title: US-SOMOHPLC-SAXS module: dealing with capillary fouling and extraction of pure component patterns from poorly resolved SEC-SAXS data.
abstract: Size-exclusion chromatography coupled with SAXS (small-angle X-ray scattering), often performed using a flow-through capillary, should allow direct collection of monodisperse sample data. However, capillary fouling issues and non-baseline-resolved peaks can hamper its efficacy. TheUltraScansolution modeler (US-SOMO) HPLC-SAXS (high-performance liquid chromatography coupled with SAXS) module provides a comprehensive framework to analyze such data, starting with a simple linear baseline correction and symmetrical Gaussian decomposition tools [Brookes, Pérez, Cardinali, Profumo, Vachette & Rocco (2013 ▸).J. Appl. Cryst.46, 1823-1833]. In addition to several new features, substantial improvements to both routines have now been implemented, comprising the evaluation of outcomes by advanced statistical tools. The novel integral baseline-correction procedure is based on the more sound assumption that the effect of capillary fouling on scattering increases monotonically with the intensity scattered by the material within the X-ray beam. Overlapping peaks, often skewed because of sample interaction with the column matrix, can now be accurately decomposed using non-symmetrical modified Gaussian functions. As an example, the case of a polydisperse solution of aldolase is analyzed: from heavily convoluted peaks, individual SAXS profiles of tetramers, octamers and dodecamers are extracted and reliably modeled.
authors.affiliation: Department of Biochemistry, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3901, USA.
authors.forename: Emre
authors.initials: E
authors.lastname: Brookes
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, F-91198, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Vachette
authors.affiliation: Biopolimeri e Proteomica, IRCCS AOU San Martino-IST, Istituto Nazionale per la Ricerca sul Cancro, Largo R. Benzi 10, Genova, I-16132, Italy.
authors.forename: Mattia
authors.initials: M
authors.lastname: Rocco
authors.affiliation: SWING Beamline, Synchrotron SOLEIL, L'Orme des Merisiers, BP48, Saint-Aubin, Gif-sur-Yvette, F-91192, France.
authors.forename: Javier
authors.initials: J
authors.lastname: Pérez
keywords: CorMap analysis; P-value analysis; US-SOMO HPLC-SAXS module; aldolase supramolecular complexes; asymmetric modified Gaussian decomposition; multi-resolution modeling; poorly resolved chromatographic peaks