Study: Crystal structures of fluorescent proteins determined
Researchers have determined the crystal structures of red fluorescent protein TagRFP and its derivative, the blue fluorescent protein mTagBFP and have proposed a chemical mechanism by which the red color in fluorescent proteins is formed from blue, according to study results published April 23 in Chemistry & Biology.

Vladislav V. Verkhusha, PhD, associate professor of anatomy and structural biology at Albert Einstein College of Medicine in Bronx, N.Y., demonstrated that mTagBFP was a new type of the chromophore, N-[(5-hydroxy-1H-imidazole-2-yl) methylidene] acetamide.

The researchers also proposed a chemical mechanism in which the red-like chromophore is formed via the mTagBFP-like blue intermediate.

“Knowing the molecular structures of the chromophores--the part of fluorescent protein molecules that gives them their color--we can now do hypothesis-based designing of new probes, instead of relying on random mutations,” said Verkhusha.

Researchers can now follow only two or three proteins at a time. “To understand many cellular functions, you would like to follow dozens of different proteins, so the more colors we can develop, the better,” said study co-author Steven C. Almo, PhD, professor of biochemistry and of physiology and biophysics at Albert Einstein.

Using this new information, Verkhusha’s laboratory has already designed a variety of new fluorescent proteins that can glow in colors ranging from blue to far-red and recently viewed individual breast cancer cells for several days at a time to study metastasis.