Paramagnetic relaxation enhancement of membrane proteins by incorporation of the metal-chelating unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl)propanoic acid (HQA)
Paramagnetic relaxation enhancement of membrane proteins by incorporation of the metal-chelating unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl)propanoic acid (HQA)
The use of paramagnetic constraints in protein NMR is an active area of research because of the benefits of long-range distance measurements (>10Â*Ã?). One of the main issues in successful execution is the incorporation of a paramagnetic metal ion into diamagnetic proteins. The most common metal ion tags are relatively long aliphatic chains attached to the side chain of a selected cysteine residue with a chelating group at the end where it can undergo substantial internal motions, decreasing the accuracy of the method. An attractive alternative approach is to incorporate an unnatural amino acid that binds metal ions at a specific site on the protein using the methods of molecular biology. Here we describe the successful incorporation of the unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl)propanoic acid (HQA) into two different membrane proteins by heterologous expression in E. coli. Fluorescence and NMR experiments demonstrate complete replacement of the natural amino acid with HQA and stable metal chelation by the mutated proteins. Evidence of site-specific intra- and inter-molecular PREs by NMR in micelle solutions sets the stage for the use of HQA incorporation in solid-state NMR structure determinations of membrane proteins in phospholipid bilayers.
Movements of proteins can be predicted from their amino acid sequence - HealthCanal.com
Movements of proteins can be predicted from their amino acid sequence - HealthCanal.com
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Movements of proteins can be predicted from their amino acid sequence
HealthCanal.com
Researchers of the VIB department of Structural Biology, in a collaboration within the 'Interuniversity Institute of Bioinformatics in Brussels (IB2)', have developed a method to predict how much the backbone chain of a protein moves based on only its ...
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Authors: Hefke F, Bagaria A, Reckel S, Ullrich SJ, Dötsch V, Glaubitz C, Güntert P
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Optimization of amino acid type-specific 13C and 15N labeling for the backbone assignment of membrane proteins by solution- and solid-state NMR with the UPLABEL algorithm
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Protein structure determination using Nuclear Magnetic Resonance (NMR) requires the use of molecular dynamics programs that incorporate both NMR experimental and implicit atomic data. Atomic parameters for each amino acid type are encoded in...