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1.
Nucleosides Nucleotides Nucleic Acids ; 36(10): 652-665, 2017 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-29185863

RESUMO

The separation of the diastereoisomers of the nucleoside derivatives of uridine, inosine and adenosine was performed by HPLC using chiral and no chiral columns, it was observed with the no chiral columns the resolution was good enough to determine diastereoisomeric excess. These methods were compared with 1H NMR, and no significant differences were observed between the three techniques. Diastereoisomeric uridine (3a), inosine (3b) and adenosine (4c) cyanohydrins were resolved by 1H nuclear magnetic resonance (1H NMR), chiral normal phase-high-performance liquid chromatography-diode array detector (NP-HPLC-DAD) and reversed phase (RP-HPLC-DAD); these methods allowed the assesment of the percent diastereoisomeric excess (% de) of the nucleosidic cyanohydrins of 3a (4, 6 and 4), 3b (10, 8 and 6) and 4c (4, 4 and 4). To the best of our knowledge, there are no reports using analytical techniques for the separation of the epimers of 3a, 3b and 4c.


Assuntos
Adenosina/química , Inosina/química , Nitrilas/química , Uridina/química , Cromatografia Líquida de Alta Pressão , Cromatografia de Fase Reversa , Espectroscopia de Ressonância Magnética , Estereoisomerismo
2.
Bioresour Technol ; 146: 794-798, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23993287

RESUMO

In this study, chitin oligosaccharides have been successfully produced using chitinases from submerged fermentation of Lecanicillium lecanii. The highest Hex, Chit and Prot production was 0.14, 0.26 and 2.05 U/mg of protein, respectively, which were attained varying pH from 5 to 8 after 96 h. Culture conditions conducted at constant pH of 6 resulted in significantly lower enzyme production. The crude enzyme was partially purified by salting out with (NH4)2SO4 followed by size exclusion chromatography to isolate the chitinase mixture for further chitin hydrolysis assays. In this regard, chitin substrates were pretreated with sonication and steam explosion prior to enzymatic reaction. Structural changes were observed with steam explosion with 11.28% reduction of the crystallinity index attained with the lowest chitin/water ratio (0.1g/mL). Pretreated chitins reached the highest production of reducing sugars (0.37 mg/mL) and GlcNAc (0.59 mg/mL) in 23.6% yield.


Assuntos
Quitina/biossíntese , Quitinases/química , Quitosana/química , Hypocreales/enzimologia , Oligossacarídeos/biossíntese , Carboidratos/química , Cristalização , Enzimas/química , Fermentação , Concentração de Íons de Hidrogênio , Hidrólise , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Vapor , Temperatura , Fatores de Tempo , Ultrassom
3.
Bioprocess Biosyst Eng ; 36(3): 383-7, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22869004

RESUMO

Hyperbranched poly-L-lactides have been synthesized by eROP in [C4MIM][PF6] media. The bis(hydroxymethyl)butyric acid molecule was used as the AB2 core co-monomer and immobilized lipase B from Candida antarctica as biocatalyst. The degree of branching could be controlled by the reaction conditions, with the maximum achieved being 0.21. The successful achievement of the hyperbranched structure is attributed to the high solvent power of substrates and products in the ionic liquid besides sustained lipase activity.


Assuntos
Candida/enzimologia , Líquidos Iônicos/química , Lipase/química , Poliésteres/química , Catálise , Enzimas Imobilizadas/química , Proteínas Fúngicas/química , Íons/química , Espectroscopia de Ressonância Magnética , Polímeros/química , Solventes/química , Temperatura
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