[Inclusion compounds of collagen (author's transl)]. / Kollagen-Einschlussverbindungen.

Small angle X-ray diagrams of collagen of rat tail treated with phospho tungstic acid or mercury chloride or cobalt- and uranyl-nitrate, osmiumoxide or hydroxy apatite show the same characteristic new reflections and reflection lines. The only remarkable difference exists between fibers treated under stress or relaxed. These experiments give new evidence for the paracrystallinity of collagen. More than 100 parallel aligned ca. 40 A thick octafibrils consist of 670 A long microparacrystals with 5 ca. 25 A thick soft segment layers. In these soft segments the holes of the octafibrils build up a lattice of vacancies with lattice cells of 38,5 x 35 x 135 A3 length. The above mentioned molecules penetrate from the lateral sides through the soft segments into these vacancies building up complexes with peptide groups of collagen. Under stress only a small amount of vacancies is occupied, statistically distributed over the vacancy-lattice, because the soft segments of the octafibrils are constricted. Without stress about 10 to 25% of the octafibrils within one paracrystal are filled up with sediments in the soft regions. With increasing precipitation finally 500 A long needles are formed of the inclusive material as detected by Höhling with the electron microscope in collagen of turkey tendon. The importance of the paracrystalline collagen model is emphasized to understand the biological process like the mineralisation of collagen and beta-keratin in organism or the activity of bone apatite in exchanging calcium ions.

Analysis of the crystal arrangement in collagen fibrils of mineralizing turkey tibia tendon.

Mineralized pieces of tendons from the tibio-tarsus of turkeys were (i) shock-frozen, freeze-dried, embedded and cut without staining, or (ii) fixed, embedded and stained after sectioning. Micrographs were taken with an electron microscope on longitudinally cut sections. The center-to-center distances of neighboring apatitic needles within collagen fibrils were measured. For shock-frozen and freeze-dried specimens, the average of these distances is 4.7 nm and the most frequent value 4.2 nm; for the fixed and stained specimens, 3.8 nm and 3.6 nm, respectively. Laser diffraction of the electron micrographs showed a dumbbell-like intensity pattern (two diffuse maxima of intensity on the equator, one on each side of the central spot), giving an average distance of about 6 nm. This value represents the upper range of the direct measurements. The measurements demonstrate that the arrangement of the collagen microfibrils is mainly preserved during mineralization. However, using laser diffraction, distances of 9-11 nm were also observed. Such large distances can also be demonstrated by X-ray diffraction on collagen fibrils stained under special conditons. this may indicate that special conditions of apatitic mineralization or staining may alter the arrangement of the microfibrils.

Structure of cerebrosides. II. Small angle X-ray diffraction study of cerasine.

Cerasine having a molecular weight of 800 differs chemically from phrenosine only in the hydroxyl group attached to the fatty acid tail which is replaced by a hydrogen atom. Nevertheless, remarkable differences between both cerebrosides are detected in the lamellae periodicities. In the range of 23--66 degrees C just one single (instead of two) structure with a similar subcell to the triclinic one component of phrenosine detected. Between 66 and 87 degrees C three new components (instead of one in phrenosine) appear. Two of the structures are similar to the two phrenosine-components at low temperature and the tilt angles of their chains with respect to the basal planes can explain the stabilizing capacity of the 201 and 301 netplanes of the paraffin-like subcells respectively. These lattice planes are parallely aligned to the surfaces of the lamellae. The long period of 58 A of component II cannot be explained in such a way. This period persists up to 105 degrees C and coexists from 87 degrees C with a new component showing a 40 A-periodicity, which cannot either be explained in the above manner. Paracrystalline distortions of the arrangement of the bilayers can be justified by orientational disorder of the galactose heads.

Isoenzymes of alkaline phosphatase in the serum of patients with cystic fibrosis.

In 36 children with cystic fibrosis (CF) the isoenzymes of alkaline phosphatase (AP) were determined microelectrophoretically in polyacrylamide- and starch-gel. The study was done to evaluate the clinical significance of these additional data for the diagnosis of liver involvement in DF. The results led to the following conclusions: 1. Serum activity of total AP is comparatively unsensitive "masking" alterations in the isoenzyme pattern contributing to the AP serum activity. 2. In 17 children resp. 47% bile-duct phosphatase was increased indicating a secretostasis while other marker enzymes of cholestasis were normal in part. 3. The activity of bone phosphatase in the serum showed a significant correlation to the degree of growth retardation in these patients. 4. Intestinal phosphatase was present in the serum of only one child with cirrhosis of the liver being an indicator for liver insufficiency. 5. Determination of AP isoenzymes in the serum may provide additional information about the organs involved for the physician in handling CF patients.

Small angle x-ray scattering of the thylakoid membranes of Rhodopseudomonas speroides in aqueous suspensions.

The diffraction patterns of particles which have the shape of hollow spheres, i.e. vesicles, can be satisfactorily analyzed by means of a new formula of Weick (1974). This formula is used for the small angle X-ray scattering analysis of aqueous suspensions of thylakoids of Rhodopseudomonas spheroides. Some essential results are: (a) The membrane has a rather asymmetric structure with one layer of low electron density at its inner side and two layers of high electron density near the outer surface of the thylakoids. (b) The distance of the electron density maxima of the latter two layers is 45 +/- 5 A. (c) Between the two maxima is a region of an electron density nearly equal to that of water. (d) The sequence of the peaks is - + 0 + with increasing radius. The peaks extend over an interval of 120 +/- 10 A. (e) The thylakoids are strikingly of the same size. Their diameters, if defined by the outmost layer, vary statistically by about 4% and have an average value of approximately 640 A.