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- Ilagan, R P, et al.
(författare)
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Femtosecond time-resolved absorption spectroscopy of astaxanthin in solution and in alpha-crustacyanin
- 2005
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Ingår i: The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory. - : American Chemical Society (ACS). - 1520-5215. ; 109:14, s. 3120-3127
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Tidskriftsartikel (refereegranskat)abstract
- Steady-state absorption and femtosecond time-resolved spectroscopic studies have been carried out on astaxanthin dissolved in CS2, methanol, and acetonitrile, and in purified alpha-crustacyanin. The spectra of the S-0 -> S-2 and S-1 -> S-n transitions were found to be similarly dependent on solvent environment. The dynamics of the excited-state decay processes were analyzed with both single wavelength and global fitting procedures. In solution, the S-1 lifetime of astaxanthin was found to be similar to 5 ps and independent of solvent. In alpha-crustacyanin, the lifetime was noticeably shorter at similar to 1.8 ps. Both fitting procedures led to the conclusion that the lifetime of the S-2 state was either comparable to or shorter than the instrument response time. The data support the idea that dimerization of astaxanthin in alpha-crustacyanin is the primary molecular basis for the bathochromic shift of the S-0 -> S-2 and S-1 - S-n transitions. Planarization of the astaxanthin molecule, which leads to a longer effective pi-electron conjugated chain and a lower S-1 energy, accounts for the shorter tau(1) in the protein.
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- Knigge, U., et al.
(författare)
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ENETS Consensus Recommendations for the Standards of Care in Neuroendocrine Neoplasms : Follow-Up and Documentation
- 2017
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Ingår i: Neuroendocrinology. - : S. Karger AG. - 0028-3835 .- 1423-0194. ; 105:3, s. 310-319
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Tidskriftsartikel (refereegranskat)abstract
- ENETS consensus recommendations for the standards of care in neuroendocrine neoplasms (NEN) concerning follow-up and documentation are considered in this review. The documentation of patients with NEN should include the most relevant data characterizing an individual patient from the first contact with his/her physician/hospital until his/her last presentation during follow-up. It is advocated that follow-up occurs in specialized NEN centers with regular NEN tumor boards with expert panels. The follow-up should be in accordance with the ENETS consensus guidelines from 2011 and 2016, the present and coming WHO classification and ENETS/UICC recommendations for TNM staging. The recommendations for follow-up in patients with thymic, bronchopulmonary and gastroenteropancreatic NEN are given in Table 1. However, it should be stressed that evidence-based studies for follow-up are largely missing.
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- Polivka, Tomas, et al.
(författare)
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Spectroscopic properties of the carotenoid 3 '-hydroxyechinenone in the orange carotenoid protein from the cyanobacterium Arthrospira maxima
- 2005
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 44:10, s. 3994-4003
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Tidskriftsartikel (refereegranskat)abstract
- The cyanobacterial water-soluble orange carotenoid binding protein (OCP) is an ideal system for study of the effects of protein environment on photophysical properties of carotenoids. It contains a single pigment, the carotenoid 3'-hydoxyechinenone (hECN). In this study, we focus on spectroscopic properties of hECN in solution and in the OCP, aiming to elucidate the spectroscopic effects of the carotenoid-protein interaction in the context of the function(s) of the OCP. The noncovalent binding of hECN to the OCP causes a conformational change in the hECN, leading to a prolongation of the effective conjugation length. This change is responsible for shortening of the S, lifetime from 6.5 ps in solution to 3.3 ps in the OCP. The conformational change and the hydrogen bonding via the carbonyl group of hECN result in stabilization of an intramolecular charge-transfer (ICT) state. No signs of the ICT state were found in hECN in solution, regardless of the solvent polarity; spectral bands in transient absorption spectra of OCP-bound hECN exhibit features typical for the ICT state. Application of global fitting analysis revealed further effects of binding hECN in the OCP. The S, state of hECN in the OCP decays with two time constants of 0.9 and 3.3 ps. Modeling of the excited-state processes suggests that these two components are due to two populations of hECN in the OCP that differ in the hydrogen bonding via the carbonyl group. These results support the hypothesis that the OCP functions as a photoprotective shield under excess light. Mechanistically, the broadening of the hECN absorption spectrum upon binding to OCP enhances filtering, effect of hECN. Furthermore, the binding-induced conformational change and activation of the ICT state that leads to a shortening of hECN lifetime effectively makes the protein-bound hECN a more effective energy dissipator.
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- Smith, E L, et al.
(författare)
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Identification of a novel hepraglycosylceramide with two fucose residues and a terminal hexosamine.
- 1975
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Ingår i: Biochimica et biophysica acta. - 0006-3002. ; 398:1, s. 84-91
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Tidskriftsartikel (refereegranskat)abstract
- A polar fucose-containing glycosphingolipid fraction isolated from dog small intestine has been characterized by mass spectrometry of intact methylated, and methylated and reduced (LiAlH4) glycolipid. The native fraction, which was homogenous on thin-layer chromatography, was shown after methylation to be a mixture of two compounds. One was identified as a hexaglycoslyceramide with the following composition and sequence: fucose-hexose(fucose)-hexosamine-hexose-hexose-ceramide, with a terminal saccharide structure similar to blood group Leb determinants. The second compound was a novel heptaglycosyceramide with the sequence: hexosamine(fucose)-hexose-tfucose)-hexosamine-hexose-hexose-ceramide. This glycolipid was also detected in human small intestine and pancreas. The dog intestinal fraction had phytosphingosine as its major base and contained almost exclusively 2-hydroxy fatty acids (16 : 0--24 : 0). The fraction of human pancreas differed in having spingosine as its major base and normal fatty acids (16 : 0--24 :0) as major acids.
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