Gu?a r?pidas de consultor?a telef?nica m?dica y de enfermer?a

Gu?a de consulta para o persoal m?dico e de enfermar?a que desenvolve o seu traballo en centros de coordinaci?n telef?nica para a atenci?n ?s urxencias e ?s emerxencias sanitarias. Est? estruturada en 12 cap?tulos nos que describen os principais protocolos de actuaci?n para a asistencia ?s patolox?as m?is com?ns atendidas no ?mbito de urxencias extra hospitalarias.Gu?a de consulta para el personal m?dico y de enfermer?a que desarrolla su trabajo en centros de coordinaci?n telef?nica para la atenci?n a las urgencias y a las emergencias sanitarias. Est? estructurada en 12 cap?tulos en los que describen los principales protocolos de actuaci?n para la asistencia a las patolog?as m?s comunes atendidas en el ?mbito de urgencias extra hospitalarias

X-ray free-electron laser studies reveal correlated motion during isopenicillin N synthase catalysis.

Isopenicillin N synthase (IPNS) catalyzes the unique reaction of l-δ-(α-aminoadipoyl)-l-cysteinyl-d-valine (ACV) with dioxygen giving isopenicillin N (IPN), the precursor of all natural penicillins and cephalosporins. X-ray free-electron laser studies including time-resolved crystallography and emission spectroscopy reveal how reaction of IPNS:Fe(II):ACV with dioxygen to yield an Fe(III) superoxide causes differences in active site volume and unexpected conformational changes that propagate to structurally remote regions. Combined with solution studies, the results reveal the importance of protein dynamics in regulating intermediate conformations during conversion of ACV to IPN. The results have implications for catalysis by multiple IPNS-related oxygenases, including those involved in the human hypoxic response, and highlight the power of serial femtosecond crystallography to provide insight into long-range enzyme dynamics during reactions presently impossible for nonprotein catalysts

An on-demand, drop-on-drop method for studying enzyme catalysis by serial crystallography

Serial femtosecond crystallography has opened up many new opportunities in structural biology. In recent years, several approaches employing light-inducible systems have emerged to enable time-resolved experiments that reveal protein dynamics at high atomic and tem poral resolutions. However, very few enzymes are light-dependent, whereas macromolecules requiring ligand diffusion into an active site are ubiquitous. In this work we present a drop-on drop sample delivery system that enables the study of enzyme-catalyzed reactions in microcrystal slurries. The system delivers ligand solutions in bursts of multiple picoliter-sized drops on top of a larger crystal-containing drop inducing turbulent mixing and transports the mixture to the X-ray interaction region with temporal resolution. We demonstrate mixing using fluorescent dyes, numerical simulations and time-resolved serial femtosecond crys tallography, which show rapid ligand diffusion through microdroplets. The drop-on-drop method has the potential to be widely applicable to serial crystallography studies, particularly of enzyme reactions with small molecule substrates