Proteins are the builders and many of the building blocks of all living things. The building plan comes from DNA as conveyed by RNA, but the work and the edifice we call living tissue is the result of proteins. There are over 20,000 proteins in the human body, and they lie at the heart of some of the most important questions in biology. Pointing this out is preface to saying that a new technique for identifying proteins can be extremely important. In this case, the new technique is based on a technique that’s been around since the 1970’s but combined for the first time with a technique used in DNA analysis called the micro-array. The result is not only faster analysis of proteins, but a whole new view on their activity.

The name of the new technique looks a bit strange – the micro western blot array. The western blot is a protein analysis technique, the “blot” being a blot (drop) of protein for analysis and the “western”…well, it’s wordplay. An important DNA analysis is done with a Southern blot, named after an actual scientist, Edwin Southern. Hence, western blot…and yes, there is a northern blot (for RNA detection) and an eastern blot (also for protein). The “array” part of the name comes from the grouping of blots, which has been limited. It’s the “micro” that makes the difference here, but more on that in a bit.

First, here’s a simplified description of the western blot technique. Consider how many steps and how much time this will take: A western blot, also called a protein immunoblot, is a laboratory technique – a method – used to detect specific proteins. It starts by mixing the sample, some kind of tissue or homogenized (‘puréed’) organic material that presumably contains the target protein, into a polymer gel. The gel is subjected to electrophoresis, a process where an electric current is used to generate an electric field as Electromotive Force (EMF) to push the protein molecules in the gel at different rates depending on their mass. This process separates the types of proteins. The separated proteins are transferred to a membrane, where they are probed with antibodies specific to the target protein. The effect of the antibody reactant can be visualized with stains, fluorescence, or radioactivity, which usually leads to identification of the protein, if it is present.

Got all that? Of course, the point is that the western blot technique, like many in organic chemistry, is lengthy and often expensive. In this case, the antibody reagents can be very expensive. You may also have noticed that some educated guesswork may be involved in matching antibody for the protein (unless a fully negative – no protein found – result is desired). This process requires expertise, as well as patience and attention to detail.

The new technique, developed at the University of Chicago (USA), combines the micro-array technology used for DNA analysis, which can literally process thousands of genes at single go, with the western blot for proteins. Now instead of identifying 1, 2, or 5 proteins at a time, the micro western array can compare hundreds of proteins simultaneously. It also needs far smaller samples and just nanoliters of antibodies. (It can save big money.) However, the signal accomplishment goes beyond economy and efficiency; for the first time biologists can get an overview of protein activity from a single procedure. It’s like going from a snapshot with a couple of spots of light in mostly darkness, to a snapshot with at least an outline of what’s in the picture.

“The proteins are the actual machines that are doing everything in the cell, but nobody’s been able to examine them in depth because it’s been too complicated. Now, we can begin to do that with this new method,” said Richard B. Jones, senior author and assistant professor at and the University of Chicago’s Ben May Department for Cancer Research and the Institute for Genomics and Systems Biology.
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“In the clinic, you’re limited by the fact that typically most cancers are diagnosed by one or two markers; you’re looking for one or two markers that are high or low then trying to diagnose and treat an illness,” Jones said. “Here, we can potentially measure a collection of proteins at the same time and not just focus on one guess. We’ve never been able do that before.”

Other scientists in the field of systems biology said that micro-western arrays would make possible experiments that were previously beyond the scope of laboratory methods.

[Source: EurekAlert]