Luminescence shines new light on proteins

Nov 11, 2008

A chance discovery by a team of scientists using optical probes means that changes in cells in the human body could now be seen in a completely different light.

Prof David Parker from Durham University's Chemistry Department was working with experts from Glasgow University, and a team of international researchers, when they discovered dramatic changes in the way that light was emitted by optical probes during a series of experiments.

Light has energy and carries information and the researchers used the optical probes to measure the behaviour of light and its interaction with proteins abundant in human blood. The fortuitous discovery has led to the creation of a new type of probe for examining protein interactions that could be used for cellular imaging.

By tracking the way in which proteins bind, the experiments will aid understanding of the function of the most abundant protein in the body, serum albumin. In the future the technique could help to understand how drugs used in medicine interact with the major protein found in blood.

Prof Parker says: "It's a new step in the development of optical probes in chemistry and in observing the interaction between medical drugs and proteins."

The Durham University-led team looked at how light behaved when serum albumin was added to the probes and found that the emitted polarised light had interesting characteristics.

Chirality, or handedness, is a key concept in Nature. In molecular chemistry, it refers to the concept of a molecule having two mirror images that cannot be superimposed onto each other; these are called enantiomers and pairs of these can be designated as 'right-' and 'left-handed.'

Light can be thought of as being made up of two left and right handed components and this property can be measured. The research team used optical probes with hi-spatial resolution and precision to track protein interactions and to see how the light rotates and inverts when passed through the proteins.

Prof Parker says: "We have found a way to use the inherent chirality of light to examine the interaction at the molecular level between a probe (the optical probe, itself of one handedness) and serum albumin (also of one handedness: hence akin to a hand/glove interaction) - the most abundant protein in blood."

Based on a chiral lanthanide complex, the probe emits circularly polarised light that inverts sign on protein binding; monitoring the emitted light allows researchers to follow the interaction between the complex and the protein.

Observing this luminescence is a way of studying the chirality of the system, explains Prof Parker: "The optical signal we observed carries information in its circular polarisation. It's a tricky process. You have to get the light in and out of the cells but crucially, in terms of biology, it can be done using microscopes in the laboratory so it's non-invasive."

The researchers found that only one enantiomer of certain europium and terbium complexes bound selectively to a drug binding site of the protein serum albumin, and that the luminescence changed dramatically. Prof Parker says: "This is the first example of chiral inversion using an emissive probe in this way."

The researchers have been seeking to develop responsive optical probes for a while and were delighted when they finally cracked it.

Prof Parker said: "We were genuinely surprised. The binding energy and kinetics have to be just right - we've been lucky. Potentially this technology could be used to track protein association in living cells in real time."

Source: Durham University

Explore further: Team pioneers strategy for creating new materials

add to favorites email to friend print save as pdf

Related Stories

3-D microscope method to look inside brains

Aug 14, 2014

(Phys.org) —A University of Utah team discovered a method for turning a small, $40 needle into a 3-D microscope capable of taking images up to 70 times smaller than the width of a human hair. This new method ...

Inside the cell, an ocean of buffeting waves

Aug 14, 2014

Conventional wisdom holds that the cytoplasm of mammalian cells is a viscous fluid, with organelles and proteins suspended within it, jiggling against one another and drifting at random. However, a new biophysical ...

3-in-1 optical skin cancer probe

Aug 05, 2014

As thousands of vacationers hit the beach this summer, many of them will expose their unprotected bare limbs to direct UV sunlight, potentially putting them at risk of skin cancer later in life. To fight ...

Biology made simpler with "clear" tissues

Aug 04, 2014

(Phys.org) —In general, our knowledge of biology—and much of science in general—is limited by our ability to actually see things. Researchers who study developmental problems and disease, in particular, ...

Recommended for you

Team pioneers strategy for creating new materials

Aug 29, 2014

Making something new is never easy. Scientists constantly theorize about new materials, but when the material is manufactured it doesn't always work as expected. To create a new strategy for designing materials, ...

Plug n' Play protein crystals

Aug 29, 2014

Almost a hundred years ago in 1929 Linus Pauling presented the famous Pauling's Rules to describe the principles governing the structure of complex ionic crystals. These rules essentially describe how the ...

Protein glue shows potential for use with biomaterials

Aug 28, 2014

Researchers at the University of Milan in Italy have shown that a synthetic protein called AGMA1 has the potential to promote the adhesion of brain cells in a laboratory setting. This could prove helpful ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

E_L_Earnhardt
3 / 5 (2) Nov 11, 2008
A truly great breakthrough! Protein construction is a mystery we must solve to go on!