This article explores why women delay childbearing and increase their likelihood to remain childless in Spain, Italy, West Germany and France. We take a macro-micro perspective and show that national institutions influence women's life transitions, in particular partnership and motherhood. For coupled women, we find two alternative modes out of childlessness. In countries with high direct and indirect child costs, like Spain and Italy, entering a male-breadwinner couple or occupying a stable and high-income position facilitates motherhood, while in the French context motherhood is most likely in a dual-earner partnership.Keywords Childlessness AE family formation AE European comparative analysis Ré sumé: Cet article explore les raisons pour lesquelles les femmes retardent la procré ation au risque de ne pas avoir d'enfants, en Espagne, Italie, Allemagne de l'Ouest et France. A l'aide d'une perspective macro-micro, nous dé montrons que les politiques nationales influencent les transitions dans la vie des femmes, et notamment la mise en couple et la maternité . Pour les femmes en couple, il y a deux façons de faire la transition vers le premier enfant. Dans les pays où les coû ts directs et indirects de l'enfant sont é levé s, comme l'Italie et l'Espagne, le fait de devenir femme au foyer avec un conjoint qui travaille, ou encore d'occuper une position professionnelle stable et bien ré muné ré e facilite la maternité , alors que dans le contexte de la France, la maternité est plus probable dans le cadre de couples bi-actifs.Mots-clés non-maternité AE formation des familles AE perspective comparative europé enne M.-J. Gonzá lez Departament de Ciè ncies Polítiques i Socials, UPF, Edifici Jaume I -Ramon Trias Fargas, 25-27,
15N longitudinal relaxation rates are extensively used for the characterization of protein dynamics; however, their accurate measurement is hindered by systematic errors. 15N CSA/1H–15N dipolar cross-correlated relaxation (CC) and amide proton exchange saturation transfer from water protons are the two main sources of systematic errors in the determination of 15N R1 rates through 1H–15N HSQC-based experiments. CC is usually suppressed through a train of 180° proton pulses applied during the variable 15N relaxation period (T), which can perturb water magnetization. Thus CC cancellation is required in such a way as to minimize water saturation effects. Here we examined the level of water saturation during the T period caused by various types of inversion proton pulses to suppress CC: (I) amide-selective IBURP-2; (II) cosine-modulated IBURP-2; (III) Watergate-like blocks; and (IV) non-selective hard. We additionally demonstrate the effect of uncontrolled saturation of aliphatic protons on 15N R1 rates. In this paper we present an optimized pulse sequence that takes into account the crucial effect of controlling also the saturation of the aliphatic protons during 15N R1 measurements in non-deuterated proteins. We show that using cosine-modulated IBURP-2 pulses spaced 40 ms to cancel CC in this optimized pulse program is the method of choice to minimize systematic errors coming from water and aliphatic protons saturation effects.Electronic supplementary materialThe online version of this article (doi:10.1007/s10858-015-9937-4) contains supplementary material, which is available to authorized users.
A peptide fragment corresponding to the third helix of Staphylococcus Aureus protein A, domain B, was chosen to study the effect of the main-chain direction upon secondary structure formation and stability, applying the retro-enantio concept. For this purpose, two peptides consisting of the native (Ln) and reversed (Lr) sequences were synthesized and their conformational preferences analysed by CD and NMR spectroscopy. A combination of CD and NMR data, such as molar ellipcitity. NOE connectivities, H alpha and NH chemical shifts, 3J alpha N coupling constants and amide temperature coefficients indicated the presence of nascent helices for both Ln and Lr in water, stabilized upon addition of the fluorinated solvents TFE and HFIP. Helix formation and stabilization appeared to be very similar in both normal and retro peptides, despite the unfavourable charge-macrodipole interactions and bad N-capping in the retro peptide. Thus, these helix stabilization factors are not a secondary structure as determined for this specific peptide. In general, the synthesis and confirmational analysis of peptide pairs with opposite main-chain directions, normal and retro peptides, could be useful in the determination of secondary structure stabilization factors dependent on the direction.
A peptide fragment corresponding to the third helix of Staphylococcus Aureus protein A, domain B, was chosen to study the effect of the main-chain direction upon secondary structure formation and stability, applying the retro-enantio concept. For this purpose, two peptides consisting of the native (Ln) and reversed (Lr) sequences were synthesized and their conformational preferences analysed by CD and NMR spectroscopy. A combination of CD and NMR data, such as molar ellipcitity. NOE connectivities, H alpha and NH chemical shifts, 3J alpha N coupling constants and amide temperature coefficients indicated the presence of nascent helices for both Ln and Lr in water, stabilized upon addition of the fluorinated solvents TFE and HFIP. Helix formation and stabilization appeared to be very similar in both normal and retro peptides, despite the unfavourable charge-macrodipole interactions and bad N-capping in the retro peptide. Thus, these helix stabilization factors are not a secondary structure as determined for this specific peptide. In general, the synthesis and confirmational analysis of peptide pairs with opposite main-chain directions, normal and retro peptides, could be useful in the determination of secondary structure stabilization factors dependent on the direction.
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