Infrared spectroscopy of phytochrome and model pigments

Fourier-transform infrared difference spectra between the red-absorbing and far-red-absorbing forms of oat phytochrome have been measured in H2O and 2H2O. The difference spectra are compared with infrared spectra of model compounds, i.e. the (5Z,10Z,15Z)- and (5Z,10Z,15E)-isomers of 2,3,7,8,12,13,17,18-octaethyl-bilindion (Et8-bilindion), 2,3-dihydro-2,3,7,8,12,13,17,18-octaethyl-bilindion (H2Et8-bilindion), and protonated H2Et8-bilindion in various solvents. The spectra of the model compounds show that only for the protonated forms can clear differences between the two isomers be detected. Since considerable differences are present between the spectra of Et8-bilindion and H2Et8-bilindion, it is concluded that only the latter compound can serve as a model system of phytochrome. The 2H2O effect on the difference spectrum of phytochrome supports the view that the chromophore in red-absorbing phytochrome is protonated and suggests, in addition, that it is also protonated in far-red-absorbing phytochrome. The spectra show that protonated carboxyl groups are influenced. The small amplitudes in the difference spectra exclude major changes of protein secondary structure

As Origens da Medicina Ocidental: Mesopotâmia e Egito Antigo / The Origins of Western Medicine: Mesopotamia and Ancient Egypt

Não é possível compreender a Medicina, sua prática e símbolos sem conhecer seus caminhos na história. A nobre arte de curar não nasceu de repente, sua jornada milenar envolve a contribuição de diversos povos e culturas que proporcionaram subsídios para seu desenvolvimento até a atualidade. O presente estudo objetivou identificar a origem do símbolo da medicina atual e a importância das civilizações mesopotâmica e egípcia na evolução do conhecimento médico ocidental, cada uma com suas particularidades. A pesquisa envolveu, além de aspectos históricos, a influência da religião nos feitos curativos e como a sociedade enxergava o processo saúde-doença. O artigo conta como a prática médica antiga foi preservada, possibilitando os conhecimentos atuais, na mesopotâmia a partir dos tabletes da coleção de Assurbanipal grafados pela escrita cuneiforme e, no Egito Antigo por escritos em papiro

A prática médica na Grécia Antiga e a influência da mitologia no processo de cura / Medical practice in ancient Greece and the influence of mythology on the healing process

O presente artigo tem como objetivo demonstrar a importância da civilização grega na construção e evolução do conhecimento médico. O estudo ressalta a interdisciplinaridade da compreensão humana do período, sobretudo com o advento da filosofia, que permitiu a abertura de questionamentos sobre o universo e a responsabilidade exclusiva da religião sobre o processo saúde-doença, o que rompe com a crença de que seres ocultos e feitiços atuem como ocasionadores de enfermidade. Além disso, este artigo aborda a mitologia grega e a influência dela sobre as práticas médicas realizadas na Grécia Antiga, expondo a crença em Asclépio, centauro Quíron, Higéia e Panacéia nas atividades curativas. O estudo ainda discorre sobre Hipócrates, considerado pai da medicina e responsável por uma vasta coleção chamada Corpus Hipocraticum, conhecido mundialmente, e do qual herdamos o Juramento de Hipócrates, utilizado até os dias atuais para o ingresso na profissão médica

The past and future of enzyme measurements using surface enhanced Raman spectroscopy

The ability to accurately and sensitively measure the activity of specific enzymes is central to many aspects of modern chemistry and when combined with new nanoscience based approaches, offers significant opportunities for advancing other scientific disciplines. We review the development of surface enhanced resonance Raman scattering (SERRS) for the detection of enzymes, from the initial direct spectroscopy of enzymes, substrate/product and inhibitors adsorbed onto metallic colloids, to the current approach of measuring enzymatic activity by recording the SERRS spectra of a product which is only 'switched on' after enzyme activity. Developments focussed on improvements to modular masked SERRS substrates, which are unmasked by specific enzymes, are also reviewed. Finally, we set out the remaining grand challenges within the area of enzymatic analysis by SERRS which include single molecule detection, in vivo studies and increased multiplexing for screening of evolved enzyme libraries

Surface science of soft scorpionates

The chemisorption of the soft scorpionate Li[PhTmMe] onto silver and gold surfaces is reported. Surface enhanced Raman spectroscopy in combination with the Raman analysis of suitable structural models, namely, [Cu(κ3-S,S,S-PhTmMe)(PCy3)], [Ag(κ3-S,S,S-PhTmMe)(PCy3)], [Ag(κ2-S,S-PhTmMe)(PEt3)], and [Au(κ1-S-PhTmMe)(PCy3)], are employed to identify the manner in which this potentially tridentate ligand binds to these surfaces. On colloidal silver surface-enhanced Raman spectroscopy (SERS) spectra are consistent with PhTmMe binding in a didentate fashion to the surface, holding the aryl group in close proximity to the surface. In contrast, on gold colloid, we observe that the species prefers a monodentate coordination in which the aryl group is not in close proximity to the surface

Surface enhanced resonance Raman scattering as a probe of the spin state of structurally related cytochromes P-450 from rat liver

AbstractSurface enhanced resonance Raman scattering (SERRS) was observed from structurally related drug-induced rat liver cytochromes P-450 adsorbed on a silver colloid. Careful control of pH and the sequence of addition of components to the sol is required to prevent protein denaturation at the surface due to conversion to P-450's biologically inactive form P-420 or haem loss. A low-spin P-450 (PB3a), a mixed low-and high-spin P-450 (PB3b) and a predominantly high-spin P-450 (MC1a) were investigated. Spectra recorded in the 1300–1700 cm−1 frequency region, containing the oxidation state marker ν4 at 1375 cm−1 (Fe3+) and spin state markers ν10 (1625 cm−1, high-spin; 1633 cm−1, low-spin) and ν19 (1575 cm−1, high-spin; 1585 cm−1, low-spin) were used to differentiate between the spin states of the various forms of cytochrome P-450. As well as the established spin state marker bands, the intensity of a band at 1400 cm−1 appeared to depend on the high-spin content. Thus, with this method SERRS from silver colloids can be used to determine spin states of related cytochromes P-450 in dilute solution (10−8 M) and may be of value in studies of protein-substrate interactions