Finding a handle to bag the right proteins

September 09, 2020

Purifying specific protein molecules from complex mixtures will become easier with a simpler way to detect a molecular "tag" commonly used as a handle to grab the proteins.

Proteins, comprising many linked amino acid molecules, form the key "workforce" of molecular biology, performing a multitude of chemical tasks, including catalyzing the chemistry of life, switching genes on and off, and receiving and responding to signals between cells.

Researchers need to produce and purify selected proteins to investigate their activities for drug research, biotechnology and basic investigations of cell biology.

Proteins of interest are commonly made by inserting the genes that code for them into cells that will produce them, but that leaves the problem of identifying and purifying the desired protein from a potentially complex mixture. A common strategy is to modify the gene encoding the protein to make the protein carry a string of molecules of the amino acid called histidine, creating a "polyhistidine tag."

"The tag acts like a handle attached to a bag," explains the first author of the study, Vlad-Stefan Raducanu. "It's much easier to fish out a protein by catching the tag."

The various proteins in an impure sample can be separated using an electric field to pull them through a gel at different rates--a process called gel electrophoresis. The gel is then transferred to a membrane and the region carrying the polyhistidine-tagged proteins is visualized using antibodies, also a form of protein, to selectively bind to the tag. However, this type of detection can be laborious.

Now, Raducanu and his colleagues have developed a simpler detection procedure that avoids the membrane transfer step and the use of antibodies.

They constructed a chemical complex that binds to polyhistidine tags and can be stimulated by ultraviolet (UV) radiation to fluoresce with visible light. The regions of the gel carrying tagged proteins can be readily detected by the light given off by the UV-excited "fluorophore" complexes bound to the tags.

"It was challenging to devise a suitable UV-excitable fluorophore," Raducanu explains. The team had to couple the fluorescent component of their complex to another part containing a metal ion that can bind to the polyhistidine tag.

"We now plan to collaborate with chemists at KAUST to develop even brighter dyes," Raducanu says, expressing hope that the usefulness of UV-excitable fluorophores could be adopted more widely to help researchers detect the proteins they need.

King Abdullah University of Science & Technology (KAUST)

Related Proteins Articles from Brightsurf:

New understanding of how proteins operate
A ground-breaking discovery by Centenary Institute scientists has provided new understanding as to the nature of proteins and how they exist and operate in the human body.

Finding a handle to bag the right proteins
A method that lights up tags attached to selected proteins can help to purify the proteins from a mixed protein pool.

Designing vaccines from artificial proteins
EPFL scientists have developed a new computational approach to create artificial proteins, which showed promising results in vivo as functional vaccines.

New method to monitor Alzheimer's proteins
IBS-CINAP research team has reported a new method to identify the aggregation state of amyloid beta (Aβ) proteins in solution.

Composing new proteins with artificial intelligence
Scientists have long studied how to improve proteins or design new ones.

Hero proteins are here to save other proteins
Researchers at the University of Tokyo have discovered a new group of proteins, remarkable for their unusual shape and abilities to protect against protein clumps associated with neurodegenerative diseases in lab experiments.

Designer proteins
David Baker, Professor of Biochemistry at the University of Washington to speak at the AAAS 2020 session, 'Synthetic Biology: Digital Design of Living Systems.' Prof.

Gone fishin' -- for proteins
Casting lines into human cells to snag proteins, a team of Montreal researchers has solved a 20-year-old mystery of cell biology.

Coupled proteins
Researchers from Heidelberg University and Sendai University in Japan used new biotechnological methods to study how human cells react to and further process external signals.

Understanding the power of honey through its proteins
Honey is a culinary staple that can be found in kitchens around the world.

Read More: Proteins News and Proteins Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to