Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hopkins scientists overcome main obstacle to making tons of short, drug-like proteins

23.04.2004


Two Johns Hopkins scientists have figured out a simple way to make millions upon millions of drug-like peptides quickly and efficiently, overcoming a major hurdle to creating and screening huge "libraries" of these super-short proteins for use in drug development.



"Our work dramatically increases the complexity of peptide libraries that can be created and the speed with which they can be made and processed," says Chuck Merryman, Ph.D., a postdoctoral fellow who developed the new technique. "In an afternoon, we’ll be able to make literally millions of millions of different peptides with medicinal potential."

Usually less than 40 building blocks long, peptides act as important messengers and hormones in the body. But because their building blocks, called amino acids, are quickly recycled, peptides made from the 20 naturally occurring amino acids don’t last long enough to be useful as medicines. However, adding a tiny methyl group to each amino acid gives the resulting peptide "drug-like" stability.


Writing in the April 19 issue of Chemistry & Biology, the Hopkins scientists reveal that using a simple chemical reaction, first reported in the early 1980s, allows them to convert en masse the naturally occurring amino acids to ones that form more stable peptides.

The tricky part, Merryman says, was figuring out how to do the conversion while the amino acids were attached to transfer RNA, a carrier molecule required for the biological production of peptides. The advance makes it possible to build upwards of 10,000,000,000,000 -- that’s 1 with 13 zeros behind it -- stabilized, 10-block-long peptides at once.

"The idea of creating large peptide libraries and testing them for medicinal uses has been around a long time, but until now it’s just not been very practical," says Merryman.

A key aspect of all scientists’ efforts to create libraries of drug-like peptides is "biology in a dish" -- harnessing the same machinery cells use to read genetic instructions and assemble correct proteins. Since at least the 1970s, scientists have known that this machinery, called the ribosome, also can string together a wide variety of artificial amino acids, as long as the fake building block is tied to transfer RNA that the ribosome can use to "decode" genetic information.

"There are a number of steps to the process of building peptides, natural or not, and each one has created problems for building large libraries of random drug-like peptides," says Merryman.

A complex of RNA and proteins, the ribosome "reads" three-bit sections of messenger RNA and recruits a complementary three-bit-containing piece of transfer RNA, which is attached to its corresponding amino acid. The ribosome’s machinery then chops off the amino acid and adds it to the growing peptide string.

To harness this natural process to do their bidding, scientists have tried to make various artificial amino acids attached to transfer RNA, and to have the ribosome use those novel components while reading genetic instructions, the messenger RNA.

"There’s been some success, but no one’s been able to do this with multiple artificial amino acids at once or to create very large numbers of peptides that are entirely artificial," says Merryman.

Merryman starts with a mixture of the 20 naturally occurring amino acids, already tethered to their transfer RNA sequences. In the new process, a first chemical step temporarily protects one reactive side of the exposed nitrogen atom of the amino acid, and a second step adds the methyl group to the nitrogen’s other open spot. The final step uses ultraviolet light to remove the protecting group added in step one.

The result is a single pot of the 20 natural amino acids, still attached to the appropriate tRNAs, but 19 of them now with that all-important methyl group. (One amino acid, proline, remains unchanged -- once its nitrogen is protected, there’s no room for the methyl group.)

"It’s pretty simple chemistry, and it’s kind of amazing it hadn’t already been applied to this problem," says Merryman. "The process gave us efficient and essentially complete conversion to the modified amino acids. Since the process works the same for all amino acids, you don’t have to treat each one separately and then mix them at the end, which speeds things up considerably."

Merryman and mentor Rachel Green, Ph.D., an associate professor of molecular biology and genetics and an associate investigator of the Howard Hughes Medical Institute, have a patent on the synthetic process under review at the U.S. Patent and Trademark Office.

To make a peptide library from the pot of modified amino acids, researchers would mix the pot with ribosomes and random sequence messenger RNAs that reflect the possible combinations of the 20 artificial amino acids for the desired length -- say, 10 blocks long. The ribosomes then churn away, making the peptides.

To search for potential medicines, the peptide library would be mixed with a molecule of interest, say Hedgehog, a protein implicated in cancer. Peptides that bind Hedgehog would stick, and those that don’t would be washed away. Then, using a messenger RNA identifier Merryman has engineered to stay attached to each peptide, the genetic instructions for "winning" peptides can be selectively amplified. By repeatedly building the library, testing the peptides, and amplifying the winning ones, the library "evolves," gradually accumulating the most promising peptides.


The research was funded by the National Institutes of Health and the Howard Hughes Medical Institute.

Joanna Downer | EurekAlert!
Further information:
http://www.hopkinsmedicine.org/
http://www.chembiol.com/content/article/abstract?uid=PIIS1074552104000857

More articles from Life Sciences:

nachricht New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>