ONE-POT ENZIMATIC DEPOLYMERIZATION OF CELLULOSE IN IONIC LIQUIDS

Green alternatives to fossil-based fuels are very attractive and can be produced from cellulosic materials. Cellulose is the primary product of photosynthesis in plants and has immense importance as a renewable raw material. The production of biofuels starting from cellulose is gaining increasing attention and obviously implies the partial or total hydrolysis of cellulose: enzymatic processes are considered the most promising technology [1]. Cellulases (EC 3.2.1.4) are the enzymes most commonly employed to selectively depolymerize cellulose in buffered aqueous solvents. Because of the very low solubility of cellulose due to its highly organized structure, enzymatic conversions proceed at very slow reaction rates and require the dissolution in a solvent to facilitate the access of cellulases to cellulosic substrates. To improve the yield of fermentable monosaccharides, pretreatments of cellulose, such as thermal, chemical or physical treatment, have been applied to afford a better enzymatic conversion [2]. Ionic liquids (ILs) have been increasingly recognized as excellent solvents for dissolution and pretreatment of cellulose but it was previously reported that ILs induce usually fast enzyme deactivation by protein unfolding [3]. In the present work we present a study on a single-batch, homogeneous phase enzymatic hydrolysis of cellulose using three commercial ILs. We have tested two native proteins from Trichoderma reesei and Humicola insolens and two engineered proteins from T. reesei and Streptomyces sp.. In some cases ILs don’t denature the cellulases used but increase their operational stability as compared to standard buffer solutions and facilitate the dissolution of cellulose. Interestingly, the stability of the four cellulases in the presence of the ILs allows to set-up a procedure lacking of the cellulose pretreatment step. We believe that this strategy could be amenable of scale-up and innovative industrial applications for the efficient one-batch conversion of inexpensive cellulosic materials into derivatives (biofuels, derivatized cellulose, monosaccharides for fine chemicals, etc.) with high potential commercial interest and in the framework of environmentally friendly chemistry. References [1] A.P. dadi, S. Varanasi, C.A. Schall. Biotechnol Bioeng, 95(5), 904-910, (2006). [2] M.B. Turner, S.K. Spear, J.G. Huddleston, J.D. Holbrey, R.D. Rogers. Green Chem, 5(4), 443-447, (2003). [3] S.D. Zhu, Y.X. Wu, Q.M. Chen, C. Wang, S. Jin, Y. Ding, G. Wu, Green Chem, 8, 325-327, (2006)

2,5-Diisopropenylthiophene by Suzuki\u2013Miyaura cross-coupling reaction and its exploitation in inverse vulcanization: a case study

A novel thiophene derivative, namely 2,5-diisopropenylthiophene (DIT) was synthetized by Suzuki\u2013Miyaura cross-coupling reaction (SMCCR). The influence of reaction parameters, such as temperature, solvent, stoichiometry of reagents, role of the base and reaction medium were thoroughly discussed in view of yield optimization and environmental impact minimization. Basic design of experiment (DoE) and multiple linear regression (MLR) modeling methods were used to interpret the obtained results. DIT was then employed as a comonomer in the copolymerization with waste elemental sulfur through a green process, inverse vulcanization (IV), to obtain sulfur-rich polymers named inverse vulcanized polymers (IVPs) possessing high refractive index (n z 1.8). The DIT comonomer was purposely designed to (i) favor the IV process owing to the high reactivity of the isopropenyl functionalities and (ii) enhance the refractive index of the ensuing IVPs owing to the presence of the sulfur atom itself and to the high electronic polarizability of the p-conjugated thiophene ring. A series of random sulfur-rdiisopropenylthiophene (S-r-DIT) copolymers with sulfur content from 50 up to 90 wt% were synthesized by varying the S/DIT feed ratio. Spectroscopic, thermal and optical characterizations of the new IVPs were carried out to assess their main chemical\u2013physical feature

A METABOLIC-LIKE CYCLE FOR SYNTHETIC APPLICATIONS

Systems Biocatalysis is a new approach consisting of organizing enzymes in vitro to generate an artificial metabolism for synthetic purposes. The interconversion of functional groups is the main objective of biocatalysis, and systems organizing a series of enzymes to achieve a multi-step reaction have been reported. The assembly of essentially the same enzymes utilized in Nature to drive the transformation of carbohydrates towards useful synthetic intermediates [1] has been referred to as an artificial metabolism. SysBiocat aims at a similar goal addressing the generalization and organization of group of enzymes (a tool-box) able to perform a series of reactions of general synthetic utility where the feasibility is connected with the obtainment of enzymes of wide substrate specificity or in a rich array of variable common catalytic functions. [2] As a demonstration of this concept, we have recently assembled a biochemical like cycle (Asp-cycle) connecting among them an unsaturated carboxylate (fumaric acid), an alpha-amino acid (L-aspartic acid), a keto acid (oxalacetic acid) and the corresponding alpha-hydroxyacid (D- or L-malic acid). [3] In this view, the obtained cycle may be exploited by coupling it with synthetically relevant reactions which are driven to completion thanks to one or more irreversible steps in the reaction sequence. ____ [1] W.D. Fessner, C. Walter, “Artificial metabolism”, Angew Chem Int Ed, 1992, 31, p. 614 [2] U. T. Bornscheuer, G. W. Huisman, R. J. Kazlauskas, S. Lutz, J. C. Moore, K. Robins, “Engineering The Third Wave Of Biocatalysis”, Nature, 2012, 485, p. 185 [3] D. Tessaro, L. Pollegioni, L. Piubelli, P. D’Arrigo, S. Servi, “Systems Biocatalysis: An Artificial Metabolism for Interconversion of Functional Groups”, ACS Catalysis, 2015, 5, p. 160

Physical performance and clinical outcomes in dialysis patients: a secondary analysis of the EXCITE trial.

Background/Aims: Scarce physical activity predicts shorter survival in dialysis patients. However, the relationship between physical (motor) fitness and clinical outcomes has never been tested in these patients. Methods: We tested the predictive power of an established metric of motor fitness, the Six-Minute Walking Test (6MWT), for death, cardiovascular events and hospitalization in 296 dialysis patients who took part in the trial EXCITE (ClinicalTrials.gov Identifier: NCT01255969). Results: During follow up 69 patients died, 90 had fatal and non-fatal cardiovascular events, 159 were hospitalized and 182 patients had the composite outcome. In multivariate Cox models - including the study allocation arm and classical and non-classical risk factors - an increase of 20 walked metres during the 6MWT was associated to a 6% reduction of the risk for the composite end-point (P=0.001) and a similar relationship existed between the 6MWT, mortality (P<0.001) and hospitalizations (P=0.03). A similar trend was observed for cardiovascular events but this relationship did not reach statistical significance (P=0.09). Conclusions: Poor physical performance predicts a high risk of mortality, cardiovascular events and hospitalizations in dialysis patients. Future studies, including phase-2 EXCITE, will assess whether improving motor fitness may translate into better clinical outcomes in this high risk populatio

Characterization of the patterns of drug-resistance mutations in newly diagnosed HIV-1 infected patients naïve to the antiretroviral drugs

<p>Abstract</p> <p>Background</p> <p>The transmission of HIV-1 drug-resistant strains in drug naive patients may seriously compromise the efficacy of a first-line antiretroviral treatment. To better define this problem, a study in a cohort of newly diagnosed HIV-1 infected individuals has been conducted. This study is aimed to assess the prevalence and the patterns of the mutations recently associated with transmitted drug resistance in the reverse transcriptase (RT) and in protease (PR) of HIV-1.</p> <p>Methods</p> <p>Prevalence of transmitted drug resistant strains is determined in 255 newly diagnosed HIV-1 infected patients enrolled in different counselling and testing (CT) centres in Central Italy; the Avidity Index (AI) on the first available serum sample is also used to estimate time since infection. Logistic regression models are used to determine factors associated with infection by drug resistant HIV-1 strains.</p> <p>Results</p> <p>The prevalence of HIV-1 strains with at least one major drug resistance mutation is 5.9% (15/255); moreover, 3.9% (10/255) of patients is infected with HIV nucleoside reverse transcriptase inhibitor (NRTI)-resistant viruses, 3.5% (9/255) with HIV non-NRTI-resistant viruses and 0.4% (1/255) with HIV protease inhibitor (PI)-resistant viruses. Most importantly, almost half (60.0%) of patients carries HIV-1 resistant strains with more than one major drug resistance mutation. In addition, patients who had acquired HIV through homosexual intercourses are more likely to harbour a virus with at least one primary resistance mutation (OR 7.7; 95% CI: 1.7–35.0, P = 0.008).</p> <p>Conclusion</p> <p>The prevalence of drug resistant HIV-1 strains among newly diagnosed individuals in Central Italy is consistent with the data from other European countries. Nevertheless, the presence of drug-resistance HIV-1 mutations in complex patterns highlights an additional potential risk for public health and strongly supports the extension of wide genotyping to newly diagnosed HIV-1 infected patients.</p