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Biomedical subjects

H S Forrest

Publications and source records attributed to H S Forrest.

At least 19 recordsLinked to original sources
PubMed1985

Replacement of methoxatin by 4,7-phenanthroline-5,6-dione and the inability of other phenanthroline quinones, as well as 7,9-di-decarboxy methoxatin, to serve as cofactors for the methoxatin-requiring glucose dehydrogenase of Acinetobacter calcoaceticus.

Glucose dehydrogenase from A. calcoaceticus has been dissociated into apoenzyme and methoxatin coenzyme, and enzyme activity restored by replacing coenzyme with 4,7-phenanthroline-5,6-dione but not with 1,10- nor 1,7-phenanthroline-5,6-diones nor with 7,9-decarboxy methoxatin.

Acinetobacter↗
PubMed1981

Crystallization of a derivative of a new coenzyme, methoxatin.

A new compound, derived from a parent compound to which we have given the trivial name, methoxatin, has been isolated from a methanol-oxidizing bacterium, and crystallized. Its chemical structure was determined by X-ray crystallography. Methoxatin is implicated as a coenzyme in the oxidation of substrate alcohols. This report describes the purification and crystallization of the derivative, acetonyl methoxatin.

Chemical Phenomena↗
PubMed1981

Terminal synthesis of xanthommatin in Drosophila melanogaster. IV. Enzymatic and nonenzymatic catalysis.

Nonenzymatic and enzymatic catalysis of the oxidation of 3-hydroxykynurenine (and 3-hydroxyanthranilic acid) has been studied and characterized in Drosophila extracts, clearing up some of the confusion surrounding the synthesis of the brown eye pigment, xanthommatin. The genetic basis of the terminal steps in pigment synthesis remains obscure, since all mutants tested have full synthetase activity.

Amino Acids↗
PubMed1979

Drosophila melanogaster lacks eye-pigment binding proteins.

Drosophila melanogaster contains no detectable eye-pigment binding proteins, and the previous evidence for the presence of such protein in the cecropia moth is probably not valid. The major brown pigment of Drosophila (and of Cecropia), dihydroxanthommatin, behaves as a high molecular weight compound in Sephadex chromatography, thus leading to false conclusions.

Animals↗
PubMed1974

Substrate specificity of the purified primary alcohol dehydrogenases from methanol-oxidizing bacteria.

Hyphomicrobium strain WC, Pseudomonas strain TP-1, and Pseudomonas strain W1 are capable of growth on methanol as the sole source of carbon and energy. Methanol-grown cells of each organism contain a primary alcohol dehydrogenase that has been purified to homogeneity. Each enzyme has a molecular weight of 120,000 and shows an in vitro requirement for phenazine methosulfate and ammonium ions for enzymatic activity. Normal aliphatic alcohols are oxidized rapidly by each enzyme. The presence of a methyl group on the carbon atom adjacent to the primary alcohol group lowers the enzymatic activity. This effect is reduced as the methyl substituent is moved further away from the hydroxyl group. The effect of other substituents on enzymatic activity is reported. Methanol, formaldehyde, and to a limited extent acetaldehyde are oxidized by the primary alcohol dehydrogenases. Higher aldehydes are not oxidized. A possible explanation for this specificity, with regard to aldehydes, is presented in terms of degree of hydration of the aldehyde.

Acetaldehyde↗
PubMed1973

A family of three related satellite DNAs in Drosophila virilis.

Isolated single DNA strands of satellites II or III of Drosophila virilis form hybrid duplexes with the complementary single strands of satellite I. The hybrids denature at a higher temperature than controls, renature rapidly, and form bands of hybrid density in neutral CsCl. Isolated single strands of satellite II do not form clear-cut duplexes with the complementary strands of satellite III. Mixtures of satellites II and III denature at the same temperature as controls, and do not form bands in neutral CsCl. Therefore, satellite I-II and I-III complexes are extensively base paired, while satellite II-III complexes are minimally base paired. These experiments demonstrate partial homology among the three satellites, and suggest an evolutionary relationship among them. They also suggest that satellites and other repeated sequences from related species, which do not form hybrids in vitro, could have a common evolutionary origin, but have accumulated enough base substitutions to lose interspecific homology demonstrable by hybrid duplex formation.

Animals↗
PubMed1973

Terminal synthesis of xanthommatin in Drosophila melanogaster. 3. Mutational pleiotropy and pigment granule association of phenoxazinone synthetase.

Phenoxazinone synthetase, which catalyzes the condensation of 3-hydroxykynurenine to xanthommatin, the brown eye pigment of Drosophila, is shown to exist in association with a particle which resembles the cytologically defined Type I pigment granule. Several classical eye color mutants (v, cn, st, ltd, cd, w), including two which effect other enzymes in the xanthommatin pathway (v, cn), have low levels of phenoxazinone synthetase activity and disrupt the normal association of the enzyme with the pigment granule. A model is proposed depicting several structural and enzymatic interrelationships involved in the developmental control of xanthommatin synthesis in Drosophila.

Amino Acids↗