Sulfur oxidation, genetics

Further work at EniTecnologies was conducted with Rhodococcus strains. Rhodococ-cus was selected for its metabolical versatility, easy availability in soils and water, and remarkable solvent tolerance. Its capabilities for catalyzing diverse transformation reactions of crude oils, such as sulfur removal, alkanes and aromatics oxidation and catabolism caught their attention. Hence, genetic tools for the engineering of Rhodococcus strains have been applied to improve its biotransformation performance and its tolerance to certain common contaminants of the crude oil, such as cadmium. The development of active biomolecules led to the isolation and characterization of plasmid vectors and promoters. Strains have been constructed in which the careful over-expression of selected components of the desulfurization pathway leads to the enhancement of the sulfur removal activity in model systems. Rhodococcus, Gordona, and Nocardia were transformed in this way trying to improve their catalytic performance in BDS. In a... 

Melanin granules are secreted by melanocytes in the hair papilla and distributed to keratin in the hair cortex and inner layers of the hair sheath during normal development. Melanogenesis is subject to hormonal control and has been the focus of intensive genetic studies. Two main forms of melanin exist in human skin—eumelanin and phaeomelanin, both of which are derived from tyrosine through the action of tyrosinase (a cupro-enzyme) and possibly other key enzymes (with nickel, chromium, iron, and manganese as cofactors). Tyrosine is converted to dihydroxyphenylalanine and, via a series of intermediate steps, to indole-5,6-quinone, which polymerizes to eumelanin. Phaeomelanins are produced by a similar mechanism but with the incorporation of sulfur (as cysteine) by a nonenzymatic step in the oxidation process. 

Agronomic and other cultivated species would not be acutely impaired if future oxidant and sulfur dioxide levels remain as they are today. There appears to be sufficient genetic resistance to foliar injury within cultivated species that cultivars which are resistant to existing... 

A major development in the definition of the constitution of Moco was the recognition that an oxidized, inactive, form of this cofactor has the fluorescence properties characteristic of a pterin. Further studies indicated that the fluorescent materia was derived from a novel, sulfur-containing reduced pterin substituted at the C-6 position.Subsequently, a metabolic relationship was established between Moco and urothione, since persons genetically deficient in Moco are unique in having no detectable urothione in their urine. This metabolic relationship, and the chemical reactions of the cofactor, formed the basis from which Johnson and Rajagopalan proposed a structure (Figure 17) for Moco. ... 

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