Featured Research

from universities, journals, and other organizations

Positioning enzymes with ease

Date:
April 11, 2011
Source:
Arizona State University
Summary:
Scientists have developed a superior method for immobilizing enzymes on surfaces, deftly controlling their orientation, improving their efficiency and rendering them more stable.

Peptide chains composed of 20 amino acids (blue) hold an enzyme in its proper orientation on a glass slide, permitting high-efficiency catalysis.
Credit: Image courtesy of Arizona State University

Virtually all processes in the human body rely on a unique class of proteins known as enzymes. To study them, scientists want to attach these molecules to surfaces and hold them fast, but this can often be a tricky undertaking.

Related Articles


Now Jinglin Fu and his colleagues at the Biodesign Institute at Arizona State University have developed a superior method for immobilizing enzymes on surfaces, deftly controlling their orientation, improving their efficiency and rendering them more stable. The group's results appear in the April 11 advanced online issue of PLoS ONE.

Enzymes are essential for the normal functioning of cells, and are involved in tasks including cell regulation, metabolism and signal transduction. They are also necessary for muscle contraction and the transport of ions and other materials throughout the cytoskeleton.

Enzymes like amylases and proteases are central players in the digestive systems of many animals, breaking down starches and other large molecules into smaller parts that can be absorbed by the intestines. Herbivorous animals make use of the enzyme cellulose, to break down plant fiber. "No wonder enzyme function has been a topic of longstanding concern for biochemistry and medicine," says Fu.

Like other proteins, enzymes are composed of linear chains of amino acids. They can range from tens to thousands of amino acids in length. The job of the enzyme is to increase the rate of the desired reaction, without increasing the rate of undesired reactions. Here, a molecule known as the substrate interacts with a given enzyme to produce a product. Without enzymes, many reactions essential to living things could not proceed.

Such catalytic activity has also been adapted and broadly applied in the biomedical arena (especially for various diagnostic testing), as well for industrial applications ranging from photography to the brewing of beer.

Enzymes are also critical for the study of disease. Given their central role in maintaining homeostasis, any single enzyme aberration, including mutation, overproduction, underproduction or deletion can have dire consequences for health. Phenylketonuria, for example, is a disease linked with a single amino acid mutation in the enzyme phenylalanine hydroxylase. If untreated, the condition can lead to mental retardation. Malfunctioning of DNA repair enzymes is associated with a number of forms of cancer.

To properly study enzymes, particularly their catalytic activity, it is necessary to fix them in place on a surface. While researchers have used several techniques for enzyme immobilization, existing methods suffer from several shortcomings. Enzymes need to be properly oriented on the surface with respect to the molecule they are catalyzing in order to work properly. The non-specific binding of proteins can contaminate the reaction and lower or block its efficient progress. Finally, proteins are prone to becoming unfolded and deactivated over time -- a process known as denaturation.

In the current study, Fu first generated a high-density array of peptides on a glass slide, each peptide composed of 20 randomly assembled amino acids. A specific enzyme, β galactosidase, was then screened against this array. This method identified two peptides that covalently bound to the enzyme with high affinity, and these were used for the subsequent experiments.

When compared with low-affinity binding peptides and with preexisting surface immobilization techniques, the group found that the high affinity peptides not only were more effective at holding the enzyme in its proper orientation on the slide, they also produced higher specific activity in the enzyme. The enzyme was also less subject to denaturation, compared with controls.

In a further refinement of the technique, the group created mutations of the high affinity peptides, by deleting a single amino acid along the peptide's length and replacing it with a different amino acid. This procedure was repeated with all 20 amino acids in the peptide chain, with the resulting mutations once more screened against the β galactosidase enzyme. The technique, known as single-point variant screening, improved both the binding affinity and specific activity of the bound enzyme.

"This development gives us a new tool, both for enhancing the function of surface bound enzymes, which are of ever-increasing importance to industry, and also for studying the interactions between multiple enzymes in a metabolic pathway," said Neal Woodburry, a co-author of the PLoS ONE study.


Story Source:

The above story is based on materials provided by Arizona State University. The original article was written by Richard Harth. Note: Materials may be edited for content and length.


Cite This Page:

Arizona State University. "Positioning enzymes with ease." ScienceDaily. ScienceDaily, 11 April 2011. <www.sciencedaily.com/releases/2011/04/110411092752.htm>.
Arizona State University. (2011, April 11). Positioning enzymes with ease. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2011/04/110411092752.htm
Arizona State University. "Positioning enzymes with ease." ScienceDaily. www.sciencedaily.com/releases/2011/04/110411092752.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Kids Die While Under Protective Services

Kids Die While Under Protective Services

AP (Dec. 18, 2014) As part of a six-month investigation of child maltreatment deaths, the AP found that hundreds of deaths from horrific abuse and neglect could have been prevented. AP's Haven Daley reports. (Dec. 18) Video provided by AP
Powered by NewsLook.com
When You Lose Weight, This Is Where The Fat Goes

When You Lose Weight, This Is Where The Fat Goes

Newsy (Dec. 17, 2014) Can fat disappear into thin air? New research finds that during weight loss, over 80 percent of a person's fat molecules escape through the lungs. Video provided by Newsy
Powered by NewsLook.com
The Hottest Food Trends for 2015

The Hottest Food Trends for 2015

Buzz60 (Dec. 17, 2014) Urbanspoon predicts whicg food trends will dominate the culinary scene in 2015. Mara Montalbano (@maramontalbano) has the story. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins