A counter-enzyme complex regulates glutamate metabolism in Bacillus subtilis.

Multi-enzyme assemblies composed of metabolic enzymes catalyzing sequential reactions are being increasingly studied. Here, we report the discovery of a 1.6 megadalton multi-enzyme complex from Bacillus subtilis composed of two enzymes catalyzing opposite ('counter-enzymes') rather than sequential reactions: glutamate synthase (GltAB) and glutamate dehydrogenase (GudB), which make and break glutamate, respectively.

Direct-MS analysis of antibody-antigen complexes.

In recent decades, antibodies (Abs) have attracted the attention of academia and the biopharmaceutical industry due to their therapeutic properties and versatility in binding a vast spectrum of antigens. Different engineering strategies have been developed for optimizing Ab specificity, efficacy, affinity, stability and production, enabling systematic screening and analysis procedures for selecting lead candidates. This quality assessment is critical but usually demands time-consuming and labor-intensive purification procedures.

Mass Spectrometry Analysis of Intact Proteins from Crude Samples.

Analysis of intact proteins by native mass spectrometry has emerged as a powerful tool for obtaining insight into subunit diversity, post-translational modifications, stoichiometry, structural arrangement, stability, and overall architecture. Typically, such an analysis is performed following protein purification procedures, which are time consuming, costly, and labor intensive. As this technology continues to move forward, advances in sample handling and instrumentation have enabled the investigation of intact proteins and in crude samples, offering rapid analysis and improved conservation of the biological context.

Comparative Structural Analysis of 20S Proteasome Ortholog Protein Complexes by Native Mass Spectrometry.

Ortholog protein complexes are responsible for equivalent functions in different organisms. However, during evolution, each organism adapts to meet its physiological needs and the environmental challenges imposed by its niche. This selection pressure leads to structural diversity in protein complexes, which are often difficult to specify, especially in the absence of high-resolution structures.

Direct characterization of overproduced proteins by native mass spectrometry.

Proteins derived by recombinant technologies must be characterized to ensure quality, consistency and optimal production. These properties are usually assayed following purification procedures that are time consuming and labor intensive. Here, we describe a native mass spectrometry (MS) approach, direct-MS, for rapid characterization of intact overexpressed proteins immediately from crude samples.

Structural mass spectrometry approaches to study the 20S proteasome.

The 20S proteasome is a large multisubunit proteolytic machine that is central to intracellular protein degradation. It is found in all three kingdoms of life and is ubiquitous in archaea and eukaryotes. Since its discovery, much effort employing a diverse array of structural biology methods has been applied to help understand its structure/function relationships.

Rapid characterization of secreted recombinant proteins by native mass spectrometry.

Characterization of overexpressed proteins is essential for assessing their quality, and providing input for iterative redesign and optimization. This process is typically carried out following purification procedures that require pronounced cost of time and labor. Therefore, quality assessment of recombinant proteins with no prior purification offers a major advantage.