High resolution 'H nuclear magnetic resonance spectroscopy and optical stopped-flow techniques have been used to study the metal binding properties of a site-specific mutant of bacterial recombinant oncomodulin in which glutamate has replaced a liganding aspartate at position 59 in the CD calcium-binding site.In particular we have followed the replacement of calcium by lutetium in bacterial recombinant oncomodulin and D59E oncomodulin to provide a measure of the protein's preferences for metal ions of different ionic radii.The result of the Asp + Glu substitution is to make the mutant oncomodulin more similar to rat parvalbumin in terms of its relative CD-and EF-domain affinities for lutetium(III), that is to increase its affinity for metal ions with smaller ionic radii.This finding supports the original hypothesis that the presence of Asp at sequence position 59 is an important factor in the reduced preference of the CD site of oncomodulin for smaller metals such as magnesium (Williams, T.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFluorine-19 nuclear magnetic resonance studies of lipid fatty acyl chain order and dynamics in Acholeplasma laidlawii B membranes. Orientational order in the presence of positional isomers of trans-octadecenoic acidPeter M. Macdonald, Brian D. Sykes, and Ronald N. McElhaneyCite this: Biochemistry 1985, 24, 9, 2237–2245Publication Date (Print):April 1, 1985Publication History Published online1 May 2002Published inissue 1 April 1985https://pubs.acs.org/doi/10.1021/bi00330a018https://doi.org/10.1021/bi00330a018research-articleACS PublicationsRequest reuse permissionsArticle Views24Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhosphorus-31 nuclear magnetic resonance studies of adenosine 5'-triphosphate bound to a nitrated derivative of G-actinManfred Brauer and Brian D. SykesCite this: Biochemistry 1981, 20, 24, 6767–6775Publication Date (Print):November 1, 1981Publication History Published online1 May 2002Published inissue 1 November 1981https://pubs.acs.org/doi/10.1021/bi00527a005https://doi.org/10.1021/bi00527a005research-articleACS PublicationsRequest reuse permissionsArticle Views56Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Antifreeze proteins (AFPs) designate a class of proteins that are able to bind to and inhibit the growth of macromolecular ice. These proteins have been characterized from a variety of organisms. Recently, the structures of AFPs from the spruce budworm ( Choristoneura fumiferana ) and the yellow mealworm ( Tenebrio molitor ) have been determined by NMR and X‐ray crystallography. Despite nonhomologous sequences, both proteins were shown to consist of β‐helices. We review the structures and dynamics data of these two insect AFPs to bring insight into the structure–function relationship and explore their β‐helical architecture. For the spruce budworm protein, the fold is a left‐handed β‐helix with 15 residues per coil. The Tenebrio molitor protein consists of a right‐handed β‐helix with 12 residues per coil. Mutagenesis and structural studies show that the insect AFPs present a highly rigid array of threonine residues and bound water molecules that can effectively mimic the ice lattice. Comparisons of the newly determined ryegrass and carrot AFP sequences have led to models suggesting that they might also consist of β‐helices, and indicate that the β‐helix might be used as an AFP structural motif in nonfish organisms.
The calmodulin antagonist W7 binds to troponin C in the presence of Ca(2+) and inhibits striated muscle contraction. This study integrates multiple data into the structure of the regulatory domain of human cardiac troponin C (cNTnC) bound to Ca(2+) and W7. The protein-W7 interface is defined through a three-dimensional {(1)H,(13)C}-edited-{(1)H,(12)C}-detected NOESY NMR experiment, and other aspects of the structure are modeled as perturbations to previously known coordinates and restraints. The structure determination protocol optimizes the protein-W7 contacts prior to the introduction of protein-W7 steric interactions or conformational changes in the protein. The structure determination protocol gives families of conformers that all have an optimal docking as assessed by satisfaction of the target function. The structure supports the previously proposed troponin I blocking mechanism for the activity of W7 in striated muscle and suggests a role for the flexible tail of W7 in stabilization of the bound state. This clarifies the structure-activity relationships of W7 and implicates an electrostatically mediated component of activity in common analogues of W7, including the antipsychotic trifluoroperazine and the cardiotonic levosimendan.
Structural analysis of chemokines has revealed that the alpha/beta structural-fold is highly conserved among both the CXC and CC chemokine classes. Although dimerization and aggregation is often observed, the chemokines function as monomers. The critical receptor binding regions are in the NH2-terminal 20 residues of the protein and are the least ordered in solution. The flexible NH2-terminal region is the most critical receptor binding site and a second site also exists in the loop that follows the two disulfides. The well-ordered regions are not directly involved in receptor binding but, along with the disulfides, they provide a scaffold that determines the conformation of the sites that are critical for receptor binding. These general requirements for function are common to all the chemokines. For the CC chemokines, receptor activation and receptor binding regions are separate within the 10 residue NH2-terminal region. This has allowed identification of high affinity analogs that do not activate the receptor and are potent antagonists.
