- Applications
- Physical background
- Technical data
- References
- Downloads
Applications
Below, examples are shown for intrinsic fluorescence imaging in crystallization plates of different types illuminated with white light and UV (blue)

Needle shaped crystals of a ribosome inactivating protein Type I. XtalLight was combined with an imaging system equipped with a CCD-video camera resolution: 1360 x 1036 pixel.

Needles of salt crystals in a NEXTAL QIA1 µplate (QIAGEN, Canada Inc.) Lot No. 2181002077, covered with standard sealing film. XtalLight was combined with an imaging system equipped with a CCD-video camera resolution: 1360 x 1036 pixel.
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Crystals of lysozyme as a hanging drop on a siliconized coverslip in a Linbro Plate (Hampton Research, HR3-110). XtalLight was combined with an imaging system equipped with a CCD-video camera resolution: 1360 x 1036 pixel. -
Needle shaped crystals of a protein-RNA complex among oily phase separation precipitate in a hanging drop. The drop hangs on a siliconized coverslip in a Linbro Plate (Hampton Research, HR3-110). XtalLight was combined with an imaging system equipped with a CCD-video camera resolution: 1360 x 1036 pixel. -
Crystals of the dihydrofolat reductase in a 96 Well, CrystalQuick COC plate (greiner bio-one, 609820). XtalLight was combined with an imaging system equipped with a CCD-video camera resolution: 1360 x 1036 pixel. -
A salt crystal in a NEXTAL QIA1 µplate (QIAGEN, Canada Inc.) Lot No. 2181002077, covered with standard sealing film. XtalLight was combined with an imaging system equipped with a CCD-video camera resolution: 1360 x 1036 pixel. -
A salt crystal in a NEXTAL QIA1 µplate (QIAGEN, Canada Inc.) Lot No. 2181002077, covered with standard sealing film. XtalLight was combined with an imaging system equipped with a CCD-video camera resolution: 1360 x 1036 pixel. -
Crystals of a ribosome inactivating protein type I, together with salt crystals in a hanging drop. The drop hangs on a siliconized coverslip in a Linbro Plate (Hampton Research, HR3-110). XtalLight was combined with an imaging system equipped with a with 1280 x 1024 DP-10 Digital Camera (Olympus). -
A Crystal of a unknown protein, in a hanging drop. The drop hangs on a siliconized coverslip in a Linbro Plate (Hampton Research, HR3-110). XtalLight was combined with an imaging system equipped with a CCD-video camera resolution: 1360 x 1036 pixel. -
Salt crystals among heavy precipitated protein and oily phase separation. The intrinsic fluorescence of the protein crystals is significantly more intense than the fluorescence light of the precipitant. The sample was in a 96 Well, CrystalQuick COC plate (greiner bio-one, 609820). -
Crystals of an unknown protein. The The sample was in a 96 Well, CrystalQuick COC plate (greiner bio-one, 609820) sealed with a standard sealing film. XtalLight was combined with an imaging system equipped with a CCD-video camera resolution: 1360 x 1036 pixel. -
Crystals of a ribosome inactivating protein type I. The The sample was in a 96 Well, CrystalQuick COC plate (greiner bio-one, 609820) sealed with a standard sealing film. XtalLight was combined with an imaging system equipped with a CCD-video camera resolution: 1360 x 1036 pixel.
Physical background

XtalLight 100 uses a filtered mercury arc lamp emission spectrum for intrinsic protein fluorescence excitation

Tryptophan fluorescence excitation is most efficient at 280 nm wavelength. The other aromatic aminoacids, tyrosine, phenylalanine and histidine, could only be excited at shorter wavelengths. Therefore they are of minor importance for in situ intrinsic fluorescence crystal detection (Figure 2).

The opacity of glas coverslips and sealing films reduce the light intensity significantly (Figure 3). Howerver, the characteristics of a filtered mercury arc lamp spectrum compensates the weak opacity and is still sufficient to excite tryptophan fluorescence.

Tryptophan fluorescence is shown in three images of the same glucose isomerase crystal as sitting drop in a 96 Well, CrystalQuick COC plate (greiner bio-one, 609820). All three images were taken using the same exposure time and light sensitivity. On top, the crystal was covered with a quartz cover slip (suprasil). The relative excitation spectrum intensity was calculated for three different proteins (product of the transmission spectrum with the specific molar absorption of the protein) shown on the left side. In the middle the crystal was covered with a standard polymeric film and below with a common glas cover slip. The opacity for wavelengths below 300 nm is significantly reduced when the crystal is covered by glas. However, the appearance of the intrinsic fluorescence seems almost identical, when illuminated with a filtered mercury arc lamp spectrum.
Technical Data
UV light source |
Mercury arc lamp with 120 W
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Filter |
Motorised filter change up to three positions:
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Control |
Control of UV light intensity, filter setting and shutter
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Light guide |
Light guide for UV light 1.5 mm core diameter
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UV light optics |
Focusing optics for directing UV light onto the sample
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Hardware |
Table-top case
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Imaging package (optional) |
Computer
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Colour CCD camera Camera for adaptation to a microscope
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Imaging SW
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Positioning and protection |
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Adaptable Microscopes |
Adaptable to several microscopes depending on working distance and set-up |
Suitable plates and sealing films |
Crystallization plates with low intrinsic fluorescence (low birefringence) and UV suitable sealing films |
References
Efficient UV detection of protein crystals enabled by fluorescence excitation at wavelengths longer than 300 nm