable polymorphism in capsid structures.

Capsid↗
PubMed1978

Characterization of alfalfa-mosaic-virus protein polymerization in the presence of nucleic acid.

The polymerization of alfalfa mosaic virus (AMV) protein in the presence of homologous nucleic acids and a number of other natural and synthetic nucleic acids was studied. The conditions for optimal assembly were found to be pH 6.0 and low ionic strength (I = 0.1 M) at room temperature, irrespective of the type of nucleic acid. The resulting nucleoprotein particles exhibited the same structural characteristics as the virus. This information emerged from optical diffraction and computer filtering of electron micrographs from the reconstituted particles. Irrespective of the type of nucleic acid present the polymerization of the protein resulting in a nucleoprotein particle is a cooperative process. Evidence for this was obtained by nitrocellulose filter binding assay, sodium dodecylsulphate/polyacrylamide gel electrophoresis, sedimentation velocity and electron microscopy of the reaction mixtures. The rates and efficiencies of reconstitution were of the same order of magnitude for a number of ribonucleic acids. Sedimentation data derived from AMV protein and AMV RNA mixtures suggested the existence of a specific nucleation product in the first stage of assembly. The results are discussed in terms of a tentative model of the assembly, in which at least two different steps (nucleation and elongation) can be distinguished, each characterized by an association constant.

Chemical Phenomena↗
PubMed1976

A study of the states of aggregation of alfalfa mosaic virus protein.

The states of aggregation of alfalfa mosaic virus (AMV) protein have been characterized by sedimentation velocity experiments and electron microscopy. The main association product is a spherical particle with an s value of about 30S. It is highly likely that the assembly of this particle starts with dimers of the 25000 molecular mass unit resulting in an icosahedral particle made of 30 dimers. No intermediate aggregation products have been detected. The clustering pattern of the protein in the cylindrical part of the AMV capsid favours the concept of dimers as the active assembling units.

Capsid↗