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In its 88-year story, the mission of our institute has been to carry out excellence research in fundamental and applied physical chemistry, contributing to the scientific training of several generations of researchers at the highest level. Our vision is to be an international reference in multidisciplinary research focused on the resolution of the present challenges of our society in the fields of health, biotechnology, new materials, and environment.



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Figure-4A small

Bacterial cell wall is a polymer of considerable complexity that is in constant equilibrium between synthesis and recycling. AmpDh3 is a periplasmic zinc protease of Pseudomonas aeruginosa, which is intimately involved in cell-wall remodeling. In this report we document the reactions that this enzyme performs on the cell wall, which hydrolyze the peptide stems from the peptidoglycan, the major constituent of the cell wall. We document that the majority of the reactions of this enzyme takes place on the polymeric insoluble portion of the cell wall, as opposed to the fraction that is released from it. We show that AmpDh3 is tetrameric both in crystals and in solution. Based on the X-ray structures of the enzyme in complex with two synthetic cell-wall-based ligands, we present for the first time a model for a multivalent anchoring of AmpDh3 onto the cell wall, which lends itself to its processive remodeling.




Lee, M.; Artola-Recolons, C.; Carrasco-López, C.; Martínez-Caballero, S.; Hesek, D.; Spink, E.; Lastochkin, E.; Zhang, W.; Hellman, L.; Boggess, B.; Hermoso*, J.; Mobashery*, S.

      Cell-Wall Remodeling by the Zinc-Protease AmpDh3 from Pseudomonas aeruginosa

      J. Am. Chem. Soc. 2013; 12605-12607.


ampdh2-verybigThe zinc protease AmpDh2 is a virulence determinant of Pseudomonas aeruginosa, a problematic human pathogen. The mechanism of how the protease manifests virulence is not known, but it is known that it turns over the bacterial cell wall. A research conducted by the Instituto de Química-Física Rocasolano and the University of Notre Dame (Indiana, USA) provided insights into the mechanism of action of AmpDh2. The reaction of AmpDh2 with the cell wall was investigated and nine distinct turnover products were characterized by LC/MS/MS. The enzyme turns over both the crosslinked and non-crosslinked cell wall. Three high-resolution X-ray structures, of the apo enzyme and of two complexes with turnover products, were solved. The X-ray structures show how the dimeric protein interacts with the inner leaflet of the bacterial outer membrane and that the two monomers provide a more expansive surface for recognition of the cell wall. This binding surface can accommodate the three-dimensional solution structure of the crosslinked cell wall. We have disclosed in this report the nature of the reactions of AmpDh2 with the bacterial sacculus and have determined the structure of the protein, which reveals the importance of the dimeric nature in accommodating larger segments of the cell wall. The present study reveals at atomic detail the structural attributes of this important virulence factor of P. areruginosa in the reactions that it performs, which are at the roots of the manifestation of the virulence.


Siseth Martínez-Caballero, Mijoon Lee, Cecilia Artola-Recolons, César Carrasco-López, Dusan Hesek, Edward Spink, Elena Lastochkin, Weilie Zhang, Lance M. Hellman, Bill Boggess, Shahriar Mobashery* and Juan A. Hermoso*

Reaction products and the X-ray structure of AmpDh2, a virulence determinant of Pseudomonas aeruginosa.

Journal of the American Chemical Society (2013) 135, - (in press)  (doi:10.1021/ja405464b)

Generación, caracterización y control de plasmas de ablación láser

Wednesday, July 3rd 2013

12:00 Salón de Actos

Oxide surfaces are usually considered to be static, even when they are catalyzing chemical reactions. But researchers at Instituto de Química-Física “Rocasolano” and the Sandia National Labs showed that this view is incorrect for magnetite (Fe3O4), an important industrial catalyst. Real-time microscopy reveals that magnetite’s surface steps advance continuously during oxygen exposure. The iron needed for this growth of new magnetite comes from the material’s interior. The first step of oxidation, dissociative oxygen adsorption, occurs uniformly over magnetite’s terraces. The common assumption in heterogeneous catalysis, in contrast, is that redox reactions occur at surface steps. Furthermore, this research establishes that catalytic redox cycles on magnetite do not involve creating and destroying oxygen vacancies, as usually assumed. Instead, catalytic cycles grow and etch the crystal through a different defect, iron vacancies.

1(a-d) Low-energy electron microscopy images from Fe3O4(100) exposed to O2. Surface steps are at the boundaries between the bright/dark bands. The red lines show one step advancing. Field of view = 20 m. (e) Spiral step topography. (f) Model of Fe3O4 growth at the surface. e un escalón. Campo de visión = 20 µm. (e) Topografía de escalón espiral. (f) Modelo de crecimiento de Fe3O4 (100) en la superficie.









Shu Nie,1 Elena Starodub,1 Matteo Monti,2 David Siegel,1 Lucía Vergara,2 Farid El Gabaly,1 Norman Bartelt,1 Juan de la Figuera,2 and Kevin McCarty1, Insight into magnetite’s redox catalysis from observing surface morphology during oxidation, J. Am. Chem. Soc., in press (2013). 1 = SNL, 2 = IQFR


Las galectinas: tan parecidas, tan diferentes

Thursday June 27th 2013

12:00 Salón de Actos

"Actividades de investigación en el Grupo de Química Atmosférica y Clima"

Thursday 20th June 2013

12:00 Salón de Actos de IQFR

"Estudios mediante RMN de la estructura y estabilidad de ácidos nucleicos con furanosas modificada"

Tuesday 18th June  2013

12:00 Salón de Actos del IQRF

"From Bayes (to electrons to proteins) to therapies"

Wednesday 19th, 2013

12:00 Salón de Actos