The employment of 2-deoxyribose-5-phosphate aldolase (DERA) stands as a prevalent biocatalytic route for synthesizing statin side chains. The main problem with this pathway is the low stability of ...the enzyme. In this study, mesocellular silica foam (MCF) with different pore sizes was used as a carrier for the covalent immobilization of DERA. Different functionalizing and activating agents were tested and kinetic modeling was subsequently performed. The use of succinic anhydride as an activating agent resulted in an enzyme hyperactivation of approx. 140%, and the stability almost doubled compared to that of the free enzyme. It was also shown that the pore size of MCF has a decisive influence on the stability of the DERA enzyme.
To assess the prognostic role of admission C-reactive protein (CRP) in patients with acute aortic dissection (AAD).
We searched Medline and Scopus for studies published before January 2019 that ...evaluated the prognostic impact of CRP on all-cause mortality during short- and mid-term follow-up period in patients with AAD. Additional studies were identified by manual search of the references from the original studies. Receiver-operating characteristic curves were used to determine the optimal cut-off values of admission CRP for the prediction of mortality, and patients were categorized into two groups based on the CRP cut-off levels.
Medline, Scopus, and manual literature search yielded 138 citations. Based on the title and abstract analysis and review of potentially relevant studies, five studies, involving 711 patients, were included in the final analysis. Multivariate statistical analysis was performed in all the studies. The median admission CRP value across the studies was 13 mg/L (range 4-21 mg/L). Two out of three studies that evaluated in-hospital outcome and all of the studies that evaluated medium-term outcome reported a significant association between elevated CRP values and mortality. The studies that included treatment strategy (surgery vs conservative treatment) as a confounding variable confirmed a significant effect of elevated CRP values on both in-hospital and mid-term unfavorable outcomes.
This systematic review demonstrated a clear association between elevated admission serum CRP levels and increased in-hospital and mid-term mortality risk in AAD.
Acute aortic dissection (AAD) is a serious medical emergency that requires early diagnosis and rapid treatment. Whether cardiac troponin could be an independent prognostic marker in patients with ...type A AAD is still unknown. We systematically searched Medline and Scopus to identify all observational cohort studies published before January 2020 that compared outcome (inhospital mortality) in patients with type A AAD with and without troponin elevation on admission. Four studies with 412 patients were included in final analysis (median age 59 years, 65% of males). A total of 124 (30%) patients died during in-hospital stay, and 73% underwent surgery. Elevated troponins (39.6% of patients) were associated with an increased risk of short-term mortality (adjusted odds ratio 1.26; 95% confidence interval 1.08-1.47), with low heterogeneity among studies (I.sup.2=29.81%). Elevated troponins on admission are independently associated with increased in-hospital mortality in type A AAD. Key words: Troponin; Aortic dissection; Mortality; Meta-analysis
Background
Atrial fibrillation (AF) is associated with adverse outcomes in terms of survival and morbidity. Peripheral artery disease (PAD) and AF share several common risk factors and often coexist. ...Whether AF has a prognostic role in patients with PAD has not been extensively studied.
Hypothesis
AF is associated with major adverse cardiac events (MACE) and mortality in symptomatic PAD patients.
Methods
Using MEDLINE and Scopus, we searched for studies published before December 2016 that evaluated cardiovascular outcomes based on the presence/absence of AF in a prospective manner with a follow‐up period of ≥12 months. The outcomes were reported using a random‐effects model, and heterogeneity was assessed using the I2 statistic. Sensitivity analyses were performed to test the contribution of each study to the overall results.
Results
Six prospective studies (Newcastle‐Ottawa score range, 7–9) with 14 656 patients were included in the final analysis (age range, 66–70 years; median follow‐up, 1.4 years). Our pooled analysis found a significant association between AF and mortality (odds ratio: 2.52, 95% confidence interval: 1.91‐3.34, I2 = 32.6%), without evidence of publication bias (P = 0.63). Meta‐analysis showed a significant impact of AF on MACE (odds ratio: 2.54, 95% confidence interval: 1.78‐3.63, I2 = 74.3%), without detected publication bias (P = 0.08).
Conclusions
AF is associated with increased risk of mortality and MACE in symptomatic PAD.
In this work the green synthesis of gold nanoparticles (Au-NPs) using the oxidoreductive enzymes
Myriococcum thermophilum
cellobiose dehydrogenase (
Mt
CDH),
Glomerella cingulata
glucose ...dehydrogenase (
Gc
GDH), and
Aspergillus niger
glucose oxidase (
An
GOX)) as bioreductants was investigated. The influence of reaction conditions on the synthesis of Au-NPs was examined and optimised. The reaction kinetics and the influence of Au ions on the reaction rate were determined. Based on the kinetic study, the mechanism of Au-NP synthesis was proposed. The Au-NPs were characterized by UV–Vis spectroscopy and transmission electron microscopy (TEM). The surface plasmon resonance (SPR) absorption peaks of the Au-NPs synthesised with
Mt
CDH and
Gc
GDH were observed at 535 nm, indicating an average size of around 50 nm. According to the image analysis performed on a TEM micrograph, the Au-NPs synthesized with
Gc
GDH have a spherical shape with an average size of 2.83 and 6.63 nm after 24 and 48 h of the reaction, respectively.
Key points
• The Au NPs were synthesised by the action of enzymes CDH and GDH.
• The synthesis of Au-NPs by CDH is related to the oxidation of cellobiose.
• The synthesis of Au-NPs by GDH was not driven by the reaction kinetic.
Graphical Abstract
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•First time SCM model is used for the evaluation of inhibitors impact on LPMO activity.•Causalities of the molecular descriptors and LPMO activity is based on DAG.•The maximal ...causality for LPMO is effected by BIC3 and GATS4c descriptor.•SCM is powerful tool for the prediction of enzyme and inhibitors interaction.
Lytic-polysaccharide monooxygenase (LPMO) is one of the most important enzyme involved in biocatalytic lignocellulose degradation, and therefore inhibition of LPMO has significant effects on all related processes. Structural causality model (SCM) were established to evaluate impact of phenolic by-products in lignocellulose hydrolysates on LPMO activity. The molecular descriptors GATS4c, ATS2m, BIC3 and VR2_Dzs were found to be significant in describing inhibition. The causalities of the molecular descriptors and LPMO activity are determined by evaluating the directed acyclic graph (DAG) and the d-separation algorithm. The maximum causality for LPMO activation is β = 0.79 by BIC3 and the maximum causality of inhibition is β = -0.56 for the GATS4c descriptor. The model has the potential to predict the inhibition of LPMO and its application could be useful in selecting an appropriate lignocellulose pretreatment method to minimise the production of a potent inhibitor. This will subsequently lead to more efficient lignocellulose degradation process.
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•Statin chain precursor was successfully synthesized by DERA/AlDH/NOX system•Enzymes kinetic and stability studies in reactions involved in the process are given•Sequential one-pot is ...preferable strategy to avoid side reaction of DERA substrates•A one-pot system contributed to enzyme stability
Statins are a group of drugs used for lowering cholesterol levels in the human bloodstream to prevent cardiovascular diseases and its synthesis is a challenge because of chemical and stereochemical requirements. In this work, a multi-enzyme one-pot sequential strategy was employed to obtain lactonized statin side-chain precursor and was compared to the two-pot process. The enzymatic production of this valuable product is rarely examined comparing to the traditional chemical methods. The examined cascade consisted of two consecutive reactions: lactol production by the 2-deoxyribose-5-phosphate aldolase (DERA)-catalysed double aldol addition of acetaldehyde and chloroacetaldehyde and its oxidation by the NAD-dependent aldehyde dehydrogenase (AlDH). NADH oxidase (NOX) was employed for the coenzyme regeneration. The insight in all reactions of the system was performed by enzyme kinetic and stability studies. Based on these data the mathematical models were developed and validated in a batch reactor. The oxidation was carried out using both purified (two-pot) and crude lactol (one-pot) obtained in the DERA-catalysed reaction. Better process metrics and greater stability of the AlDH was observed in one-pot system, thus demonstrating an additional benefit in favor of running multi-enzymatic (cascade) processes.
Lignocelulozna biomasa je važan obnovljivi izvor energije i koristi se kao sirovina u proizvodnji biogoriva druge generacije. Zbog vrlo složene strukture, učinkovita enzimska hidroliza ...lignoceluloznebiomase je ključni izazov današnjice. Litička polisaharidna monooksigenaza (LPMO) je nedavno otkrivena vrsta enzima koji sadrže bakar, a imaju značajnu ulogu u oksidativnoj razgradnji netopivih biljnih polisaharida i topivih oligosaharida. Stoga je prepoznat kao jedan od bitnih enzima u održivoj pretvorbi lignocelulozne biomase, a važnost ovog enzima potvrđena je brojnim istraživanjima. Nakon reduktivne aktivacije, LPMO cijepa supstrat i potiče razgradnju biomase hidrolitičkim enzimima. U ovom preglednom radu, opisana je uloga LPMO u razgradnji lignocelulozne biomase s naglaskom na strukturu LPMO i mehanizma djelovanja LPMO na celuloznim supstratima.
Lignocellulosic biomass is an important renewable energy source and is used as a feedstock for the production of second generation biofuels. Due to its very complex structure, efficient enzymatic hydrolysis of lignocellulosic biomass is a major challenge today. Lytic polysaccharide monooxygenase (LPMO) is a recently discovered type of copper-containing enzyme that plays a significant role in the oxidative degradation of insoluble plant polysaccharides and soluble oligosaccharides. Therefore, it is considered one of the essential enzymes for the sustainable conversion of lignocellulosic biomass, and its importance has been confirmed by numerous studies. After reductive activation, LPMO cleaves the substrate and promotes biomass degradation by hydrolytic enzymes. In this review, the role of LPMO in the degradation of lignocellulosic biomass is described, focusing on the structure of LPMO and the mechanism of action of LPMO on cellulosic substrates.
Kemijske modifikacije nanoceluloze Rezić, Tonči; Perković, Ivan; Andlar, Martina ...
Hrvatski časopis za prehrambenu tehnologiju, biotehnologiju i nutricionizam,
12/2022, Letnik:
17, Številka:
1-2
Journal Article, Paper
Odprti dostop
Izuzetna fizikalno-kemijska svojstva nanoceluloze omogućavaju njezinu primjenu u biomedicini, farmaceutskoj industriji, proizvodnji papira i konstrukcijskih materijala te u proizvodnji materijala ...posebnih svojstava. Danas se istražuju novi postupci proizvodnje nanoceluloze korištenjem novih tehnologija, a s ciljem smanjenja utroška energije i proizvodnje nanoceluloze naprednih svojstava. Vrsta i zastupljenost funkcionalnih grupa na površini nanoceluloze određuju njezina svojstva i potencijalnu primjenu. U ovome radu biti će opisane kemijske metode modifikacije nanoceluloze kao i utjecaj pojedine metode na fizikalno-kemijska svojstva nanoceluloze.
The exceptional physical and chemical properties of nanocellulose enable the production of specific materials and applications in the fields of medicine, pharmaceuticals, paper and construction materials. New methods of producing nanocellulose are being explored today with new technologies to reduce energy consumption and obtain advanced properties of nanocellulose. The nature and presence of functional groups on the surface of nanocellulose determine its properties and potential applications. This article describes the chemical methods used to modify nanocellulose and their influence on the physicochemical properties of nanocellulose.
Proizvodnja nanoceluloze iz lignoceluloznih sirovina Rezić, Tonči; Drdić, Maria; Radić, Ines ...
Hrvatski časopis za prehrambenu tehnologiju, biotehnologiju i nutricionizam,
12/2022, Letnik:
17, Številka:
1-2
Journal Article, Paper
Odprti dostop
Nanoceluloza je prirodan i biorazgradiv materijal koji se dobiva iz obnovljivih lignoceluloznih sirovina kao sto su drvna biomasa, poljoprivredni ostaci i ostaci iz proizvodnje celuloze i papira. U ...posljednje vrijeme nanoceluloza kao zeleni materijal modernog doba zadobiva sve veći interes zbog svojih atraktivnih karakteristika kao što su izvrsna mehanička svojstva, velika površina te veliki broj hidroksilnih skupina koji omogućava veliki raspon modifikacija materijala. U ovome radu biti će opisani načini proizvodnje nanoceluloze iz lignoceluloznih sirovina korištenjem mehaničkih i fizikalno-kemijskih metoda, a poseban naglasak će bit dan na metode predobrade korištenjem enzima.
Nanocellulose is a natural and biodegradable material derived from renewable lignocellulosic raw materials such as wood biomass, agricultural residues, and residues from cellulose and paper manufacturing. Recently, nanocellulose has attracted increasing interest as a green material of the modern era due to its attractive characteristics such as excellent mechanical properties, large surface area, and large number of hydroxyl groups, which allow a wide range of material modifications. In this paper, the methods of producing nanocellulose from lignocellulosic raw materials using mechanical and physicochemical processes are described, with particular attention paid to pretreatment methods using enzymes
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