RESUMO
The bacterial D-alanine carboxypeptidases (CPases) remove C-terminal D-alanyl residues from sugar-peptide cell wall precursors. The CPases have many characteristics in common with the high-M(r) penicillin-binding proteins (PBPs) whose inhibition by beta-lactam antibiotics is lethal. The CPases are attractive as model PBPs, because of their relatively lower M(r) and higher activity in vitro. We have cloned and sequenced the Bacillus stearothermophilus gene (dacA) coding for a membrane-bound CPase. The nucleotide (nt) sequence of the gene is homologous to that of the Escherichia coli and Bacillus subtilis dacA loci, which also code for membrane-bound CPases. E. coli host cells lysed when expression of B. stearothermophilus dacA was induced. The same coding sequence was expressed in the methylotrophic yeast, Pichia pastoris, using the alcohol oxidase-1 (AOX1) promoter. Over 100 micrograms/ml of CPase was efficiently secreted into the medium after induction by methanol, without adversely affecting this host. The yeast product is indistinguishable from the native enzyme in structure and activity. The ability to secrete large amounts of heterologous protein and the lack of endogenous peptidoglycan metabolism makes P. pastoris an attractive candidate for the production of PBPs.
Assuntos
Proteínas de Bactérias/química , Proteínas de Transporte/química , Genes Bacterianos , Geobacillus stearothermophilus/enzimologia , Geobacillus stearothermophilus/genética , Muramilpentapeptídeo Carboxipeptidase/química , Muramilpentapeptídeo Carboxipeptidase/genética , Pichia/enzimologia , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sequência de Bases , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Parede Celular/química , Clonagem Molecular , Escherichia coli , Proteínas Fúngicas/biossíntese , Proteínas Fúngicas/química , Modelos Estruturais , Dados de Sequência Molecular , Muramilpentapeptídeo Carboxipeptidase/metabolismo , Resistência às Penicilinas , Penicilinas/metabolismo , Pichia/genética , Proteínas Recombinantes de Fusão , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Especificidade da Espécie , Relação Estrutura-AtividadeRESUMO
An analytic study of electroretinogramms (ERG) from 280 patients under antimalarial therapy has been made. The pratician has stopped treatment in 4.8% of the ERG. Among the investigated parameters, the only statistic difference is the cumulative doses.
Assuntos
Antimaláricos/intoxicação , Doenças Retinianas/induzido quimicamente , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Eletrorretinografia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Doenças Retinianas/prevenção & controleRESUMO
Surgery can help patients affected with Graves' myositis. This surgery is very delicate because it is performed on muscles modified with retractile sclerosis transforming muscular fibers into fibrous and rigid strings. The surgical treatment must be decided with endocrinologists. Many surgical stages are usually necessary. Reunion procedures must be chosen, while unpredictable muscular resections must be banished.
Assuntos
Doença de Graves/complicações , Miosite/cirurgia , Doenças do Nervo Oculomotor/cirurgia , Humanos , Miosite/etiologia , Miosite/patologia , Doenças do Nervo Oculomotor/etiologia , Doenças do Nervo Oculomotor/patologiaRESUMO
The transformation of 22-hydroxy-23,24-bisnorchol-4-en-3-one to 7alpha-22-dihydroxy-23,24-bisnorchol-4-en-3-one by Botryodiploida theobromae, Lasiodiplodia theobromae, and various Botryosphaeria strains is described. Factors affecting the reaction were incubation temperature, sonication of the substrate, and addition of 2,2'-dipyridyl, extra carbohydrate, and Amberlite XAD-7. The enzyme responsible for the reaction appeared to be very specific and was not characteristic of all members of the genera listed above.
RESUMO
A new antibiotic, 3-O-oleandrosyl-5-O-desosaminylerythronolide A oxime (3) was produced from erythronolide A oxime (1) by the oleandomycin-producing culture, Streptomyces antibioticus ATCC 11891. The structure of 3 was determined by degradative studies and confirmed by X-ray analysis. Compound 3 was found to be less active, but more stable to acid, then erythromycin A oxime.