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Biomedical subjects

E Thulin

Publications and source records attributed to E Thulin.

70 records · Page 4Linked to original sources
PubMed1982

NMR studies on parvalbumin phylogeny and ionic interactions.

The inspection of several muscular parvalbumins from different species by two NMR methods (113Cd resonance and 1H relaxation measurements) allows two classes of parvalbumins to be distinguished according to their ion-binding properties. This result is in agreement with the phylogenetic classification of parvalbumins in two series, alpha and beta, which was established on the basis of the primary structures of these proteins. All parvalbumins are characterized by the presence of two primary cationic sites CD and EF, with structural features closely related to those already known on the basis of X-ray crystallographic studies of the beta parvalbumin pI 4.25 from carp muscle. However, parvalbumins of the beta series are characterized by a secondary cation (Ca2+, Mg2+ and other cations) binding site which is absent (or at least inaccessible) in parvalbumins of the alpha series. The major component from thornback ray (pI 4.45) behaves as an alpha parvalbumin as shown by the present NMR studies, although its primary structure suggests a closer similarity with the parvalbumins of the beta series.

Animals↗
PubMed1982

Observation of the 43Ca NMR signals from Ca2+ ions bound to calmodulin, parvalbumin, and troponin C.

Through the combined use of isotopically enriched 43Ca2+, high magnetic field, Fourier transform techniques, and a high-performance probe, the 43Ca NMR signals from ions bound to three proteins have been observed. These proteins are calmodulin, parvalbumin, and troponin C. Both longitudinal (1/T1) and transverse (1/T2) relaxation rates were measured for protein-bound 43Ca2+, and the quadrupole coupling constant and correlation time were obtained from these data. The calculated correlation times are in good agreement with the rotational correlation time for the entire protein molecules, which indicates that the Ca2+-binding sites are relatively rigid.

Animals↗
PubMed1979

Ion binding to cytochrome c studied by nuclear magnetic quadrupole relaxation.

The enhancement of the 35Cl- transverse relaxation rate on binding of chloride ions to oxidized and reduced cytochrome c has been studied under conditions of variable sodium chloride concentration, temperature, pH, sodium phosphate, iron hexacyanide, and sodium cyanide concentration. The results revealed the presence of a strong binding site(s) for chloride in both oxidized and reduced cyt c, with a higher affinity in ferrocytochrome c. Competition experiments suggest that these sites also bind iron hexacyanide and phosphate. Cyanide binding to the iron in ferricytochrome c at alkaline and neutral pH was shown to decrease the binding of chloride. The pH dependence of the 35Cl- relaxation rate has been fitted by using literature pK values for ionizable groups. No indications of Na+ binding to oxidized and reduced cytochrome c have been observed by using 23Na+ NMR. Our results suggest that chloride is bound near the exposed heme edge and that the surface structure or dynamics in this region are different in the two oxidation states.

Chlorides↗
PubMed1977

Purification of prealbumin from human and canine serum using a two-step affinity chromatographic procedure.

1. A two-step-method is described by which human and canine prealbumin have been isolated from serum in good yield and high purity. The first step involves binding and release of prealbumin by a thiol-disulfide interchange reaction with thiol-Sepharose 4B. The second step consists of reversible binding of prealbumin to retinol-binding protein covalently linked to Sepharose 4B. 2. The canine prealbumin was immunochemically identified as an alpha2-globulin. Like human prealbumin it is a tetramer with some 10% smaller subunits than human prealbumin. Both proteins are devoid of carbohydrate and both bind thyroxin.

Animals↗
PubMed1975

Purification of alpha1-antitrypsin from plasma through thiol-disulfide interchange.

1. Monomeric nu-chains were conjugated with CNBr-activated Sepharose 4B. The C-terminal cysteine of the conjugated nu-chain was converted to a mixed disulfide with 3-carboxy-4-nitro-benzenethiol (Nbs) and used to separate plasma proteins with reactive thiol groups. The plasma proteins, alpha1-antitrypsin and prealbumin have the greatest affinity for the interchange reaction with mixed disulfides. The disulfide link between alpha1-antitrypsin and nu-chain is sensitive to excess Nbs, and is selectively cleaved in the presence of 5,5'-dithiobis(2-nitrobenzoate) (Nbs2) which accepts the sulfhydryl group of alpha1-antitrypsin. 2. A Simple method developed for the isolation of human alpha1-antitrypsin was equally effective for the various inherited phenotypes and for alpha1-antitrypsin from the dog, baboon, and monkey, Glutathione-Sepharose was also used successfully, but the nu-chain conjugate yielded alpha1-antitrypsin less contaminated with mercaptalbumin and prealbumin. 3. The alpha1-antitrypsin is harvested from this procedure as a mixed disulfide with Nbs. The negative charge of Nbs at pH 8.1 causes an increased electrophoretic mobility of the alpha1-antitrypsin derivative. Mild reduction liberates Nbs and electrophoretic mobility of alpha1-antitrypsin returns to normal. The method described can increase the alpha1-antitrypsin content of a plasma fraction from 5% of the total protein to 95% within one day with a yield of about 50%. This purification procedure does not exert any detectable effect on microheterogeneity.

Animals↗
PubMed1975

Thiol-disulfide interchange in the binding of bence jones proteins to alpha-antitrypsin, prealbumin, and albumin.

Native light Ig chains of kappa- but not of lambda-type form -S-S linked complexes with prealbumin, alpha1-AT and albumin in vivo. kappa-chains isolated from urines have cysteinyls which are more promptly reacting with dithionitrobenzoate (DTNB) than lambda-chains. Both are monomerized on this reaction. On addition to plasma mixed disulfides between both types of light chains and DTNB form larger amounts of complexes than the native chains. The lower reactivity of native lambda-chains to the plasma proteins can be explained by their higher dimer stability. From the light chain reactions obtained with isolated alpha1-AT and albumin it is concluded that alpha1-AT has a disulfide which efficiently interchanges with monomeric, light chain thiolate ions released from thionitrobenzoate derivates of light chains and that on interchange with the derivatized light chains albumin releases more free light chains into the solution than are bound to albumin. Addition of derivatized light chains to a mixture of alpha1-AT and albumin increases the yield of alpha1-AT complexes and decreases the amount of albumin complexes formed. The relative amount of the different complexes formed in the latter experiments corresponds to the findings in vivo in patients with Bence Jones proteinemia. Prealbumin and alpha1-AT in plasma have a roughly 10-fold stronger tendency to link the light chains than albumin. The complexes are formed through thiol-disulfide interchange though neither the disulfide of native alpha1-AT nor the thiols of prealbumin is available for reaction with DTNB. The three plasma proteins may together constitute a system for linkage and transport of peptides with reactive thiols or disulfides released into the extracellular fluids. The trypsin and elastase binding and inhibiting capacity of alpha1-AT remains after cleavage of the internal -S-S-bridge of alpha1-AT through interchange with a light chain thiol for which reason an intact internal -S-S-bridge of alpha1-AT is not necessary for inhibition and linkdage of the enzymes.

Bence Jones Protein↗