scholarly journals The lobster carapace carotenoprotein, α-crustacyanin. A possible role for tryptophan in the bathochromic spectral shift of protein-bound astaxanthin

1991 ◽  
Vol 274 (1) ◽  
pp. 79-83 ◽  
Author(s):  
P F Zagalsky ◽  
E E Eliopoulos ◽  
J B C Findlay
Keyword(s):  
Vitamin A ◽  
Binding Sites ◽  
Untreated Control ◽  
Spectral Shift ◽  
Spectral Shifts ◽  
Tryptophan Residues ◽  
Tryptophan Modification ◽  
The Cross

Crustacyanin, cross-linked with dimethyl pimelimidate to stabilize the protein against denaturation, was used to test the effects of tryptophan modification with BNPS-skatole [3-bromo-3-methyl-2-(nitrophenylmercaptol)-3H-indole] on the ability of the apoprotein to recombine with astaxanthin. The cross-linked apoprotein re-forms alpha-crustacyanin with astaxanthin in reasonable yield following incubation of the protein under the conditions for tryptophan modification in the absence of BNPS-skatole. The BNPS-skatole-treated protein reconstitutes with astaxanthin to give a carotenoprotein with lambda max. at 472 nm, that of the carotenoid in hexane, in a yield similar to that of the BNPS-skatole-untreated control. The implied involvement of tryptophan residues at the sites of astaxanthin attachment in crustacyanin and their possible roles in the binding sites of vitamin A in vitamin A-proteins are discussed in relation to the bathochromic spectral shifts of the chromophores.

Modification of the porphyrin chromophore by ring fusion: identifying trends due to annelation of the porphyrin nucleus

2001 ◽  
Vol 05 (03) ◽  
pp. 267-288 ◽  
Author(s):  
TIMOTHY D. LASH
Keyword(s):  
Soret Band ◽  
Spectral Shift ◽  
Aromatic Rings ◽  
Ring Fusion ◽  
Spectral Shifts ◽  
Hyper Spectral ◽  
Two Factors ◽  
Porphyrin Analogues ◽  
Soret Absorption ◽  
Soret Region

The effects exerted by fused aromatic rings on the UV-vis spectra of porphyrins are surveyed. Modified porphyrin chromophores with fused benzene, 1,2-naphthalene, 9,10-phenanthrene or phenanthroline rings are surprisingly little affected even when a maximum number of ring fusions are incorporated. Linearly annealed naphtho- or anthraporphyrins show large red shifts to the Q bands but the Soret absorptions are weakened and undergo only minor bathochromic shifts. Fluoranthoporphyrins give multiple bands in the Soret region, but the Q band region is virtually unaffected by this tetracyclic ring system. On the other hand, metal chelates of fluoranthoporphyrins show surprisingly strong bands near 600 nm. Benzothiadiazole rings split and weaken the Soret band, but the Q bands region is unexceptional. However, metal coordination again produces relatively intense bands near 600 nm. The most significant results were obtained for porphyrins with fused acenaphthylene rings. Monoacenaphthoporphyrins (41) have three Soret bands at 387, 431 and 454 nm, and the longest wavelength Q band is shifted to 658 nm. opp-Diacenaphthoporphyrin (43) further shifts these bands with two Soret absorbances at 443 and 470 nm, and an additional strong peak is observed at 692 nm. The metal complexes of these systems also show strong bands between 602 and 656 nm. Still larger effects are produced by tetraacenaphthoporphyrin (47), the dication for which in trifluoroacetic acid (TFA)–chloroform has a Soret absorption at 528 nm. Tetraaryltetraacenaphthoporphyrins (48) are even more red shifted, showing Soret bands between 556 and 570 nm for the free bases and 565 to 588 nm for the related dications. The lead(II) chelate for tetraphenylporphyrin (48a) shows an additional 'hyper' spectral shift that brings the Soret band to 604 nm, and this effect can also be achieved by introducing four meso-phenylethynyl substituents onto the tetraacenaphthoporphyrin nucleus (49). In addition, by combining these two factors for the lead(II) chelate of 49, a record-breaking value for the Soret band of 642 nm can be achieved. Spectral shifts due to ring annelation in porphyrin analogues are also discussed, including those for oxybenziporphyrins, oxypyriporphyrins, carbaporphyrins and sapphyrins.

scholarly journals Vitamin A receptors. Retinoic acid binding in ocular tissues

1978 ◽  
Vol 169 (1) ◽  
pp. 87-94 ◽  
Author(s):  
B Wiggert ◽  
D R Bergsma ◽  
R Helmsen ◽  
G J Chader
Keyword(s):  
Retinoic Acid ◽  
Vitamin A ◽  
Corneal Epithelium ◽  
Binding Sites ◽  
Specific Binding ◽  
Pigment Epithelium ◽  
Sucrose Density Gradient ◽  
Ocular Tissues ◽  
Specific Binding Sites ◽  
Binding Component

Analysis of the sucrose-density-gradient patterns of the 110 000g supernatant fractions of adult and foetal retina and pigment epithelium showed them to contain a limited number of highly specific binding sites (‘receptors’) for [3H]retinoic acid that sediment at approx. 2S. Binding in pigment epithelium is higher than in any tissue yet reported. A 5S binding component is also observed and is probably due to serum contamination. Fractionation studies indicate that [3H]retinoic acid binding in the retina is lower in the photoreceptor units than in the retinal inner layers. This is in contrast with previous results that show greater [3H]retinol binding in photoreceptors. Studies with dystrophic human and rat retinas, which lack the photoreceptor layers, confirm that [3H]retinoic acid binding is greater in the non-photoreceptor layers of the retina. No specific [3H]retinoic acid binding is found in corneal epithelium, although endothelium and the conjunctiva demonstrate specific 2S binding. Such differences in retinol and retinoic acid binding may indicate different roles for the two compounds in ocular tissues.

scholarly journals Idiotypy of clonal responses to influenza virus hemagglutinin.

1981 ◽  
Vol 154 (5) ◽  
pp. 1525-1538 ◽  
Author(s):  
Y N Liu ◽  
C A Bona ◽  
J L Schulman
Keyword(s):  
Influenza Virus ◽  
Monoclonal Antibodies ◽  
Binding Sites ◽  
Cross Reactivity ◽  
Secondary Response ◽  
Antigenic Determinants ◽  
Antiviral Responses ◽  
Influenza Virus Hemagglutinin ◽  
The Cross

Anti-idiotype antisera were raised in syngeneic (BALB/c mice) and homologous (A/J mice) systems to study the cross-reactive idiotypes among monoclonal antibodies to PR8 and B/Lee virus HA and the expression of these idiotypes during primary and secondary antiviral responses of BALB/c mice. Extensive idiotypic cross-reactivity was demonstrated among monoclonal antibodies specific for distinct antigenic determinants on PR8 hemagglutinin (HA). The study of idiotypy of monoclonal antibodies against the same or overlapping antigenic determinants on B/Lee HA showed that these monoclonal antibodies may bear (a) a true individual idiotype not shared by other monoclonal antibodies, (b) idiotypes shared by few monoclonal antibodies, and (c) true cross-reactive idiotypes shared by all of these monoclonal antibodies. In contrast, no cross-reactive idiotypes were detectable among monoclonal antibodies to B/Lee HA and monoclonal antibodies to PR8 HA. Furthermore, we have shown that the anti-idiotype antibodies we used recognize determinants on monoclonal antibodies closely associated with antigenic binding sites. Finally, studies of the idiotypes expressed during primary and secondary antiviral HA responses of mice immunized with B/Lee virus revealed persistence of some idiotypes during both primary and secondary responses, whereas others were only expressed in the primary or secondary response.

scholarly journals Interpretations of cosmological spectral shifts

Open Physics ◽  
2013 ◽  
Vol 11 (3) ◽  
Author(s):  
Dag Østvang
Keyword(s):  
Hyperbolic Space ◽  
Spectral Shift ◽  
Space Time ◽  
Flat Connection ◽  
Closed Space ◽  
Spectral Shifts

AbstractIt is shown that for Robertson-Walker models with flat or closed space sections, all of the cosmological spectral shift can be attributed to the non-flat connection (and thus indirectly to space-time curvature). For Robertson-Walker models with hyperbolic space sections, it is shown that cosmological spectral shifts uniquely split up into “kinematic” and “gravitational” parts provided that distances are small. For large distances no such unique split-up exists in general. A number of common, but incorrect assertions found in the literature regarding interpretations of cosmological spectral shifts, is pointed out.

scholarly journals Solvatochromic Study of Two Pyridazinium Ylids Binary Solutions

2016 ◽  
Vol 22 (3) ◽  
pp. 598-602
Author(s):  
Daniela Babuşca ◽  
Cezarina Ana Moroşanu ◽  
Dana Ortansa Dorohoi
Keyword(s):  
Solubility Parameter ◽  
Intramolecular Charge Transfer ◽  
Spectral Shift ◽  
Solvent Interactions ◽  
Binary Solutions ◽  
Spectral Shifts ◽  
Different Types ◽  
Linear Solvation Energy ◽  
Solvent Molecules ◽  
Parameter Values

Abstract The wavenumbers in the maximum of intramolecular charge transfer (ICT) visibile band of two pyridazinium ylids binary solutions were analized using Kamlet and Taft empirical parameters and the Hildebrand’s solubility parameter. The Hildebrand’s solubility parameter values, δH2, measures the energy needed to separate the solvent molecules. A linear solvation energy relationship (LSER) allows separating the contributions of different types of interactions to the total spectral shift. The supply of universal and specific interactions as well as the supply of solvent-solvent interactions to the total spectral shifts was calculated.

scholarly journals Graphical Optimization of Spectral Shift Reconstructions for Optical Backscatter Reflectometry

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6154
Author(s):  
Daniel C. Sweeney ◽  
Dennis M. Sweeney ◽  
Christian M. Petrie
Keyword(s):  
Adaptive Algorithm ◽  
Spanning Tree ◽  
Mechanical Strain ◽  
Adaptive Algorithms ◽  
Spectral Shift ◽  
Reference Measurement ◽  
Interferometric Technique ◽  
Quality Metric ◽  
Spectral Shifts ◽  
Maximum Spanning Tree

Optical backscatter reflectometry (OBR) is an interferometric technique that can be used to measure local changes in temperature and mechanical strain based on spectral analyses of backscattered light from a singlemode optical fiber. The technique uses Fourier analyses to resolve spectra resulting from reflections occurring over a discrete region along the fiber. These spectra are cross-correlated with reference spectra to calculate the relative spectral shifts between measurements. The maximum of the cross-correlated spectra—termed quality—is a metric that quantifies the degree of correlation between the two measurements. Recently, this quality metric was incorporated into an adaptive algorithm to (1) selectively vary the reference measurement until the quality exceeds a predefined threshold and (2) calculate incremental spectral shifts that can be summed to determine the spectral shift relative to the initial reference. Using a graphical (network) framework, this effort demonstrated the optimal reconstruction of distributed OBR measurements for all sensing locations using a maximum spanning tree (MST). By allowing the reference to vary as a function of both time and sensing location, the MST and other adaptive algorithms could resolve spectral shifts at some locations, even if others can no longer be resolved.

Influence of Tryptophan Modification upon Digestion of Antithrombin III by Elastase

1991 ◽  
Vol 65 (04) ◽  
pp. 351-354 ◽  
Author(s):  
M F Scully ◽  
N Shah ◽  
V Ellis ◽  
V V Kakkar
Keyword(s):  
Molecular Weight ◽  
Chemical Modification ◽  
Neutrophil Elastase ◽  
Antithrombin Iii ◽  
High Affinity ◽  
Tryptophan Residues ◽  
Tryptophan Modification ◽  
Modified Forms ◽  
Molecular Weight Form

SummaryChemical modification of tryptophan residues in antithrombin III by dimethyl (2-hydroxy-5-nitrobenzyl) sulfonium bromide (HNBSB) generates products with similar levels of modification (equivalent to 0.9 mole 2-hydroxy-5-nitrobenzyl [HNB] incorporated/mole of antithrombin III) but with high or low affinity for heparin-Sepharose. Upon digestion with pancreatic or neutrophil elastase the low affinity forms generate a product of molecular weight form (55 kDa) not seen in digests of native antithrombin III or modified forms with high affinity for heparin. When measured as loss of activity the obserued rate of digestion of the latter in the absence of heparin was more rapid than that of native antithrombin III. The differences in digestion are considered to be related to conformation at differences between the various forms.

Electromagnetic radiation and inertial forces

2019 ◽  
Vol 32 (4) ◽  
pp. 480-483
Author(s):  
Nasko Elektronov ◽  
Zhivko Kushev
Keyword(s):  
Electromagnetic Radiation ◽  
Doppler Effect ◽  
Inertial Force ◽  
Spectral Shift ◽  
Inertial Forces ◽  
Spectral Shifts ◽  
Nearby Stars ◽  
The Doppler Effect

The influence of the Coriolis inertial force generated by the orbital and spin motions of distant objects on the electromagnetic radiation energies during the exchange of photons between such objects has been considered. A red or blue spectral shift occurrence in a passive observation mode that is not associated with the Doppler effect or other known effects has also been shown. The relations found are used to calculate the spectral shifts for several nearby stars from our galaxy, as well as the spectral shifts of several galaxies. The results are close to the values currently observed.

scholarly journals Serological and fluorescence studies of the heat stability of bovine lactoferrin

1979 ◽  
Vol 46 (1) ◽  
pp. 83-93 ◽  
Author(s):  
Augustin Baer ◽  
Marko Oroz ◽  
Bernard Blanc
Keyword(s):  
Metal Binding ◽  
Binding Sites ◽  
Complement Fixation ◽  
Heat Stability ◽  
Heat Denaturation ◽  
Bovine Lactoferrin ◽  
Iron Binding ◽  
Binding Ability ◽  
Fluorescence Studies ◽  
Tryptophan Residues

SUMMARYThe heat denaturation of Fe-saturated lactoferrin (If) and Fe-free lactoferrin (apo-lf) was studied using the methods of micro-complement fixation and fluorescence. It was established that the change in conformation of apo-lf, induced by iron binding, conferred a higher heat stability to the molecule: the changes were observed at temperatures above 40 °C for apo-lf and above 60 °C for If. The Fe-binding ability of the protein was partially independent of the degree of denaturation. Fluorescence analyses indicated that tryptophan residues were probably not directly involved in the metal binding. There was no evidence of antibodies interfering with the binding sites.

Sign in / Sign up

Export Citation Format

Share Document