Schiff Base Protonation Changes in Siberian Hamster Ultraviolet Cone Pigment Photointermediates

Mooney, Victoria; Szundi, István; Lewis, James W.; Yan, Elsa C. Y.; Kliger, David S.

doi:10.1021/bi300157r

Cited by 21 publications

(15 citation statements)

References 36 publications

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“…Schiff bases are among the most widely used organic compounds, exhibiting a broad range of applications, such as intermediates in organic synthesis [4][5][6][7], chemosensors [8][9][10] and polymer stabilisers [11][12][13], in food industry [14,15], as dye [16][17][18] and pigments [19][20][21], catalysis [22,23] and others [24][25][26]. Schiff bases also present a broad range of biological activities [27][28][29][30] for which the azomethine or imine group present in their structures, seems to play a critical role [31][32][33].…”

Section: Figmentioning

confidence: 99%

Recent developments in penta-, hexa- and heptadentate Schiff base ligands and their metal complexes

Liu

Hamon

2019

Coordination Chemistry Reviews

320

137

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Novel ligand platforms that promote reactivity are of long standing and continued interest in coordination chemistry, with Schiff base ligands and their metal complexes representing one of the most versatile and long standing topics of interest. The synthesis and structure of polydentate Schiff bases and their metal complexes is fascinating, because it reveals a great richness of structural, physico-chemical and catalytic properties. Given the simplicity and ease of access to multidentate Schiff bases and their metal complexes, investigation of such compounds is essential to precise and understand structure-property relationships in order to optimize and improve their use in a wide range of fields, including catalysis, supramolecular chemistry, magnetism, electrochemistry, nanoscience, energy materials, and biological applications. This review highlights the recent developments of pentadentate, hexadentate, heptadentate and macrocyclic Schiff base ligands containing various donor sets made of different combinations of N, O, S or P donor atoms and their metal complexes (essentially mononuclear), as well as presenting synthetic methods and interesting structures of complexes formed by first-to-third row transition metals (from group 4-12), main group elements, lanthanides and actinides. This review is divided into three main sections, each of them corresponding to one type of denticity of the Schiff base under consideration. Each category is described with representative examples according to a periodic order, and emphasis is given to the coordination aspects. Their catalytic, magnetic and biological properties are also outlined. This review that contains 359 references should act as a source of information to researchers interested to work in this domain and stimulate further investigation in this fascinating area of Schiff base coordination compounds.

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Section: Figmentioning

confidence: 99%

Recent developments in penta-, hexa- and heptadentate Schiff base ligands and their metal complexes

Liu

Hamon

2019

Coordination Chemistry Reviews

320

137

View full text Add to dashboard Cite

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“…In SWS1 pigments, four of these residues are identical to those found in rods, and there are no differences at these sites between UV‐sensitive (UVS) and violet‐sensitive (VS) SWS1. The structural factors that determine this distinct protonation state of the chromophore in UVS pigments have not yet been fully elucidated at the molecular level, though a recent study has implicated water molecules participating in the E113 bond network in a mammalian UV pigment (Mooney et al, ). The absence of Schiff base protonation in UVS SWS1 is particularly intriguing because it eliminates one of the dark‐state activation barriers that is present in all other visual pigment classes: ionic interactions between the protonated Schiff base linkage and the counterion are thought to suppress activation of the second messenger G protein transducin.…”

Section: Spectral Tuning In Visual Pigmentsmentioning

confidence: 99%

“…How constitutive activity is suppressed in UV pigments with an unprotonated Schiff base linkage is unclear, but there is evidence that E113 is still involved, as this residue is conserved even in UV pigments (Kono, ). Subsequent protonation of the light‐activated photointermediate occurs prior to the formation of the transducin‐activating metarhodopsin II state in all visual pigments, including UVS SWS1 (Kusnetzow et al, ; Mooney et al, ). Though we focus on spectral tuning mechanisms in this review, UVS and VS SWS1 pigments also differ in other physicochemical characteristics aside from absorption maxima, and these differences are likely influenced by the protonation state of the Schiff base.…”

Section: Spectral Tuning In Visual Pigmentsmentioning

confidence: 99%

Spectral tuning in vertebrate short wavelength‐sensitive 1 (SWS1) visual pigments: Can wavelength sensitivity be inferred from sequence data?

2014

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The molecular mechanisms underlying the enormous diversity of visual pigment wavelength sensitivities found in nature have been the focus of many molecular evolutionary studies, with particular attention to the short wavelength-sensitive 1 (SWS1) visual pigments that mediate vision in the ultraviolet to violet range of the electromagnetic spectrum. Over a decade of study has revealed that the remarkable extension of SWS1 absorption maxima (λ max ) into the ultraviolet occurs through a deprotonation of the Schiff base linkage of the retinal chromophore, a mechanism unique to this visual pigment type. In studies of visual ecology, there has been mounting interest in inferring visual sensitivity at short wavelengths, given the importance of UV signaling in courtship displays and other behaviors. Since experimentally determining spectral sensitivities can be both challenging and time-consuming, alternative strategies such as estimating λ max based on amino acids at sites known to affect spectral tuning are becoming increasingly common. However, these estimates should be made with knowledge of the limitations inherent in these approaches. Here, we provide an overview of the current literature on SWS1 site-directed mutagenesis spectral tuning studies, and discuss methodological caveats specific to the SWS1-type pigments. We focus particular attention on contrasting avian and mammalian SWS1 spectral tuning mechanisms, which are the best studied among vertebrates. We find that avian SWS1 visual pigment spectral tuning mechanisms are fairly consistent, and therefore more predictable in terms of wavelength absorption maxima, whereas mammalian pigments are not well suited to predictions of λ max from sequence data alone.

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“…Uniquely however, UVS pigments have an unprotonated SB (Babu et al, 2001 ;Shi et al, 2001 ;Fasick et al, 2002 ;Mooney et al 2012 ); the protonation state of SWS1 pigments differs therefore and is linked directly to spectral sensitivity. Uniquely however, UVS pigments have an unprotonated SB (Babu et al, 2001 ;Shi et al, 2001 ;Fasick et al, 2002 ;Mooney et al 2012 ); the protonation state of SWS1 pigments differs therefore and is linked directly to spectral sensitivity.…”

Section: Tuning Of Sws1 Pigmentsmentioning

confidence: 99%

S cones: Evolution, retinal distribution, development, and spectral sensitivity

Hunt

Peichl

2013

Vis Neurosci

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S cones expressing the short wavelength-sensitive type 1 (SWS1) class of visual pigment generally form only a minority type of cone photoreceptor within the vertebrate duplex retina. Hence, their primary role is in color vision, not in high acuity vision. In mammals, S cones may be present as a constant fraction of the cones across the retina, may be restricted to certain regions of the retina or may form a gradient across the retina, and in some species, there is coexpression of SWS1 and the long wavelength-sensitive (LWS) class of pigment in many cones. During retinal development, SWS1 opsin expression generally precedes that of LWS opsin, and evidence from genetic studies indicates that the S cone pathway may be the default pathway for cone development. With the notable exception of the cartilaginous fishes, where S cones appear to be absent, they are present in representative species from all other vertebrate classes. S cone loss is not, however, uncommon; they are absent from most aquatic mammals and from some but not all nocturnal terrestrial species. The peak spectral sensitivity of S cones depends on the spectral characteristics of the pigment present. Evidence from the study of agnathans and teleost fishes indicates that the ancestral vertebrate SWS1 pigment was ultraviolet (UV) sensitive with a peak around 360 nm, but this has shifted into the violet region of the spectrum (>380 nm) on many separate occasions during vertebrate evolution. In all cases, the shift was generated by just one or a few replacements in tuning-relevant residues. Only in the avian lineage has tuning moved in the opposite direction, with the reinvention of UV-sensitive pigments.

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Schiff Base Protonation Changes in Siberian Hamster Ultraviolet Cone Pigment Photointermediates

Cited by 21 publications

References 36 publications

Recent developments in penta-, hexa- and heptadentate Schiff base ligands and their metal complexes

Recent developments in penta-, hexa- and heptadentate Schiff base ligands and their metal complexes

Spectral tuning in vertebrate short wavelength‐sensitive 1 (SWS1) visual pigments: Can wavelength sensitivity be inferred from sequence data?

S cones: Evolution, retinal distribution, development, and spectral sensitivity

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