Background: Polysaccharide intercellular adhesin-dependent biofilm formation in E. coli requires the de-N-acetylation of poly-␤-1,6-N-acetyl-D-glucosamine by PgaB. Results: Nickel-and iron-bound structures of PgaB have been determined, and the metal-dependent de-N-acetylase activity of the enzyme has been characterized. Conclusion: PgaB has low catalytic efficiency and shows preference for Co 2ϩ , Ni 2ϩ , and Fe 2ϩ ions. Significance: The structure of PgaB will guide inhibitor design to combat biofilm formation.

A polymer of partially de-N-acetylated β-1,6-linked N-acetylglucosamine (dPNAG), also known as the polysaccharide intercellular adhesin (PIA), is an important component of many bacterial biofilm matrices. In Staphyloccocus epidermidis, the poly-N-acetylglucosamine polymer is partially de-N-acetylated by the extracellular protein IcaB. To understand the mechanism of action of IcaB, the enzyme was overexpressed and purified. IcaB demonstrates metal-dependent de-N-acetylase activity on β-1,6-linked N-acetylglucosamine oligomers with a broad preference for divalent metals. Steady-state kinetic analysis reveals the low catalytic efficiency (pentasaccharide kcat/KM 0.03 M(-1) s(-1)) of the enzyme toward the oligomeric substrates. While IcaB displays similar rates of de-N-acetylation with tri- through hexasaccharide PNAG oligomers, position specific de-N-acetylation was only observed with penta- and hexasaccharides. The enzyme preferentially de-N-acetylates the second residue from the reducing terminus in the pentasaccharide and second and third residues from the reducing terminus in the hexasaccharide. The data described here represent an important step toward a detailed understanding of dPNAG biosynthesis in S. epidermidis, an important nosocomial pathogen, as well as in other Gram-positive bacteria. The low catalytic activity of IcaB is consistent with reports of other enzymes which act on biofilm-related polysaccharides, and this emerging trend may indicate a common feature among this group of polysaccharide processing enzymes.

Many medically important biofilm forming bacteria produce similar polysaccharide intercellular adhesins (PIA) consisting of partially de-N-acetylated β-(1 → 6)-N-acetylglucosamine polymers (dPNAG). In Escherichia coli, de-N-acetylation of the β-(1 → 6)-N-acetylglucosamine polymer (PNAG) is catalysed by the carbohydrate esterase family 4 deacetylase PgaB. The de-N-acetylation of PNAG is essential for productive PNAG-dependent biofilm formation. Here, we describe the development of a fluorogenic assay to monitor PgaB activity in vitro and the synthesis of a series of PgaB inhibitors. The synthesized inhibitors consist of a metal chelating functional group on a glucosamine scaffold to target the active site metal ion of PgaB. Optimal inhibition was observed with N-thioglycolyl amide (K(i) = 480 μM) and N-methyl-N-glycolyl amide (K(i) = 320 μM) glucosamine derivatives. A chemoenzymatic synthesis of an N-thioglycolyl amide PNAG pentasaccharide led to an inhibitor with an improved K(i) of 280 μM.

The occurrence of two butenolides, menisdaurilide and aquilegiolide, in commercial specimens of Dicentra spectabilis is reported for the first time; a rapid and direct isolation protocol is described. The ability of these lactones to induce apoptosis in human tumour cell lines at 10 microM concentration is also described. The high abundance and apoptosis-inducing activity reported here indicates that these constituents play a more significant role than the hormonal action previously attributed to them.

Open Life Sci. 2015; 10: 546-553 day I, correlated well to vaspin concentrations (r 2 = 0.201, p = 0.011). ATP levels were significantly lower in patients vs. controls (day I: p = 0.00012; day IV: p = 0.0001). Conclusions: Changes in the analyzed visfatin and vaspin concentrations can be used as potential MI markers. Visfatin serum concentration may be considered a potential marker to differentiate MI over time.Keywords: myocardial infarction, visfatin, vaspin, adenine nucleotides, uric acid IntroductionAdipocytokines are a large group of bioactive proteins and they manifest hormone-like attributes with properites similar to some chemokines, cytokines and growth factors. Specific changes in the circulatory levels of adipokines appear to have a proatherogenic, proinflammatory and anti-insulin effects on human cells [1].Visfatin is an adipokine mainly expressed in visceral fat tissue, and is also produced in the myocardium, bone marrow, skeletal muscle, and liver [2]. Visfatin occurs in a form of a dimer, capable of binding and hydrolyzing ATP. Visfatin undergoes self-phosphorylation which enhances its catalytic function in nicotinate and nicotinamide metabolism [2]. Increased visfatin serum levels were found in some diseases associated with obesity, atherogenesis and insulin-resistance [3]. Visfatin has been considered as a pro-inflammatory factor and is also associated with vascular smooth muscle cell maturation and plaque destabilization [2,4]. The plasma visfatin level was found to be elevated in patients with acute ST-segment elevation myocardial infarction (STEMI) [5].Vaspin, identified in 2005, is a serine protease inhibitor secreted only by visceral fat tissue [6]. In animal models, it has been shown that vaspin enhances insulin sensitivity in peripheral tissues thus improving glucose tolerance, Abstract: Introduction: The association of vaspin and visfatin, with a myocardial infarction is still not fully understood. Reduced levels of adenine nucleotides are hallmarks of chronic heart failure. There is little data concerning the relationship between these markers and their changes over time. Material/Methods: The concentration of adenine nucleotides, vaspin and visfatinwere assessed in 41 consecutive patients with acute myocardial infarction one before (day I) and four days after (day IV) percutaneous coronary intervention (PCI) and a control group. Results: Visfatin concentrations were higher before and after PCI vs. control (visfatin I: median 25.55, visfatin IV: median 20.79,.61 ng/ml vs. control: median 14.94, 10.66 -25.25 ng/ml; p < 0.0001). Vaspin concentrations were lower before and after PCI vs. control (vaspin I: median 0.18, 0.11 -0.44 ng/ml; vaspin IV: median 0.24, 0.15 -0.58 ng/ml vs. control: median 1.303, 1.13 -2.26 ng/ml, p < 0.00001). Concentrations of visfatin,