In JoVE (2)
Articles by Noam Kirshenbaum in JoVE
Analyzing Large Protein Complexes by Structural Mass Spectrometry Noam Kirshenbaum1, Izhak Michaelevski1, Michal Sharon1 1Department of Biological Chemistry, Weizmann Institute of Science Mass spectrometry has proven to be a valuable tool for analyzing large protein complexes. This method enables insights into the composition, stoichiometry and overall architecture of multi-subunit assemblies. Here, we describe, step-by-step, how to perform a structural mass spectrometry analysis, and characterize macromolecular structures.
T-wave Ion Mobility-mass Spectrometry: Basic Experimental Procedures for Protein Complex Analysis Izhak Michaelevski1, Noam Kirshenbaum1, Michal Sharon1 1Department of Biological Chemistry, Weizmann Institute of Science Ion mobility-mass spectrometry is an emerging gas-phase technology that separates ions, based on their collision cross-section and mass. The method provides three-dimensional information on the overall topology and shape of protein complexes. Here, we outline a basic procedure for instrument setting and optimization, calibration of drift times, and data interpretation.
Other articles by Noam Kirshenbaum on PubMed
Peculiar Mechanistic and Structural Features of the Carboplatin-cytochrome C System Revealed by ESI-MS Analysis Journal of Biological Inorganic Chemistry : JBIC : a Publication of the Society of Biological Inorganic Chemistry. Jun, 2008 | Pubmed ID: 18350322 Carboplatin (CPT), today the most important platinum(II) anticancer drug, manifests an extreme kinetic inertness, in vitro, at physiological pH; the actual mechanisms for its activation inside cells are still poorly understood. We show here that horse heart cytochrome c reacts with CPT, leading to the formation of stable platinum/protein adducts. The two major CPT-cytochrome c species resulting from the aforementioned reaction were characterised by electrospray ionisation mass spectrometry (ESI-MS). Notably, both these adducts have the ability to react with guanosine 5'-monophosphate (5'-GMP), giving rise to the respective cytochrome c-CPT-5'-GMP ternary complexes. Additional ESI-MS measurements on enzymatically cleaved cytochrome c adducts suggest that protein platination probably occurs at Met65. The mechanistic implications of these findings are discussed.
Metamorphic Proteins Mediate Evolutionary Transitions of Structure Proceedings of the National Academy of Sciences of the United States of America. Apr, 2010 | Pubmed ID: 20368465 The primary sequence of proteins usually dictates a single tertiary and quaternary structure. However, certain proteins undergo reversible backbone rearrangements. Such metamorphic proteins provide a means of facilitating the evolution of new folds and architectures. However, because natural folds emerged at the early stages of evolution, the potential role of metamorphic intermediates in mediating evolutionary transitions of structure remains largely unexplored. We evolved a set of new proteins based on approximately 100 amino acid fragments derived from tachylectin-2--a monomeric, 236 amino acids, five-bladed beta-propeller. Their structures reveal a unique pentameric assembly and novel beta-propeller structures. Although identical in sequence, the oligomeric subunits adopt two, or even three, different structures that together enable the pentameric assembly of two propellers connected via a small linker. Most of the subunits adopt a wild-type-like structure within individual five-bladed propellers. However, the bridging subunits exhibit domain swaps and asymmetric strand exchanges that allow them to complete the two propellers and connect them. Thus, the modular and metamorphic nature of these subunits enabled dramatic changes in tertiary and quaternary structure, while maintaining the lectin function. These oligomers therefore comprise putative intermediates via which beta-propellers can evolve from smaller elements. Our data also suggest that the ability of one sequence to equilibrate between different structures can be evolutionary optimized, thus facilitating the emergence of new structures.