OPTIMIZACIÓN DE LA EXTRACCIÓN Y PURIFICACIÓN DE UNA β-CAROTENO 15,15’-MONOOXIGENASA RECOMBINANTE A PARTIR DE CUERPOS DE INCLUSIÓN

Los forrajes utilizados en la producción de ganado bovino en el trópico tienen altos niveles de β-caroteno, que produce canales con grasa de color amarillo y demerita su valor económico. La pigmentación amarilla se debe a la actividad baja de la enzima β -caroteno 15,15’-monooxigenasa (BCMO1) en el intestino delgado e hígado. Un uso biotecnológico de esta enzima podría escindir al β -caroteno en dos moléculas de retinal, eliminar la fuente de coloración y optimizar el valor comercial de la carne del ganado bovino alimentado en pastoreo. El objetivo de este estudio fue obtener una enzima BCMO1 recombinante con actividad similar a las enzimas nativas, a partir de bacterias transformadas con el gen que codifica la b-caroteno 15,15’-monooxigenasa de Gallus gallus (gBCMO1). La enzima se obtuvo por sobre expresión a partir de una Escherichia coli XL1-Blue transformada con dicho gen, y se purificó por Cromatografía rápida de proteína líquida (Fast Protein Liquid Chromatography, FPLC); se midió la actividad in vitro del proceso por Cromatografía de afinidad por metales inmovilizados (Immobilized Metal Affinity Chromatography, IMAC) y el producto final se detectó por Cromatografía de líquidos de polaridad alta (High Polarity Liquid Chromatography, HPLC). Una proteína de aproximadamente 63 kDa se obtuvo, la cual presentó una actividad enzimática de 2993 (± 108.2) pmol mg-1 de proteína h-1 (n=3). La proteína aislada se puede evaluar como aditivo en estudios in vitro con el fin de disminuir la coloración amarilla de las canales de bovinos.

Nickel Ferrite Nanoparticles as an Adsorbent for Immobilized Metal Affinity Chromatography of Proteins

A simple method of preparing amorphous nickel ferrite nanoparticles of about 5 nm diameter is described. These particles were characterized by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The nanoparticles were evaluated for their use as a magnetic material for immobilized metal affinity chromatography (IMAC). The ferrite nanoparticles bound to bovine serum albumin (BSA) and the binding fitted Langmuir isotherm model. A high capacity of 916 mg BSA/g dried nanoparticle was observed. Six proteins (Soybean trypsin inhibitor (STI), lactate dehydrogenase (LDH), papain, catalase, β-galactosidase and casein) were used and all were found to bind at >90% level (except papain which showed 84% binding). All the proteins except LDH and β-galactosidase could be eluted with 1 M imidazole and with % activity recovery of >80%. Papain could be purified from its dried crude latex by 5-fold and purified papain showed a single band on SDS-PAGE. These nanoparticles constitute a high capacity and are magnetic material useful for IMAC and do not require any pre-functionalization.

Global quantitative analysis of the human brain proteome and phosphoproteome in Alzheimer’s disease

Alzheimer’s disease (AD) is characterized by an early, asymptomatic phase (AsymAD) in which individuals exhibit amyloid-beta (Aβ) plaque accumulation in the absence of clinically detectable cognitive decline. Here we report an unbiased multiplex quantitative proteomic and phosphoproteomic analysis using tandem mass tag (TMT) isobaric labeling of human post-mortem cortex (n = 27) across pathology-free controls, AsymAD and symptomatic AD individuals. With off-line high-pH fractionation and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) on an Orbitrap Lumos mass spectrometer, we identified 11,378 protein groups across three TMT 11-plex batches. Immobilized metal affinity chromatography (IMAC) was used to enrich for phosphopeptides from the same TMT-labeled cases and 51,736 phosphopeptides were identified. Of these, 48,992 were quantified by TMT reporter ions representing 33,652 unique phosphosites. Two reference standards in each TMT 11-plex were included to assess intra- and inter-batch variance at the protein and peptide level. This comprehensive human brain proteome and phosphoproteome dataset will serve as a valuable resource for the identification of biochemical, cellular and signaling pathways altered during AD progression.