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The extraction and hydrolysis of steroid monoglucuronides.

ABSTRACT: 1. A method in use for the extraction of urinary steroid conjugates has been applied to study the recovery of synthetic steroid monoglucuronides from aqueous solution. 2. In the presence of dissolved ammonium sulphate (50g./100ml.), ether-ethanol (3:1, v/v, 3x0.5vol.) extracted the monoglucuronides of steroids of the C(18), C(19) and C(21) series, quantitatively at values pH2-9. 3. The hydrolysis of the synthetic steroid monoglucuronides by beta-glucuronidase (Patella vulgata) has been examined with reference to the pH value of the medium, enzyme concentration and substrate concentration. 4. The rate of hydrolysis of steroid monoglucuronides was dependent upon steroid structure and upon site of conjugation. 5. The rate of hydrolysis of the monoglucuronides decreased in the order C-3 (phenolic) >C-3beta>C-17beta>C-3alpha.

SUBMITTER: Kellie AE

PROVIDER: S-EPMC1265194 | biostudies-other | 1966 Sep

REPOSITORIES: biostudies-other

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Project description:BACKGROUND:A two-stage chemical pretreatment of corn stover is investigated comprising an NaOH pre-extraction followed by an alkaline hydrogen peroxide (AHP) post-treatment. We propose that conventional one-stage AHP pretreatment can be improved using alkaline pre-extraction, which requires significantly less H2O2 and NaOH. To better understand the potential of this approach, this study investigates several components of this process including alkaline pre-extraction, alkaline and alkaline-oxidative post-treatment, fermentation, and the composition of alkali extracts. RESULTS:Mild NaOH pre-extraction of corn stover uses less than 0.1 g NaOH per g corn stover at 80°C. The resulting substrates were highly digestible by cellulolytic enzymes at relatively low enzyme loadings and had a strong susceptibility to drying-induced hydrolysis yield losses. Alkaline pre-extraction was highly selective for lignin removal over xylan removal; xylan removal was relatively minimal (~20%). During alkaline pre-extraction, up to 0.10 g of alkali was consumed per g of corn stover. AHP post-treatment at low oxidant loading (25 mg H2O2 per g pre-extracted biomass) increased glucose hydrolysis yields by 5%, which approached near-theoretical yields. ELISA screening of alkali pre-extraction liquors and the AHP post-treatment liquors demonstrated that xyloglucan and ?-glucans likely remained tightly bound in the biomass whereas the majority of the soluble polymeric xylans were glucurono (arabino) xylans and potentially homoxylans. Pectic polysaccharides were depleted in the AHP post-treatment liquor relative to the alkaline pre-extraction liquor. Because the already-low inhibitor content was further decreased in the alkaline pre-extraction, the hydrolysates generated by this two-stage pretreatment were highly fermentable by Saccharomyces cerevisiae strains that were metabolically engineered and evolved for xylose fermentation. CONCLUSIONS:This work demonstrates that this two-stage pretreatment process is well suited for converting lignocellulose to fermentable sugars and biofuels, such as ethanol. This approach achieved high enzymatic sugars yields from pretreated corn stover using substantially lower oxidant loadings than have been reported previously in the literature. This pretreatment approach allows for many possible process configurations involving novel alkali recovery approaches and novel uses of alkaline pre-extraction liquors. Further work is required to identify the most economical configuration, including process designs using techno-economic analysis and investigating processing strategies that economize water use.

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The extraction and hydrolysis of steroid monoglucuronides.

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