CBETA: First Multipass Superconducting Linear Accelerator with Energy Recovery.

Energy recovery has been achieved in a multipass linear accelerator, demonstrating a technology for more compact particle accelerators operating at higher currents and reduced energy consumption. Energy delivered to the beam during the first four passes through the accelerating structure was recovered during four subsequent decelerating passes. High-energy efficiency was achieved by the use of superconducting accelerating cavities and permanent magnets. The fixed-field alternating-gradient optical system used for the return loop successfully transported electron bunches of 42, 78, 114, and 150 MeV in a common vacuum chamber. This new kind of accelerator, an eight-pass energy recovery linac, has the potential to accelerate much higher current than existing linear accelerators while maintaining small beam dimensions and consuming much less energy per electron.

Separation of native types I and III collagens and denatured chains by reverse-phase high-performance liquid chromatography.

A simple and effective high-performance-liquid-chromatography system has been developed for the separation of the native forms of Types I and III collagens. This separation is achieved on a commercially available 330-A-pore-size C18 reverse-phase support using a solvent system consisting of ammonium bicarbonate (0.05 M) and trifluoroacetic acid (0.4%) with tetrahydrofuran as the eluting solvent. This simple system can also be applied to the separation of mixtures of the denatured chains of both collagen types.

A new rapid method for the identification of reducible collagen cross-links in small tissue samples.

A normal-phase high-pressure liquid-chromatography system was used with amino-propyl-bonded silica as the column packing in order to resolve amino acids, reduced amino acid derivatives and reduced cross-links of collagen. The method utilized a solvent system comprising acetonitrile and 10 mM-potassium phosphate buffer, pH 4.3, as described by Schuster [(1980) Anal. Chem. 52, 617-620]. With modifications to the original gradient elution it was possible to resolve fully the radiolabelled components of reduced collagen in one run of less than 80 min. The method is very sensitive, and small biopsy samples can readily be investigated. Although solute retention times gradually decreased with repeated use, little loss of resolution of the reducible cross-links of collagen occurred during a 30-day trial period.

Investigation of the parameters for reversed-phase high-performance liquid chromatography of collagen types I and III.

A detailed study was carried out on the behaviour of collagen and its subcomponents on large pore size reversed-phase high-performance liquid chromatographic columns. Investigation of laboratory-prepared C18 and CN 50-nm pore size supports using a simple solvent system showed that heat-denatured collagen chains could be retained and resolved and that the C18 packing had a greater selective capacity. However, because of inconsistencies in the chromatography obtained using laboratory-prepared supports commercial 33-nm pore size packings were subsequently studied with both pyridine-based and trifluoroacetic acid-based solvent systems. An optimised solvent was defined and used to check the resolving capacity of both C18 and CN commercial columns. These studies led to the description and interpretation of the effects of pH, counter-ion concentration, solvent strength, type of support and molecular weight of protein solutes on the chromatographic behaviour of this large protein and its CNBr peptides. An explanation of the major forces acting to bring about retention and resolution is presented and suggestions are made for the application of this methodology to other proteins.

An extremely thermostable extracellular proteinase from a strain of the archaebacterium Desulfurococcus growing at 88 degrees C.

An organism growing at 88 degrees C that closely resembles Desulfurococcus mucosus produced a single extracellular proteinase. We have purified this enzyme and carried out a preliminary characterization. The proteinase, which is a serine-type enzyme, had a molecular mass of 52,000 Da by SDS/polyacrylamide-gel electrophoresis, but only 10,000-13,000 Da by gel-permeation chromatography. Molecular mass values from sucrose-gradient centrifugation were of the same order as those from SDS/polyacrylamide-gel electrophoresis. It had an isoelectric point of 8.7, and was inhibited by di-isopropyl phosphorofluoridate, phenylmethanesulphonyl fluoride and chymostatin. Substrate-specificity studies suggested a possible preference for hydrophobic residues on the C-terminal side of the splitting point. The thermostability of this enzyme is probably greater than any other reported proteinase (t1/2 at 95 degrees C, 70-90 min; t1/2 at 105 degrees C, 8-9 min). Ca2+ chelation does not appear to be implicated in stabilization of the protein structure. The stability of the Desulfurococcus proteinase was not greatly affected by the presence of reducing reagents (e.g. dithiothreitol), some chaotropic agents (e.g. NaSCN) and some detergents, but activity was lost rapidly at 95 degrees C in the presence of the oxidizing agent NaBO3. Proteolytic activity was readily detected at temperatures up to and including 125 degrees C, although denaturation was very rapid above 115 degrees C. A number of Figures supporting some of the findings reported in this paper have been deposited in supplement SUP 50137 (14 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies may be obtained on the terms indicated in Biochem. J. (1987) 241, 5.

Type I and III collagen content and fibre distribution in normal human skin during ageing.

The content of type I and III collagen in normal human skin from subjects of different ages was studied by means of a new high performance liquid chromatography method and by SDS-polyacrylamide gel electrophoresis and scanning electron microscopy. The ratio of types I and III collagen in covered skin remained constant throughout childhood and young adult life and the proportion of type III was shown to be the same as previously reported. However, in the elderly, the proportion of type III collagen in the dermis increased to a variable degree. Scanning electron microscopic examination showed a decrease in the number of collagen fibre bundles with age. Average bundle width varied significantly with age. These results may reflect an impaired synthesis of type I collagen in aged skin.