J. Appl. Cryst.の発刊に際して

I read this book the same weekend that the Packers took on the Rams, and the experience of the latter event, obviously, colored my judgment. Although I abhor anything that smacks of being a handbook (like, \"How to Earn a Merit Badge in Neurosurgery\") because too many volumes in biomedical science already evince a boyscout-like approach, I must confess that parts of this volume are fast, scholarly, and significant, with certain reservations. I like parts of this well-illustrated book because Dr. Sj6strand, without so stating, develops certain subjects on technique in relation to the acquisition of judgment and sophistication. And this is important! So, given that the author (like all of us) is somewhat deficient in some areas, and biased in others, the book is still valuable if the uninitiated reader swallows it in a general fashion, realizing full well that what will be required from the reader is a modulation to fit his vision, propreception, adaptation and response, and the kind of problem he is undertaking. A major deficiency of this book is revealed by comparison of its use of physics and of chemistry to provide understanding and background for the application of high resolution electron microscopy to problems in biology. Since the volume is keyed to high resolution electron microscopy, which is a sophisticated form of structural analysis, but really morphology in a modern guise, the physical and mechanical background of The instrument and its ancillary tools are simply and well presented. The potential use of chemical or cytochemical information as it relates to biological fine structure , however, is quite deficient. I wonder when even sophisticated morphol-ogists will consider fixation a reaction and not a technique; only then will the fundamentals become self-evident and predictable and this sine qua flon will become less mystical. Staining reactions (the most inadequate chapter) ought to be something more than a technique to selectively enhance contrast of morphological elements; it ought to give the structural addresses of some of the chemical residents of cell components. Is it pertinent that auto-radiography gets singled out for more complete coverage than other significant aspects of cytochemistry by a high resolution microscopist, when it has a built-in minimal error of 1,000 A in standard practice? I don't mean to blind-side (in strict football terminology) Dr. Sj6strand's efforts for what is \"routinely used in our laboratory\"; what is done is usually well done. It's just that …

Methods in Enzymology.

Neutron small-angle scattering provides a new tool for investigation of the structure of biological particles. The method is derived from X-ray small-angle scattering. The very large difference between the scattering amplitude of neutrons by hydrogen and deuterium gives the basis of this method, which is explained with reference to the X-ray technique, as both methods have a complementary aspect. Experimental results so far obtained are reviewed, with an emphasis on biological structures composed of two kinds of molecules, such as ribosomes, nucleosomes and viruses.

https://iopscience.iop.org/article/10.1088/0034-4885/39/10/001/pdf

The study of biological structures by neutron scattering from solution

Fouling strategies and the cleaning system of NF membranes and factors affecting cleaning efficiency

Amino acid sequences, carbohydrate compositions and residue volumes are used to compare critically calculations of partial specific volumes v, neutron scattering matchpoints and 280-nm absorption coefficients with experimental v values for proteins and glycoproteins. The v values that are obtained from amino acid densitometry underestimate experimental v values by 0.01-0.02 ml/g while the v values from crystallographic volumes overestimate the experimental v values by 0.04-0.05 ml/g. An intermediate consensus volume set of amino-acid-residue volumes is proposed in order to predict experimental v values using sequence information. The method is extended to carbohydrates and glycoproteins. Neutron scattering matchpoints can be calculated from crystallographic residue volumes on the basis of the non-exchange of 10% of the main-chain NH protons. Crystallographic results on protein-bound water are used to account for the experimental values of v and matchpoints. Finally, 280-nm absorption coefficients, A1%, 1 cm 280, of 5-27 are found to be well predicted by the Wetlaufer procedure based on the totals of Trp, Tyr and Cys residues. Average errors are +/- 0.7, and the experimental A(1%,1cm)280 values can be larger than the predicted values by 3%.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1986.tb09653.x

Protein volumes and hydration effects. The calculations of partial specific volumes, neutron scattering matchpoints and 280-nm absorption coefficients for proteins and glycoproteins from amino acid sequences.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/0014-5793%2878%2980817-5

Small-angle X-ray scattering study of the proteins S1, S8, S15, S16, S20 from Escherichia coli ribosomes.

Humic acids, which are present in soil and all natural water systems, play a central part in the biosphere since they are one of the key components in the release of nutrients to the plant kingdom (reviews in [1, 2]). Numerous attempts have been made to gain an understanding of the size and shape of humic acid molecules but, as yet, their structures are not known in detail [3, 4]. Recently, it was shown that small-angle neutron scattering from solutions of humic acids obeys a power law almost over two orders of magnitude in length scale of the scattering vector, Q, [5 -7] , indicating that the structure is fractal [8, 9]. In this range the structure is scale-invariant in the sense that it appears similar after magnification. This is valid for 1/~<_Q<_l/a, where ~ is the upper cut-off length of the cluster, and a the characteristic dimension of each individual scatterer. For the humic acid clusters, the value of ~ varied from 20 to 100nm, depending on the method of preparation and source [5-7] . However, the fractal dimension, D, remained essentially constant at D = 2.35_+0.05 [5-7] . (It is defined as the power with which the mass, M, of the aggregate increases with increasing radius, r : M--rD; when D is close to 3 the particles are very dense, while a value close to 1 indicates a loosely connected network.) Within our measured range (I/Q_>0.7 nm), we observed no cut-off corresponding to the length of a monomer [7]. Thus, our data would be consistent with the existence of relatively small scattering units similar to the building blocks (aromatic residues) of the network structure reported in [3], rather than with larger units, such as, for instance, the network structure itself ( M = 6651) [3]; however, a final conclusion as to whether or not such large repetitive units are involved cannot be reached on the basis of neutron scattering data alone (see the discussion in [7], p. 274).

Direct observation of humic acid clusters, a nonequilibrium system with a fractal structure

The solution shapes of IgG3 immunoglobulin and its Fch and Fc fragments. A small-angle X-ray scattering study.

The growth of humic acids, prepared by a gentle method from two different kinds of soils (I and II), has been studied using small-angle neutron scattering at an acidity corresponding to pH 5.0 and 0.10 M ionic strength (NaCl). Humic acids aggregate either to large clusters with a fractal dimension of 2.3 and an average diameter of 1720 A (I) or to clusters with an average diameter of 700 A (II). After storage for 2 days at 4 degrees C, the latter aggregates (II) formed a gel. In a step toward gelation, we observed cluster-cluster interaction from the neutron-scattering data in the form of a correlation peak. These differences in size can be explained by assuming that the smaller particles (II) are trapped into a nonequilibrium state characterized by the temperature-solvent condition. The importance of a humic acid gel network for the conservation of water and nutrients in the environment is discussed.

The growth of fractal humic acids: cluster correlation and gel formation.

/pdf/inert-copper-ion-complexes-formed-by-humic-acids-33r5g5aopx.pdf

Ragnar Österberg

Papers

Small-angle X-ray scattering study of the proteins S1, S8, S15, S16, S20 from Escherichia coli ribosomes.

Direct observation of humic acid clusters, a nonequilibrium system with a fractal structure

The solution shapes of IgG3 immunoglobulin and its Fch and Fc fragments. A small-angle X-ray scattering study.

The growth of fractal humic acids: cluster correlation and gel formation.

Inert Copper Ion Complexes Formed by Humic Acids.