We describe maleic‐acid derivatives as robust cysteine‐selective reagents for protein labelling with comparable kinetics and superior stability relative to maleimides. Diamide and amido‐ester derivatives proved to be efficient protein‐labelling species with a common mechanism in which a spontaneous cyclization occurs upon addition to cysteine. Introduction of chlorine atoms in their structures triggers ring hydrolysis or further conjugation with adjacent residues, which results in conjugates that are completely resistant to retro‐Michael reactions in the presence of biological thiols and human plasma. By controlling the microenvironment of the reactive site, we can control selectivity towards the hydrolytic pathway, forming homogeneous conjugates. The method is applicable to several scaffolds and enables conjugation of different payloads. The synthetic accessibility of these reagents and the mild conditions required for fast and complete conjugation together with the superior stability of the conjugates make this strategy an important alternative to maleimides in bioconjugation.
Post-translational modifications of histones are essential in the regulation of chromatin structure and function. Among these modifications, lysine acetylation is one of the most established. Earlier studies relied on the use of chromatin containing heterogeneous mixtures of histones acetylated at multiple sites. Differentiating the individual contribution of single acetylation events towards chromatin regulation is thus of great relevance. However, it is difficult to access homogeneous samples of histones, with a single acetylation, in sufficient quantities for such studies. By engineering histone H3 with a cysteine in proximity of the lysine of interest, we demonstrate that conjugation with maleimide-DBCO followed by a strain-promoted alkyneazide cycloaddition reaction results in the acetylation of a single lysine in a controlled, site-specific manner. The chemical precision offered by our click-to-acetylate approach will facilitate access to and the study of acetylated histones.
El trabajo presenta resultados parciales de un estudio investigación que se ha propuesto describir la composición del oficio de estudiante a partir del análisis de las características que constituyeron sus principales rasgos en la universidad de gestión privada de la República Argentina en el marco de la pandemia. En el análisis se ha ponderado el conocimiento ofrecido a partir del estudio de las trayectorias biográficas, ocupacionales y académicas de los y las estudiantes del nivel de carreras de educación de nivel de grado de la Universidad Abierta Interamericana (UAI). En este avance se analizan las variables sociodemográficas que contextualizaron el oficio de estudiar, así como también su incidencia. Entre los factores salientes en torno al desarrollo del oficio de estudiar se han destacado la incidencia del trabajo, de las relaciones sociales, la organización de los espacios y los tiempos en el hogar.
Alzheimer´s Disease (AD) is one of the most common neurodegenerative disorders worldwide. Excess of β-amyloid (Aβ), a peptide with a high propensity to misfold and self-aggregate, is believed to be the major contributor to the observed neuronal degeneration and cognitive decline in AD. Here, we characterize the epitope of a novel anti-Aβ monoclonal antibody, the STAB-MAb, which has previously demonstrated picomolar affinities for both monomers (K D = 80 pM) and fibrils (K D = 130 pM) of Aβ(1–42) and has shown therapeutic efficacy in preclinical mouse models of AD. Our findings reveal a widespread epitope that embraces several key Aβ residues that have been previously described as important in the Aβ fibrillation process. Of note, STAB-MAb exhibits a stronger affinity for the N-terminus of Aβ and stabilizes an α-helix conformation in the central to N-terminal region of the peptide, in addition to disrupting a characteristic salt-bridge of a hairpin structure present in fibrils. The NMR derived epitope supports the observed results from ThT-monitored fluorescence and electron microscopy experiments, in which STAB-MAb was shown to inhibit the formation of aggregates and promote disruption of pre-formed fibrils. In combination with the published in vitro and in vivo assays, our study highlights STAB-MAb as a rare and versatile antibody with analytical, diagnostic and therapeutic efficacy.
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