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At least 109 records · Page 6Linked to original sources
PubMed1986

Mössbauer spectroscopy of haemoglobins. Study of the relationship of Fe2+ electronic and molecular structure of the active site.

Human normal, adult and foetal oxyhaemoglobins and oxyhaemoglobins from leukaemic patients were studied, by Mössbauer spectroscopy. The estimations of quadrupole splitting delta EQ and isomer shift delta allow one to distinguish between adult, foetal and leukaemic oxyhaemoglobins. The differences in the Fe2+ electronic structure and active site molecular structure of foetal and leukaemic oxyhaemoglobins were analyzed.

Allosteric Regulation↗
PubMed1983

Current status of the molecular structure and function of the plasma sex steroid-binding protein (SBP).

Purification and characterization of the sex steroid-binding protein (SBP) from human, macaque, baboon, and rabbit sera indicate that the protein is composed of two polypeptide chains which associate noncovalently to yield a native structure having molecular weight distributions of about 88,000 for primate SBPs, and 80,000 for rabbit SBP. The subunit molecular weight distributions are 44,000 for human SBP, 47,000 for macaque and baboon SBP's, and 40,000 for rabbit SBP. Isoelectric focusing show extensive microheterogeneity for all four SBPs. The patterns appear to be unique for each species and reveal the presence of at least twelve bands of different colour intensity reflecting a specific spectrum of active SBP molecules. The existence of the large number of dimeric forms of SBP arises through the combination of many variants of the same two subunits containing different amounts and types of carbohydrate sidechains. Physiological studies on the intravenous infusion of pure rhesus SBP, human SBP, and purified monospecific SBP-antibodies into the rhesus reveal an inverse relationship between SBP and the metabolic clearance rate of testosterone. The effect is complex and depends on the concentration of SBP, albumin, and testosterone which in turn influences the distribution of testosterone between albumin and SBP.

Animals↗
PubMed2005

Tangible interfaces for structural molecular biology.

The evolving technology of computer autofabrication makes it possible to produce physical models for complex biological molecules and assemblies. Augmented reality has recently developed as a computer interface technology that enables the mixing of real-world objects and computer-generated graphics. We report an application that demonstrates the use of autofabricated tangible models and augmented reality for research and communication in molecular biology. We have extended our molecular modeling environment, PMV, to support the fabrication of a wide variety of physical molecular models, and have adapted an augmented reality system to allow virtual 3D representations to be overlaid onto the tangible molecular models. Users can easily change the overlaid information, switching between different representations of the molecule, displays of molecular properties, or dynamic information. The physical models provide a powerful, intuitive interface for manipulating the computer models, streamlining the interface between human intent, the physical model, and the computational activity.

Computer-Aided Design↗
PubMed2002

Studies on the effect of electron beam radiation on the molecular structure of ultra-high molecular weight polyethylene under the influence of alpha-tocopherol with respect to its application in medical implants.

Ultra-high molecular weight polyethylene (UHMW-PE) is being used successfully for articulating surfaces in joint endoprostheses, especially for cups of total hip endoprostheses. Sintered specimens containing various amounts of alpha-tocopherol (vitamin E) as a biocompatible stabilizer, were irradiated in nitrogen atmosphere as well as in air with various dosages of electron beam radiation. Size exclusion chromatography (SEC) was used to analyze the soluble fractions of the UHMW-PE samples according to their molecular weight distribution prior to and after irradiation. In nitrogen atmosphere the radiation-induced crosslinking showed to be dependent on the added amount of alpha-tocopherol in the sintered specimens. With an increasing content of alpha-tocopherol, the stabilizer acted as a scavenger for free radicals. Thus, the crosslinking was more and more hindered. The same effect was observed on the samples irradiated in air, where, in addition to the crosslinking process, oxidative molecular degradation occurred. The highest extent of crosslinked material was yielded with unstabilized samples in nitrogen atmosphere.

Journal Article↗
PubMed1980

The molecular structure of low and high molecular weight levans synthesized by levansucrase.

The levan synthesized by Bacillus subtilis levansucrase in the presence of alcohols was of only high molecular weight, while in solutions of high ionic strength only low molecular weight (MW) levan was produced. The addition of low MW levan to the enzyme reaction mixture at low ionic strength stimulated synthesis of a high MW levan, but the levan added was not incorporated into this high MW levan. Methylation analysis revealed that low MW levans contained glucose, which was isolated as 2,3,46-tetra-O-methyl alditol acetate showing that the glucose units existed as terminal residues. The molecular weight of levan estimated on the basis of glucose content coincided with that determined by the gel filtration method. Methylation analysis also revealed that the number of fructose residues of the linear fraction linked by leads to 6(F)2 leads to type bonds was 22 for levan with a molecular weight of (8.4(-22)) x 10(3), while it was 11 for that of 2,000 x 10(3). The number of (formula: see text) type branched residues increased with increase in the molecular weight of the levan synthesized.

Bacillus subtilis↗