Study of the (S)-hydroxynitrile lyase from Hevea brasiliensis: mechanistic implications.

Investigations of the (S)-selective hydroxynitrile lyase from Hevea brasiliensis were performed by electrospray mass spectroscopy, (1)H-NMR and with an enzyme activity assay. For the trans-cyanohydrin reaction (transcyanation) a two step reaction could be established. The results furthermore indicate a fast deactivation of the enzyme at low pH and a strong substrate dependence of its stability. They rule out an enzyme-HCN complex or a covalently bound carbonyl compound. Therefore the earlier postulated reaction intermediate as well as the proposed action of the catalytic triad have to be reevaluated. The calculated molecular mass could be confirmed by mass spectroscopy.     

Studies on Fusarium-Gladiolus Interactions

Using standardized conditions, 65 genotypes of Gladiolus were screened for Fusarium resistance. High levels were found in 'large-flowered types, Primulinus hybrids, G. callianthus, G. garnierii , and G. dalenii. Some accessions of G. dalenii exhibited no disease symptoms when inoculated with two standard test isolates. No resistance was found in 'small-flowered' types. To estimate race-specifity of the resistance, eight highly resistant Gladiolus genotypes were tested in an in vitro test against 43 isolates of F. oxysporum f.sp. gladioli. Two isolates were able to partially infect the G. dalenii accessions and this was confirmed using whole plants. Implications for resistance breeding are discussed.     

In situ product recovery (ISPR) by crystallization: basic principles, design, and potential applications in whole-cell biocatalysis

The removal of inhibiting or degrading product from a bioreactor as soon as the product is formed is an important issue in industrial bioprocess development. In this review, the potential of crystallization as an in situ product removal (ISPR) technique for the biocatalytic production of crystalline compounds is discussed. The emphasis of this review is on the current status of crystalline product formation by metabolically active cells for application in fine-chemicals production. Examples of relevant biocatalytic conversions are summarized, and some basic process options are discussed. Furthermore, a case study is presented in which two conceptual process designs are compared. In one process, product formation and crystallization are integrated by applying ISPR, whereas a second, nonintegrated process is based on a known conventional process equivalent for the production of 6R-dihydro-oxoisophorone. The comparison indicates that employing ISPR leads to significant advantages over the nonintegrated case in terms of increased productivity and yield with a corresponding decrease in the number of downstream processing steps, as well as in the quantity of waste streams. This leads to an economically more interesting process alternative. Finally, a general outlook on the various research aspects of ISPR by crystallization is given.     

Cytokine gene polymorphisms and atopic disease in two European cohorts. (ECRHS-Basel and SAPALDIA)

Background

Avoidance of allergens is still recommended as the first and best way to prevent allergic illnesses and their comorbid diseases. Despite a variety of attempts there has been very limited success in the area of environmental control of allergic disease. Our objective was to identify a non-invasive, non-pharmacological method to reduce indoor allergen loads in atopic persons' homes and public environments. We employed a novel in vivo approach to examine the possibility of using aluminum sulfate to control environmental allergens.

Methods

Fifty skin test reactive patients were simultaneously skin tested with conventional test materials and the actions of the protein/glycoprotein modifier, aluminum sulfate. Common allergens, dog, cat, dust mite, Alternaria, and cockroach were used in the study.

Results

Skin test reactivity was significantly reduced by the modifier aluminum sulfate. Our studies demonstrate that the effects of histamine were not affected by the presence of aluminum sulfate. In fact, skin test reactivity was reduced independent of whether aluminum sulfate was present in the allergen test material or removed prior to testing, indicating that the allergens had in some way been inactivated.

Conclusion

Aluminum sulfate was found to reduce the in vivo allergic reaction cascade induced by skin testing with common allergens. The exact mechanism is not clear but appears to involve the alteration of IgE-binding epitopes on the allergen. Our results indicate that it may be possible to diminish the allergenicity of an environment by application of the active agent aluminum sulfate, thus producing environmental control without complete removal of the allergen.