Konvektivno sušenje parčića ploda batata (Ipomoea batatas (L.) Lam), zavisnost od predtretmana

The dried of pieces of sweet potatoes (Ipomoea batatas (L.) Lam) was carried in experimental convective cabinet drier with loess. This vegetable was rich in beta carotene and was not sufficiently in our countries. The dried process was carried at 55oC, and weight changes were measured every 15 minutes. Were performed three pretreatments: dried with pretreatment, blanched with the 1% vitamin C and 5% NaCl and without pretreatment. Blanched was carried in water at 60oC, for 3 minutes. The moisture content of raw sweet potato was 76.40%, but in dried material value from 16.90 to 19.59%, respectively. Rehydration values were measure of the quality of the dried process. The best results were obtained to dried small pieces of sweet potato without pretreatment, than rehydration was 83.37%.Sušenje parčića ploda batata (Ipomoea batatas (L.) Lam) ili slatkog krompira vršeno je u eksperimentalnoj konvektivnoj sušari sa lesama. Ova povrtarska biljka bogata je beta karotenom, a nedovoljno se koristi u našoj zemlji. Proces sušenja odvijao se na 55oC, a merena je promena mase na svakih 15 minuta. Rađena su tri predtretmana blanširanjem: bez dodataka (predtretman I), sa dodatkom 1% vitamina C (predtretman II), sa dodatkom 5% NaCl (predtretman III) i sušenje bez predtretmana (kontrola). Blanširanje je vršeno u destilovanoj vodi temperature 60oC za 3 minuta, sa i bez dodataka. Sadržaj vlage u sirovom plodu batatu bio je 76,40%, a u osušenom materijalu kretao se od 16,90 do 19,59 %. Stepen rehidratacije korišćen je kao mera kvaliteta procesa sušenja. Najbolji rezultati dobijeni su kod sušenja parčića ploda batata bez predtretmana, čiji je stepen rehidratacije bio 83,37%

Immunomodulatory components of Trichinella spiralis excretory-secretory products with lactose-binding specificity.

The immunomodulatory potential of Trichinella spiralis muscle larvae excretory-secretory products (ES L1) has been well documented in vitro on dendritic cells (DCs) and in animal models of autoimmune diseases. ES L1 products possess the potential to induce tolerogenic DCs and consequently trigger regulatory mechanisms that maintain immune homeostasis. The use of ES L1 as a potential treatment for various inflammatory disorders proved to be beneficial in animal models, although the precise immunomodulatory factors have not yet been identified. This study aimed at the isolation and characterization of ES L1 components that possess galectin family member properties. Galectin-1-like proteins (TsGal-1-like) were isolated from ES L1 based on the assumption of the existence of a lactose-specific carbohydrate-recognition domain and were recognized by anti-galectin-1 antibodies in Western blot. This TsGal-1-like isolate, similar to galectin-1, induced DCs with tolerogenic properties and hence, the capacity to polarize T cell response towards a regulatory type. This was reflected by a significantly increased percentage of CD4+CD25+Foxp3+ regulatory T cells and significantly increased expression of IL-10 and TGF-β within this cell population. Proteomic analysis of TsGal-1-like isolate by mass spectrometry identified nineteen proteins, seven with annotated function after blast analysis against a database for T. spiralis and the UniProt database. To our surprise, none of the identified proteins possesses homology with known galectin family members. Nevertheless, the isolated components of ES L1 possess certain galectin-1 properties, such as specific lactose binding and the potential to elicit a regulatory immune response, so it would be worth further investigating the structure of sugar binding within isolated proteins and its biological significance

High frequency of the R75Q CFTR variation in patients with chronic obstructive pulmonary disease

AbstractWe performed the complete screening of the CFTR gene in a group of 31 patients with COPD in order to investigate the impact of mutations and polymorphisms in the CFTR gene. The cumulative frequency of CFTR mutations (17.74%) was significantly higher than in our general population (P<0.0001). The R75Q was significantly overrepresented in COPD patients (8.06%; P=0.002). In all patients carrying the R75Q chronic bronchitis was a dominant symptom of COPD, and all were homozygous for the V470 allele. These findings suggest that R75Q mutation could be characteristic CFTR variant for COPD patients

Anomalous scattering analysis of Agrobacterium radiobacter phosphotriesterase: the prominent role of iron in the heterobinuclear active site

Bacterial phosphotriesterases are binuclear metalloproteins from which the catalytic mechanism has been studied with a variety of techniques, principally using active sites reconstituted in vitro from apo-enzymes. Here, atomic absorption spectroscopy and anomalous X-ray scattering and have been used to determine the identity of the metals incorporated into the active site in vivo. We have recombinantly expressed the phosphotriesterase from Agrobacterium radiobacter (OpdA) in Escherichia coli grown in medium supplemented with 1 mM CoCl2, and in unsupplemented medium. Anomalous scattering data, collected from a single crystal at the Fe-K, Co-K and Zn-K edges, indicate that iron and cobalt are the primary constituents of the two metal binding sites in the catalytic centre ( and ), in protein expressed in E. coli grown in supplemented medium. Comparison to OpdA expressed in unsupplemented medium demonstrates that the cobalt present in the supplemented medium replaced zinc at the -position of the active site, which results in an increase in the catalytic efficiency of the enzyme. These results suggest an essential role for iron in the catalytic mechanism of bacterial phosphotriesterases, and that they are natively heterobinuclear iron-zinc enzymes

Promiscuous metallo-β-lactamases: MIM-1 and MIM-2 may play an essential role in quorum sensing networks

MIM-1 and MIM-2 are two recently identified metallo-β-lactamases (MBLs) from Novosphingobium pentaromativorans and Simiduia agarivorans, respectively. Since these organisms are non-pathogenic we speculated that the biological role(s) of MIM-1 and MIM-2 may not be related to their MBL activity. Although both sequence comparison and homology modeling indicate that these proteins are homologous to well-known MBLs such as AIM-1, the sequence analysis also indicated that MIM-1 and MIM-2 share similarities with N-acyl homoserine lactonases (AHLases) and glyoxalase II (GLX-II). Steady-state kinetic assays using a series of lactone substrates confirm that MIM-1 and MIM-2 are efficient lactonases, with catalytic efficiencies resembling those of well-known AHLases. Interestingly, unlike their MBL activity the AHLase activity of MIM-1 and MIM-2 is not dependent on the metal ion composition with Zn(II), Co(II), Cu(II), Mn(II) and Ca(II) all being able to reconstitute catalytic activity (with Co(II) being the most efficient). However, these enzymes do not turn over S-lactoylglutathione, a substrate characteristic for GLX-II activity. Since lactonase activity is linked to the process of quorum sensing the bifunctional activity of “non-pathogenic” MBLs such as MIM-1 and MIM-2 may provide insight into one possible evolutionary pathway for the emergence of antibiotic resistance

β-Lactam antibiotic-degrading enzymes from non-pathogenic marine organisms: a potential threat to human health

Metallo-beta-lactamases (MBLs) are a family of Zn(II)-dependent enzymes that inactivate most of the commonly used beta-lactam antibiotics. They have emerged as a major threat to global healthcare. Recently, we identified two novel MBL-like proteins, Maynooth IMipenemase-1 (MIM-1) and Maynooth IMipenemase-2 (MIM-2), in the marine organisms Novosphingobium pentaromativorans and Simiduia agarivorans, respectively. Here, we demonstrate that MIM-1 and MIM-2 have catalytic activities comparable to those of known MBLs, but from the pH dependence of their catalytic parameters it is evident that both enzymes differ with respect to their mechanisms, with MIM-1 preferring alkaline and MIM-2 acidic conditions. Both enzymes require Zn(II) but activity can also be reconstituted with other metal ions including Co(II), Mn(II), Cu(II) and Ca(II). Importantly, the substrate preference of MIM-1 and MIM-2 appears to be influenced by their metal ion composition. Since neither N. pentaromativorans nor S. agarivorans are human pathogens, the precise biological role(s) of MIM-1 and MIM-2 remains to be established. However, due to the similarity of at least some of their in vitro functional properties to those of known MBLs, MIM-1 and MIM-2 may provide essential structural insight that may guide the design of as of yet elusive clinically useful MBL inhibitors

Use of magnetic circular dichroism to study dinuclear metallohydrolases and the corresponding biomimetics

Magnetic circular dichroism (MCD) is a convenient technique for providing structural and mechanistic insight into enzymatic systems in solution. The focus of this review is on aspects of geometric and electronic structure that can be determined by MCD, and how this method can further our understanding of enzymatic mechanisms. Dinuclear Co(II) systems that catalyse hydrolytic reactions were selected to illustrate the approach. These systems all contain active sites with similar structures consisting of two Co(II) ions bridged by one or two carboxylates and a water or hydroxide. In most of these active sites one Co(II) is five-coordinate and one is six-coordinate, with differing binding affinities. It is shown how MCD can be used to determine which binding site—five or six-coordinate—has the greater affinity. Importantly, zero-field-splitting data and magnetic exchange coupling constants may be determined from the temperature and field dependence of MCD data. The relevance of these data to the function of the enzymatic systems is discussed

Rapid-Freeze-Quench Magnetic Circular Dichroism of Intermediate X in Ribonucleotide Reductase: New Structural Insight

To elucidate the electronic structure of intermediate X in the oxygen activation reaction of the R2 subunit of ribonucleotide reductase, a protocol has been developed to perform magnetic circular dichroism (MCD) on a rapid-freeze-quench, strain free optical sample. RFQ-MCD data have been collected on intermediate X in the double mutant of R2, Y122/Y356F. While X has been reported to exhibit a broad absorption band at 365 nm, there are at least 10 electronic transitions observed at low-temperature MCD. From C0/D0 ratios, the transitions of X can be divided into three regions: 16 000-22 000 cm-1 region involving spin-allowed ligand field transitions of the Fe(IV), 23 000-24 000 cm-1 region of spin-forbidden, spin-flip transitions on the Fe(IV), and the charge transfer (CT) region from 26 000 to 32 000 cm-1. The C0/D0 ratios from d --> d and CT transitions strongly support significant Fe(IV) character coupled into the paramagnetic center. Ligand field (spin-allowed d --> d region) analysis allows the bis-mu-oxo and mu-oxo plus other monoanionic bridge possibilities for the structure of intermediate X to be distinguished, providing new insight into the molecular mechanism of the cluster formation in R2