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Disulfide bond formation in vivo is linked to many essential intracellular processes; protein regulation and signaling, chemical transformations, and oxidative protein folding. Oxidative protein folding is an enzyme catalyzed process which is controlled by dedicated protein thiol oxidoreductases. In this work the oxidative protein folding within the mammalian endoplasmic reticulum (ER) is examined from an enzymological perspective. Evidence for the rapid reduction of PDI by reduced glutathione is presented in the context of PDI-first pathways. Next, strategies and challenges for the determination of the concentrations of reduced and oxidized glutathione and of the ratios of PDIred:PDIox is discussed. After a discussion of the use of natively encoded fluorescent probes to report the glutathione redox poise of the ER, a complementary strategy to discontinuously survey the redox state of as many redox-active disulfides as can be identified by ratiometric LC–MS–MS methods in order to better understand redox linked species. Next, we investigate the specificity of the human Mia40/lfALR system towards non-cognate unfolded protein substrates to assess whether the efficient introduction of disulfides requires a particular amino acid sequence context or the presence of an IMS targeting signal. Mia40 is found to be effective oxidant of non-cognate substrates, but is an ineffective protein disulfide isomerase when its ability to restore enzymatic activity from scrambled RNase is compared to that of protein disulfide isomerase. Mia40’s ability to bind amphipathic peptides tested by the insulin reductase assay. The consequences of these studies, mitochondrial oxidative protein folding, and the transit of polypeptides is discussed. Finally, the development of disulfide linked genetically encoded fluorescent probes for analyte-specific imaging are demonstrated. Current classes of intracellular probes depend on the selection of binding domains that either undergo conformational changes on analyte binding or can be linked to thiol redox chemistry. Here, novel probes were designed by fusing a flavoenzyme, whose fluorescence is quenched on reduction by the analyte of interest, with a GFP domain to allow for rapid and specific ratiometric sensing. Two flavoproteins, Escherichia coli thioredoxin reductase and Saccharomyces cerevisiae lipoamide hydrogenase, were successfully developed into thioredoxin and NAD+/NADH specific probes respectively and their performance was evaluated in vitro and in vivo. These genetically encoded fluorescent constructs represent a modular approach to intracellular probe design that should extend the range of metabolites that can be quantitated in living cells.
Hydrogen peroxide (H2O2) is a well-known oxidant species commonly produced in eukaryotic organisms as a result of cellular metabolism that plays a central role in numerous processes in cells, and dysregulation of this species can result in a number of different disease states in human cells. In the case of cancer, elevated metabolism is believed to result in higher rates of H2O2 production in these cells, as well as more susceptibility to H2O2-induced apoptosis than normal cells. To this end, researchers have identified several therapeutic compounds that are believed to kill cancer cells via the intracellular elevation of one or more oxidants. However, due to the limitations of current tools for detection of these species, little is known about which therapeutic compounds induce toxicity via elevation of specific oxidants, which would aid in the identification of susceptible tumors to these treatments. Currently, the main limitation of genetically-encoded tools for detection of H2O2 in these applications is the low sensitivity to H2O2 . Most genetically-encoded probes for this species used in human cells utilize H2O2-responsive domains with reaction rate coefficients nearly two orders of magnitude lower than other, more reactive peroxidases in the cell, such as peroxiredoxins (Prxs). In this regard, several studies have demonstrated that Prxs should react with the majority of intracellular H2O2 on the basis of a high reaction rate coefficient with H2O2 and intracellular abundance. In light of these studies, research in the field of redox biology has shifted to focus more on Prxs' role as natural sensors of H2O2 fluctuations in human cells. To this end, the first part of my thesis project focuses on the development of a genetically-encoded probe for H2O2-mediated human Prx2 oxidation in human cells. The second part of my thesis focuses on the application of this probe in a high-throughput screen to identify small-molecule cancer therapeutics that act through H2O2-mediated mechanisms. Together, this thesis lays the foundation for a new class of genetically-encoded sensors that enable specific, sensitive measurement of H2O2 perturbations in human cells in response to redox-based therapeutics, which will facilitate the advancement of these therapeutic compounds in the future.
The formation of disulphide bonds is probably the most influential modification of proteins. These bonds are unique among post-translational modifications of proteins as they can covalently link cysteine residues far apart in the primary sequence of a protein. This has the potential to convey stability to otherwise marginally stable structures of proteins. However, the reactivity of cysteines comes at a price: the potential to form incorrect disulphide bonds, interfere with folding, or even cause aggregation. An elaborate set of cellular machinery exists to catalyze and guide this process: facilitating bond formation, inhibiting unwanted pairings and scrutinizing the outcomes. Only in recent years has it become clear how intimately connected this cellular machinery is with protein folding helpers, organellar redox balance and cellular homeostasis as a whole. This book comprehensively covers the basic principles of disulphide bond formation in proteins and describes the enzymes involved in the correct oxidative folding of cysteine-containing proteins. The biotechnological and pharmaceutical relevance of proteins, their variants and synthetic replicates is continuously increasing. Consequently this book is an invaluable resource for protein chemists involved in realted research and production.
Although nitric oxide (NO) is an important biological signaling molecule, its free-radical electronic configuration makes it a most reactive molecule and the scariest colorless gas causing immense environmental and health hazards. Detection of NO levels in biological samples and in the atmosphere is therefore crucial. In the past few years, extensive efforts have been devoted to developing many active sensors and effective devices for detecting and quantifying atmospheric NO, NO generated in biological samples, and NO exhaled in the human breath. This book provides a concrete summary of recent state-of-the-art small-molecule probes and novel carbon nanomaterials used for chemical, photoluminescent, and electrochemical NO detection. One chapter is especially dedicated to the available devices used for detecting NO in the human breath that indirectly infers to lung inflammation. The authors with expertise in diverse dimensions have attempted to cover almost all areas of NO sensing.
In Fluorescent Protein-Based Biosensors: Methods and Protocols, experts in the field have assembled a series of protocols describing several methods in which fluorescent protein-based reporters can be used to gain unique insights into the regulation of cellular signal transduction. Genetically encodable fluorescent biosensors have allowed researchers to observe biochemical processes within the endogenous cellular environment with unprecedented spatiotemporal resolution. As the number and diversity of available biosensors grows, it is increasingly important to equip researchers with an understanding of the key concepts underlying the design and application of genetically encodable fluorescent biosensors to live cell imaging. Written in the successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible protocols, and notes on troubleshooting and avoiding known pitfalls. Authoritative and easily accessible, Fluorescent Protein-Based Biosensors: Methods and Protocols promises to be a valuable resource for researchers interested in applying current biosensors to the study of biochemical processes in living cells as well as those interested in developing novel biosensors to visualize other cellular phenomena.
This book review series presents current trends in modern biotechnology. The aim is to cover all aspects of this interdisciplinary technology where knowledge, methods and expertise are required from chemistry, biochemistry, microbiology, genetics, chemical engineering and computer science. Volumes are organized topically and provide a comprehensive discussion of developments in the respective field over the past 3-5 years. The series also discusses new discoveries and applications. Special volumes are dedicated to selected topics which focus on new biotechnological products and new processes for their synthesis and purification. In general, special volumes are edited by well-known guest editors. The series editor and publisher will however always be pleased to receive suggestions and supplementary information. Manuscripts are accepted in English. /div
This volume compiles a broad range of step-by-step protocols, complementary to the ones published in the first edition of this book, to study various aspects of mitochondrial structure and function in different model organisms, both in vitro and in vivo. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Authoritative and practical, Mitochondria: Practical Protocols, Second Edition aims to be useful for beginners as well as for experienced researchers in the field.
Over the last three decades a lot of research on the role of metals in biochemistry and medicine has been done. As a result many structures of biomolecules with metals have been characterized and medicinal chemistry studied the effects of metal containing drugs. This new book (from the EIBC Book Series) covers recent advances made by top researchers in the field of metals in cells [the “metallome”] and include: regulated metal ion uptake and trafficking, sensing of metals within cells and across tissues, and identification of the vast cellular factors designed to orchestrate assembly of metal cofactor sites while minimizing toxic side reactions of metals. In addition, it features aspects of metals in disease, including the role of metals in neuro-degeneration, liver disease, and inflammation, as a way to highlight the detrimental effects of mishandling of metal trafficking and response to "foreign" metals. With the breadth of our recently acquired understanding of metals in cells, a book that features key aspects of cellular handling of inorganic elements is both timely and important. At this point in our understanding, it is worthwhile to step back and take an expansive view of how far our understanding has come, while also highlighting how much we still do not know. The content from this book will publish online, as part of EIBC in December 2013, find out more about the Encyclopedia of Inorganic and Bioinorganic Chemistry, the essential online resource for researchers and students working in all areas of inorganic and bioinorganic chemistry.
The purpose of this volume is to provide a synopsis of present knowledge of the structure, organisation, and function of cellular organelles with an emphasis on the examination of important but unsolved problems, and the directions in which molecular and cell biology are moving. Though designed primarily to meet the needs of the first-year medical student, particularly in schools where the traditional curriculum has been partly or wholly replaced by a multi-disciplinary core curriculum, the mass of information made available here should prove useful to students of biochemistry, physiology, biology, bioengineering, dentistry, and nursing. It is not yet possible to give a complete account of the relations between the organelles of two compartments and of the mechanisms by which some degree of order is maintained in the cell as a whole. However, a new breed of scientists, known as molecular cell biologists, have already contributed in some measure to our understanding of several biological phenomena notably interorganelle communication. Take, for example, intracellular membrane transport: it can now be expressed in terms of the sorting, targeting, and transport of protein from the endoplasmic reticulum to another compartment. This volume contains the first ten chapters on the subject of organelles. The remaining four are in Volume 3, to which sections on organelle disorders and the extracellular matrix have been added.