1,720,962 research outputs found
DETERMINATION OF (3)J(H-I(N),C-I(')) COUPLING-CONSTANTS IN PROTEINS WITH THE C'-FIDS METHOD
No full textWe introduce the C'-FIDS-H-1, N-15-HSQC experiment: a new method for the determination of (3)J(H-i(N), C-i) coupling constants in proteins, yielding information about the torsional angle phi. It relies on the H-1, N-15-HSQC or HNCO experiment, two of the the most sensitive heteronuclear correlation experiments for isotopically labeled proteins. A set of three H-1, N-15-HSQC or HNCO spectra are recorded: a reference experiment in which the carbonyl spins are decoupled during t(1) and t(2), a second experiment in which they are decoupled exclusively during t(1) and a third one in which they are coupled in t(1), as well as t(2). The last experiment yields an E.COSY-type pattern from which the (2)J(HNiN, C-i-1) and (1)J(N-i, C-i-1) coupling constants can be extracted. By comparison of the coupled multiplet (obtained from the second experiment) with the decoupled multiplet (obtained from the first experiment) convoluted with the (2)J(H-i(N), C-i-1) coupling, the (3)J(HN:CI) coupling can be found in a one-parameter fitting procedure. The method is demonstrated for the protein rhodniin, containing 103 amino acids. Systematic errors due to differential relaxation are small for (n)J(H-N, C-n) couplings in biomacromolecules of the size currently under NMR spectroscopic investigation
DETERMINATION OF (3)J(H-I(N),C-I(')) COUPLING-CONSTANTS IN PROTEINS WITH THE C'-FIDS METHOD
No full textWe introduce the C'-FIDS-H-1, N-15-HSQC experiment: a new method for the determination of (3)J(H-i(N), C-i) coupling constants in proteins, yielding information about the torsional angle phi. It relies on the H-1, N-15-HSQC or HNCO experiment, two of the the most sensitive heteronuclear correlation experiments for isotopically labeled proteins. A set of three H-1, N-15-HSQC or HNCO spectra are recorded: a reference experiment in which the carbonyl spins are decoupled during t(1) and t(2), a second experiment in which they are decoupled exclusively during t(1) and a third one in which they are coupled in t(1), as well as t(2). The last experiment yields an E.COSY-type pattern from which the (2)J(HNiN, C-i-1) and (1)J(N-i, C-i-1) coupling constants can be extracted. By comparison of the coupled multiplet (obtained from the second experiment) with the decoupled multiplet (obtained from the first experiment) convoluted with the (2)J(H-i(N), C-i-1) coupling, the (3)J(HN:CI) coupling can be found in a one-parameter fitting procedure. The method is demonstrated for the protein rhodniin, containing 103 amino acids. Systematic errors due to differential relaxation are small for (n)J(H-N, C-n) couplings in biomacromolecules of the size currently under NMR spectroscopic investigation
Determination of HN,Hα and HN,C′ coupling constants in 13C, 15N-labeled proteins
No full textSensitive three-dimensional NMR experiments, based on the E.COSY principle, are presented for the measurement of the 3J(HN,Hα) and 3J(HN,C′) coupling constants in uniformly 13C- and 15N-labeled proteins. They employ gradient coherence selection in combination with the sensitivity enhancement method in HSQC-type spectra (Cavanagh et al., 1991; Palmer et al., 1991). In most cases, the two measured coupling constants unambiguously define the ϕ-angle for protein structure determination. The method is applied to uniformly 13C, 15N-labeled ribonuclease T1
DETERMINATION OF H(N),H-ALPHA AND H(N), C' COUPLING-CONSTANTS IN C-13,N-15-LABELED PROTEINS
No full textSensitive three-dimensional NMR experiments, based on the E.COSY principle, are presented for the measurement of the 3J(H(N),H(alpha) and 3J(H(N),C') coupling constants in uniformly C-13- and N-15-labeled proteins. They employ gradient coherence selection in combination with the sensitivity enhancement method in HSQC-type spectra (Cavanagh et al., 1991; Palmer et al., 1991). In most cases, the two measured coupling constants unambiguously define the phi-angle for protein structure determination. The method is applied to uniformly C-13,N-15-labeled ribonuclease T1
Determination of 3J(H infi supN ,C infi sup? ) coupling constants in proteins with the C?-FIDS method
No full textWe introduce the C′-FIDS-1H,15N-HSQC experiment, a new method for the determination of 3J(H infi supN ,C infi sup′ ) coupling constants in proteins, yielding information about the torsional angle ϕ. It relies on the 1H,15N-HSQC or HNCO experiment, two of the the most sensitive heteronuclear correlation experiments for isotopically labeled proteins. A set of three 1H,15N-HSQC or HNCO spectra are recorded: a reference experiment in which the carbonyl spins are decoupled during t1 and t2, a second experiment in which they are decoupled exclusively during t1 and a third one in which they are coupled in t1 as well as t2. The last experiment yields an E.COSY-type pattern from which the 2J(H infi supN ,C infi-1 sup′ ) and 1J(Ni,C infi-1 sup′ ) coupling constants can be extracted. By comparison of the coupled multiplet (obtained from the second experiment) with the decoupled multiplet (obtained from the first experiment) convoluted with the 2J(H infi supN ,C infi-1 sup′ ) coupling, the 3J(H infi supN ,C infi sup′ ) coupling can be found in a one-parameter fitting procedure. The method is demonstrated for the protein rhodniin, containing 103 amino acids. Systematic errors due to differential relaxation are small for nJ(HN,C′) couplings in biomacromolecules of the size currently under NMR spectroscopic investigation
DETERMINATION OF H(N),H-ALPHA AND H(N), C' COUPLING-CONSTANTS IN C-13,N-15-LABELED PROTEINS
No full textSensitive three-dimensional NMR experiments, based on the E.COSY principle, are presented for the measurement of the 3J(H(N),H(alpha) and 3J(H(N),C') coupling constants in uniformly C-13- and N-15-labeled proteins. They employ gradient coherence selection in combination with the sensitivity enhancement method in HSQC-type spectra (Cavanagh et al., 1991; Palmer et al., 1991). In most cases, the two measured coupling constants unambiguously define the phi-angle for protein structure determination. The method is applied to uniformly C-13,N-15-labeled ribonuclease T1
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
