ABSTRACT
Experimental information from small angle X-ray scattering (SAXS) is conjugated with nuclear magnetic resonance (NMR) spectroscopy data for the improvement of protein structure determination, particularly for flexible, multidomain or intrinsically disordered proteins. Individually, each of these techniques presents capabilities and limitations: NMR excels in local information, providing atomic resolution, but is limited by protein size, whereas SAXS yields a global envelope of the protein with lower resolution, but revealing domain positions. Different conjugation methodologies use the complementarity of both techniques' independent constraints to achieve comprehensive protein structure determination and resolve dynamics at a moderate computational expense.
Subject(s)
Intrinsically Disordered Proteins/chemistry , Magnetic Resonance Spectroscopy/methods , X-Ray Diffraction/methods , Algorithms , Computer Simulation , Models, Molecular , Protein Conformation , Scattering, Small AngleABSTRACT
Abstract Experimental information from small angle X-ray scattering (SAXS) is conjugated with nuclear magnetic resonance (NMR) spectroscopy data for the improvement of protein structure determination, particularly for flexible, multidomain or intrinsically disordered proteins. Individually, each of these techniques presents capabilities and limitations: NMR excels in local information, providing atomic resolution, but is limited by protein size, whereas SAXS yields a global envelope of the protein with lower resolution, but revealing domain positions. Different conjugation methodologies use the complementarity of both technique´s independent constraints to accomplish a comprehensive protein structure determination and dynamics understanding at a moderate computational expense.
Resumen Se conjuga información experimental proveniente de dispersión de rayos X a ángulos pequeños (SAXS) con la espectroscopía de resonancia magnética nuclear (NMR) para perfeccionar la determinación de la estructura protéica, en particular de proteínas flexibles, de multidominio o intrínsecamente desordenadas. Individualmente, cada una de estas técnicas presenta capacidades y limitaciones: NMR se destaca en la información local, proporcionando resolución atómica, pero está limitada por el tamaño de la proteína, mientras que SAXS produce una envoltura global de la proteína con una resolución menor pero revelando las posiciones de los dominios. Las diferentes metodologías de conjugación utilizan la complementariedad de las restricciones independientes de ambas técnicas para seguir estrategias adecuadas de acuerdo con la proteína, logrando una determinación integral de la estructura y una comprensión de las dinámicas del sistema proteico a un costo computacional moderado.
ABSTRACT
The immobilization of individual biological molecules by metal nanoparticles requires that the particles themselves be immobilized. We introduce a new technique for immobilization of gold clusters based on their binding to small tunnels in a graphite support, themselves created by the implantation of small clusters. These tunnels are shown to perform as more effective cluster immobilization sites than point defects on the surface of graphite. The method is tested with atomic force microscopy (AFM) (both contact and noncontact mode) scanning. Size-selected clusters with 923, 561, 309, and 147 atoms have been immobilized and imaged with high-resolution, noncontact AFM.
