Search results for "Triad"

Stimuli-Responsive Tertiary Amine Functional PEGs Based on N,N-Dialkylglycidylamines

2014

Amine-functional poly(ethylene glycol) (PEG) copolymers have been prepared that exhibit thermo- and pH- responsive behavior in aqueous solution. Three novel tertiary di(n-alkyl)glycidylamine monomers have been introduced for anionic ring-opening copolymerization (AROcP) with ethylene oxide (EO): N,N-di(n-butyl)glycidylamine (DButGA), N,N-di(n-hexyl)glycidylamine (DHexGA), and N,N-di(n-octyl)glycidylamine (DOctGA). Via controlled AROcP we synthesized well-defined (Mw/Mn = 1.05–1.14), water-soluble block- and gradient-type PEG copolymers, containing up to 25 mol % of the respective dialkylglycidylamine comonomer. Molecular weights ranged from 4900 to 12 000 g mol–1. Detailed in-situ 1H NMR ki…

Letter in response to “ COVID ‐19, Virchow's triad and thromboembolic risk in obese pregnant women”

2021

Structural Basis and Enzymatic Mechanism of the Biosynthesis of C9- from C10-Monoterpenoid Indole Alkaloids

2009

Cutting carbons: The three-dimensional structure of polyneuridine aldehyde esterase (PNAE) gives insight into the enzymatic mechanism of the biosynthesis of C(9)- from C(10)-monoterpenoid indole alkaloids (see scheme). PNAE is a very substrate-specific serine esterase. It harbors the catalytic triad S87-D216-H244, and is a new member of the alpha/beta-fold hydrolase superfamily. Its novel function leads to the diversification of alkaloid structures.

Copper-, cobalt-, and manganese-containing 17-tungsto-2-germanates.

2009

The sandwich-type tungstogermanates [Cu(3)(H(2)O)(B-beta-GeW(9)O(33)(OH))(B-beta-GeW(8)O(30)(OH))](12-) (1), [Co(H(2)O)(2){Co(3)(B-beta-GeW(9)O(33)(OH))(B-beta-GeW(8)O(30)(OH))}(2)](22-) (2), and [Mn(H(2)O)(2){Mn(3)(H(2)O)(B-beta-GeW(9)O(33)(OH))(B-beta-GeW(8)O(30)(OH))}(2)](22-) (3) were synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, and infrared spectroscopy. Polyanion 1 is composed of two nonequivalent Keggin units, (B-beta-GeW(8)O(31)) and (B-beta-GeW(9)O(34)), linked to each other via three copper(II) ions in such a way that there is a plane of symmetry passing through both Ge atoms and the unique Cu atom, resulting in…

The association between achievement goal motivation and counterproductive work behavior: the moderating effect of work engagement and the Dark Triad

2020

BackgroundThe objective of the article is to describe the association between counterproductive work behavior (CWB), achievement goal motivation and the moderating variables: work engagement and the Dark Triad (DT). The theoretical bases of the tested models are: the four-factor theory of achievement goal motivation (Elliot & McGregor), the CWB conception of Spector, the JD-R model of Demerouti, the work engagement model of Schaufeli and the DT conception of Paulhus and Williams.Participants and procedureAn internet study was conducted with 138 office employees as participants. The variables were measured us-ing the Polish versions of the following tools: achievement goal motivation – A…

Potential active-site residues in polyneuridine aldehyde esterase, a central enzyme of indole alkaloid biosynthesis, by modelling and site-directed m…

2002

In the biosynthesis of the antiarrhythmic alkaloid ajmaline, polyneuridine aldehyde esterase (PNAE) catalyses a central reaction by transforming polyneuridine aldehyde into epi-vellosimine, which is the immediate precursor for the synthesis of the ajmalane skeleton. The PNAE cDNA was previously heterologously expressed in E. coli. Sequence alignments indicated that PNAE has a 43% identity to a hydroxynitrile lyase from Hevea brasiliensis, which is a member of the α/β hydrolase superfamily. The catalytic triad, which is typical for this family, is conserved. By site-directed mutagenesis, the members of the catalytic triad were identified. For further detection of the active residues, a model…

N,N-Diallylglycidylamine: A Key Monomer for Amino-Functional Poly(ethylene glycol) Architectures

2012

The first application of N,N-diallylglycidylamine (DAGA) as a monomer for anionic ring-opening polymerization is presented. The monomer is obtained in a one-step procedure using epichlorohydrin and N,N-diallylamine. Both random and block copolymers consisting of poly(ethylene glycol) and poly(N,N-diallylglycidylamine) with adjusted DAGA ratios from 2.5 to 24% have been prepared, yielding well-defined materials with low polydispersities (Mw/Mn) in the range 1.04–1.19. Molecular weights ranged between 2600 and 10 300 g mol–1. Isomerization of allylamine to enamine structures during polymerization depending on time, temperature, and counterion has been realized. The kinetics of the formation o…

Catalytic triad of microsomal epoxide hydrolase: replacement of Glu404 with Asp leads to a strongly increased turnover rate

1998

Microsomal epoxide hydrolase (mEH) belongs to the superfamily of α/β-hydrolase fold enzymes. A catalytic triad in the active centre of the enzyme hydrolyses the substrate molecules in a two-step reaction via the intermediate formation of an enzyme-substrate ester. Here we show that the mEH catalytic triad is composed of Asp226, Glu404 and His431. Replacing either of these residues with non-functional amino acids results in a complete loss of activity of the enzyme recombinantly expressed in Saccharomyces cerevisiae. For Glu404 and His431 mutants, their structural integrity was demonstrated by their retained ability to form the substrate ester intermediate, indicating that the lack of enzymi…

Psychometric properties and validation of the Polish adaptation of the Light Triad Scale

2019

BackgroundThe aim of the study was to examine the development and structural validation of the Polish version of the Light Triad Scale, which measures three factors: Faith in Humanity, Humanism, and Kantianism. This tool reflects caring and beneficent orienta-tion toward other people, which is demonstrated in everyday behaviour.Participants and procedureThe participants included 400 people aged between 18 and 80 (M = 29.17, SD = 10.60). To measure psychometric properties and for validation of the scale, we used the Polish Dirty Dozen scale and International Personality Item Pool-Big Five Aspect Scales.ResultsConfirmatory factor analysis, reliability analysis using α and ω coefficients, and …

Peirce i Wittgenstein o życiu znaków

2014

Celem tego artykułu jest zbadanie i porównanie poglądów Peirce'a i Wittgensteina na naturę znaków. Przeprowadzone badanie pokazuje, że istnieją przynajmniej cztery punkty w powyższej kwestii, co do których Peirce i Wittgenstein pozostają zgodni: triadyczna natura znaków, obecność i szczególna rola w naszych dyskursach znaków zdegenerowanych, rola reguł w konstytuowaniu znaczenia znaków, a także niezbywalna rola społeczności w tworzeniu i podtrzymywaniu procesu semiozy. Fakt istnienia znaczących podobieństw w poglądach Peirce'a i Wittgensteina na naturę znaków nie sprawia jednak, że ich koncepcje semiotyczne są identyczne. Koncepcje te opierają się bowiem na odmiennych założeniach np. co do …