Purification and Characterization of Lymphokines: An Approach to the Study of Molecular Mechanisms of Cell-Mediated Immunity (Part 2 of 3)

Author(s):  
Maurice K. Gately ◽  
Manfred M. Mayer
Science ◽  
2021 ◽  
Vol 373 (6553) ◽  
pp. eabf8761
Author(s):  
C. J. Markin ◽  
D. A. Mokhtari ◽  
F. Sunden ◽  
M. J. Appel ◽  
E. Akiva ◽  
...  

Systematic and extensive investigation of enzymes is needed to understand their extraordinary efficiency and meet current challenges in medicine and engineering. We present HT-MEK (High-Throughput Microfluidic Enzyme Kinetics), a microfluidic platform for high-throughput expression, purification, and characterization of more than 1500 enzyme variants per experiment. For 1036 mutants of the alkaline phosphatase PafA (phosphate-irrepressible alkaline phosphatase of Flavobacterium), we performed more than 670,000 reactions and determined more than 5000 kinetic and physical constants for multiple substrates and inhibitors. We uncovered extensive kinetic partitioning to a misfolded state and isolated catalytic effects, revealing spatially contiguous regions of residues linked to particular aspects of function. Regions included active-site proximal residues but extended to the enzyme surface, providing a map of underlying architecture not possible to derive from existing approaches. HT-MEK has applications that range from understanding molecular mechanisms to medicine, engineering, and design.


2020 ◽  
Vol 295 (16) ◽  
pp. 5292-5306 ◽  
Author(s):  
Xiaoying Li ◽  
Lijie Zhang ◽  
Yanjie Liu ◽  
Lizhen Ma ◽  
Nianzhi Zhang ◽  
...  

Lethal infections by strains of the highly-pathogenic avian influenza virus (HPAIV) H5N1 pose serious threats to both the poultry industry and public health worldwide. A lack of confirmed HPAIV epitopes recognized by cytotoxic T lymphocytes (CTLs) has hindered the utilization of CD8+ T-cell–mediated immunity and has precluded the development of effectively diversified epitope-based vaccination approaches. In particular, an HPAIV H5N1 CTL-recognized epitope based on the peptide MHC-I–β2m (pMHC-I) complex has not yet been designed. Here, screening a collection of selected peptides of several HPAIV strains against a specific pathogen-free pMHC-I (pBF2*1501), we identified a highly-conserved HPAIV H5N1 CTL epitope, named HPAIV–PA123–130. We determined the structure of the BF2*1501–PA123–130 complex at 2.1 Å resolution to elucidate the molecular mechanisms of a preferential presentation of the highly-conserved PA123–130 epitope in the chicken B15 lineage. Conformational characteristics of the PA123–130 epitope with a protruding Tyr-7 residue indicated that this epitope has great potential to be recognized by specific TCRs. Moreover, significantly increased numbers of CD8+ T cells specific for the HPAIV–PA123–130 epitope in peptide-immunized chickens indicated that a repertoire of CD8+ T cells can specifically respond to this epitope. We anticipate that the identification and structural characterization of the PA123–130 epitope reported here could enable further studies of CTL immunity against HPAIV H5N1. Such studies may aid in the development of vaccine development strategies using well-conserved internal viral antigens in chickens.


2016 ◽  
Vol 60 ◽  
pp. 33-40 ◽  
Author(s):  
Yuta Matsuura ◽  
Takeshi Yabu ◽  
Hajime Shiba ◽  
Tadaaki Moritomo ◽  
Teruyuki Nakanishi

2020 ◽  
Author(s):  
C.J. Markin ◽  
D.A. Mokhtari ◽  
F. Sunden ◽  
M.J. Appel ◽  
E. Akiva ◽  
...  

AbstractSystematic and extensive investigation of enzymes is needed to understand their extraordinary efficiency and meet current challenges in medicine and engineering. We present HT-MEK, a microfluidic platform for high-throughput expression, purification, and characterization of >1500 enzyme variants per experiment. For 1036 mutants of the alkaline phosphatase PafA, we performed >670,000 reactions to determine >5000 kinetic and physical constants for multiple substrates and inhibitors. These constants allowed us to uncover extensive kinetic partitioning to a misfolded state and isolate catalytic effects, revealing spatially contiguous “regions” of residues linked to particular aspects of function. These regions included active-site proximal residues but also extended to the enzyme surface, providing a map of underlying architecture that could not be derived from existing approaches. HT-MEK, using direct and coupled fluorescent assays, has future applications to a wide variety of problems ranging from understanding molecular mechanisms to medicine to engineering and design.One Sentence SummaryHT-MEK, a microfluidic platform for high-throughput, quantitative biochemistry, reveals enzyme architectures shaping function.


2016 ◽  
Vol 53 ◽  
pp. 73
Author(s):  
Yuta Matsuura ◽  
Takeshi Yabu ◽  
Hajime Shiba ◽  
Teruyuki Nakanishi

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 135 ◽  
Author(s):  
Wei Jiang ◽  
Henriette Macmillan ◽  
Anne-Marie Madec ◽  
Elizabeth D. Mellins

Autoantibodies against antigens expressed by insulin-producing β cells are circulating in both healthy individuals and patients at risk of developing Type 1 diabetes. Recent studies suggest that another set of antibodies (anti-idiotypic antibodies) exists in this antibody/antigen interacting network to regulate auto-reactive responses. Anti-idiotypic antibodies may block the antigen-binding site of autoantibodies or inhibit autoantibody expression and secretion. The equilibrium between autoantibodies and anti-idiotypic antibodies plays a critical role in mediating or preventing autoimmunity. Herein, using GAD65/anti-GAD65 autoantibodies as a model system, we aimed at establishing reliable approaches for purification of highly pure autoantibodies for the downstream investigation of molecular mechanisms underlying such a network.


2001 ◽  
Vol 79 (4) ◽  
pp. 499-506 ◽  
Author(s):  
James I Rearick ◽  
Eric S Calhoun

Previous work has demonstrated that the activity of the enzyme cholesterol sulfotransferase is rapidly and dramatically increased upon squamous differentiation of a variety of epithelial cells in culture, including epidermal keratinocytes. As a step toward understanding the molecular mechanisms underlying this differentiation-related change, we now report the partial purification and characterization of this enzyme activity from rat skin. Supernatant solutions from rat skin homogenates were subjected to a series of column chromatography steps including anion exchange, gel filtration, chromatofocusing and hydrophobic interaction chromatography. The purification procedure resulted in cholesterol sulfotransferase activity purified 2700-fold with a 11% recovery. The most purified preparation yielded a major Coomassie blue-stained band on denaturing polyacrylamide gel electrophoresis of an apparent molecular weight (MW) of 40 000 Da. Photoaffinity labeling with the donor substrate, 3'-phosphoadenosine-5'-phospho-[35S]-sulfate resulted in a single radiolabeled protein band on denaturing polyacrylamide gel electrophoresis, again of apparent MW 40 000 Da, strongly suggesting that the major Coomassie blue-stained band in the most purified preparation is the cholesterol sulfotransferase protein. Among 3β-hydroxysteroids with a Δ5 double bond that were tested, each served as a substrate, while androgens, estrogens, corticosteroids, p-nitrophenol and DOPA did not serve as substrates. Apparent Michaelis constants for the 3β-hydroxysteroid substrates ranged from 0.6 to 8 µM.Key words: sulfotransferase, ichthyosis, cholesterol, skin, enzymology.


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