| 1. |
- Bhalerao, RP, et al.
(författare)
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Structure and energy-transfer of the phycobilisome in a linker protein replacement mutant of cyanobacterium synechococcus-7942
- 1991
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Ingår i: Biochimica et Biophysica Acta. - 0006-3002 .- 1878-2434. ; 1060:1, s. 59-66
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Tidskriftsartikel (refereegranskat)abstract
- The role of the linker proteins in the biogenesis and energy transfer of the phycobilisome rod was monitored by making insertional inactivation in the cpcI gene coding for the core-proximal 33 kilodalton (kDa) protein in the cyanobacterium Synechococcus 7942. The insertion leaves the cpcH gene coding for the core-distal 30 kDa protein intact and functional. Analysis of the phycobilisome protein composition of the cpcI mutant shows that the 30 kDa protein is present in normal amounts in the rod, indicating that the 30 kDa linker protein can replace the 33 kDa protein in the biogenesis and structural integrity of the rod. The absorption and fluorescence characteristics of the mutated phycobilisome is almost indistinguishable from that of the wild-type of the same rod length. The fluorescence kinetics from the cpcI mutant show that the dominating decay component has a lifetime from phycocyanin of 69 ps as compared to 72 ps found for the wild-type phycobilisome with the same rod length. The results show that replacing the 33 kDa for the 30 kDa linker in the rod does not alter the energy harvesting or the energy transfer characteristics of the rod in contrast to what has been concluded from data obtained from in vitro experiments. We conclude that the linker polypeptides have only a minor influence on the energy transfer characteristics of the rod but are mainly involved in determining the length of the rod in response to changing environmental light conditions.
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| 2. |
- Gillbro, J. M., et al.
(författare)
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In vivo topical application of acetyl aspartic acid increases fibrillin-1 and collagen IV deposition leading to a significant improvement of skin firmness
- 2015
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Ingår i: International Journal of Cosmetic Science. - : Wiley. - 0142-5463 .- 1468-2494. ; 37, s. 41-46
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Tidskriftsartikel (refereegranskat)abstract
- Synopsis ObjectiveAcetyl aspartic acid (A-A-A) was discovered through gene array analysis with corresponding Cmap analysis. We found that A-A-A increased keratinocyte regeneration, inhibited dermal matrix metalloprotease (MMP) expression and relieved fibroblast stiffness through reduction of the fibroblast stiffness marker F-actin. Dermal absorption studies showed successful delivery to both the epidermal and dermal regions, and in-use trial demonstrated that 1% A-A-A was well tolerated. In this study, the aim was to investigate whether A-A-A could stimulate the synthesis of extracellular matrix supporting proteins invivo and thereby improving the viscoelastic properties of human skin by conducting a dual histological and biophysical clinical study. MethodTwo separate double-blind vehicle-controlled invivo studies were conducted using a 1% A-A-A containing oil-in-water (o/w) emulsion. In the histological study, 16 female volunteers (>55years of age) exhibiting photodamaged skin on their forearm were included, investigating the effect of a 12-day treatment of A-A-A on collagen IV (COLIV) and fibrillin-1. In a subsequent pilot study, 0.1% retinol was used for comparison to A-A-A (1%). The biomechanical properties of the skin were assessed in a panel of 16 women (>45years of age) using the standard Cutometer MPA580 after topical application of the test products for 28days. The use of multiple suction enabled the assessment of F4, an area parameter specifically representing skin firmness. ResultsTwelve-day topical application of 1% A-A-A significantly increased COLIV and fibrillin with 13% and 6%, respectively, compared to vehicle. 1% A-A-A and 0.1% retinol were found to significantly reduce F4 after 28days of treatment by 15.8% and 14.7%, respectively, in the pilot Cutometer study. No significant difference was found between retinol and A-A-A. However, only A-A-A exhibited a significant effect vs. vehicle on skin firmness which indicated the incremental benefit of A-A-A as a skin-firming active ingredient. ConclusionIn this study, we showed the invivo efficacy of 1% A-A-A both on a protein level (fibrillin and collagen IV) and on a clinical end point, specifically skin firmness, providing proof that, acetyl aspartic acid has a strong potential as an anti-ageing cosmeceutical' ingredient answering the needs of our key consumer base. Resume ObjectifL'acide aspartique acetyle (A-A-A) a ete identifie en utilisant la technologie de puces a ADN combine a une analyse en connectivity mapping' (Cmap), pour ces potentielles proprietes anti-age. A-A-A a la capacite d'augmenter la regeneration cellulaire et d'inhiber l'expression des MMP, ainsi que reduire la rigidite des fibroblastes en depolymerisant le reseau d'actine. Les etudes d'absorption cutanee ont montre une tres bonne biodisponibilite tant dans l'epiderme que le derme et les etudes de securite on confirme une tres bonne tolerance cutanee de A-A-A. Dans cette etude, nous avons cherche a demontrer que A-A-A pouvait stimuler la synthese des proteines de la matrice extra-cellulaire ainsi qu'ameliorer les proprietes viscoelastiques de la peau humaine en procedant a une double etude clinique, par immunohistochimie et biophysique sur volontaires. MethodesLes deux etudes on ete realisees en double aveugle contre placebo avec une emulsion H/E contenant 1% A-A-A. L'etude histologique a ete realisee sur 16 femmes volontaires (>55ans) presentant des signes de photoveillissement sur l'avant-bras durant une periode de 12 jours sur l'expression du collagene IV (COLIV) et de la fibrilline-1. Dans la seconde etude, les proprietes biomecaniques de la peau ont ete evaluees dans un panel de 16 femmes (>45ans) utilisant le Cutometre MPA580 et en mesurant le parametre F4, valeur representant specifiquement la fermete de la peau, apres l'application topique de produits durant pour 28 jours. Pour cette etude A-A-A (1%) a ete compare, en plus du placebo, a une formulation contenant 0.1% de retinol. ResultatsApres 12 jours d'application topique de 1% A-A-A, nous avons pu demontre une augmentation significative de l'expression de COLIV et de la fibrilline respectivement 13% et 6% par rapport au placebo. L'application de 1% A-A-A et 0,1% de retinol ont permis de pour reduire significativement F4 apres 28 jours de traitement respectivement de 15.8% et 14.7%. Aucune difference significative n'a ete trouvee entre le retinol et A-A-A. Cependant, seul A-A-A presentait une ameloration significative sur la fermete de la peau, ce qui confime le benefice apporte par A-A-A comme actif stimulant le raffermissement de la peau. ConclusionDans cette etude, nous avons montre l'efficacite de 1% A-A-A a la fois invivo sur l'expression des proteines (fibrilline et collagene IV) et sur un parametre clinique specifiquement lie a la fermete de la peau. Ces deux etudes confirment que l'acide acetyl-aspartique a un fort potentiel en tant qu' agent anti-age pouvant aussi etre considere comme un ingredient cosmeceutique' repondant aux besoins des consommateurs en demande de produits cosmetiques a efficacite prouvee.
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| 3. |
- Kilså, Kristine, 1972, et al.
(författare)
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Control of electron transfer in supramolecular systems
- 2001
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Ingår i: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy. - 1386-1425. ; 57:11, s. 2213-2227
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Tidskriftsartikel (refereegranskat)abstract
- The fluorescence quantum yield of zinc porphyrin (ZnP) covalently linked to 9,10-bis(phenylethynyl)anthracene (AB) is strongly dependent upon the solvent properties. The bichromophoric system ZnP-AB exhibits 'normal' zinc porphyrin fluorescence in solvents that cannot coordinate to the central zinc atom. In contrast, if a Lewis base, such as pyridine, is added to a sufficiently polar solvent, the fluorescence is significantly quenched. Picosecond transient absorption measurements, in conjunction with fluorescence quenching and cyclic voltammetric measurements, suggest that the quenching mechanism is intramolecular electron transfer from ZnP to AB. The charge separated state, ZnP.+-AB(.-), has a lifetime of not more than 220 ps before recombining. If a secondary electron acceptor, iron(III) porphyrin (FeP), is covalently connected to the AB unit, a second electron transfer from AB(.-) to FeP occurs and the charge separated state, ZnP.+-AB-FeP.-, has a lifetime of at least 5 ns. This demonstrates that electron transfer might be sensitively tuned (switched on) by specific solvent effects. (C) 2001 Elsevier Science BN. All rights reserved.
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| 4. |
- Neerken, S, et al.
(författare)
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Kinetics of absorbance and anisotropy upon excited state relaxation in the reaction center core complex of a green sulfur bacterium
- 2000
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Ingår i: Photosynthesis Research. ; 65:3, s. 261-8
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Tidskriftsartikel (refereegranskat)abstract
- Properties of the excited states in reaction center core (RCC) complexes of the green sulfur bacterium Prosthecochloris aestuarii were studied by means of femtosecond time-resolved isotropic and anisotropic absorption difference spectroscopy at 275 K. Selective excitation of the different transitions of the complex resulted in the rapid establishment of a thermal equilibrium. At about 1 ps after excitation, the energy was located at the lowest energy transition, BChl a 835. Time constants varying between 0.26 and 0.46 ps were observed for the energy transfer steps leading to this equilibrium. These transfer steps were also reflected in changes in polarization. Our measurements indicate that downhill energy transfer towards excited BChl a 835 occurs via the energetically higher spectral forms BChl a 809 and BChl a 820. Low values of the anisotropy of about 0.07 were found in the `two-color' measurements at 820 and 835 nm upon excitation at 800 nm, whereas the `one-color' kinetics showed much higher anisotropies. Charge separation occurred with a time constant varying between 20 and 30 ps.
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| 5. |
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