different rates according to their structure and electrical charge. This results in separation that enables the biochemist to isolate a relatively pure sample of an individual protein in the mixture. Scientists use specialized marker substances that attach to molecules and make it possible to follow their movement in a solution and to determine which ones move faster than others. The result is called an electrophoretic pattern. These patterns have been determined for many biological substances and can serve as a way to identify proteins.
Working with egg albumin, which was known to be a phosphoruscontaining protein, or phosphoprotein (a class that researchers found interesting but where little work had been done), Perlmann monitored patterns that were evident through electrophoretic analysis. She discovered that some enzymes called phosphatases could remove the phosphate from the ovalbumin protein. She reported that three native forms of ovalbumin exist with one, two, or no phosphate groups.
Making use of similar studies to monitor phosphate attachment and removal, Perlmann did her most significant work on pepsin and its inactive precursor protein, pepsinogen. Pepsin plays an important role in the human digestive process. It is secreted in the form of pepsinogen by cells in the stomach known as chief cells. Digestion breaks down food proteins, liberating the amino acids that form them. The process begins in the stomach where there exists an acidic environment, a condition required to initiate pepsinogen's chemical transformation into pepsin. Digestion of protein into amino acids occurs in the duodenum, a portion of the small intestine. Once the proteins are broken down, their component amino acids are absorbed and distributed among tissues in the body to form amino acid source pools available for protein synthesis as needed by various organs.
Perlmann performed amino acid analysis of pepsin and determined the sequence of amino acids that forms the segment of pepsinogen that comes off the molecule when it changes into pepsin. Optical studies enabled her to determine the three-dimensional structures of pepsin and pepsinogen. She measured the effects of changing chemical conditions and temperature to demonstrate the distinct means by which the proteins maintain their structure.
Perlmann won the American Chemical Society's Garvan Medal in 1965, which honors distinguished service to chemistry by women. She died in New York City in 1974.
"Garvan Medal." Chemical and Engineering News 43, no. 15 ( April 12, 1965): 94. McGraw-Hill Modern Scientists and Engineers 2 ( 1980): 409-410. Perlmann Gertrude E. "Correlation between Optical Rotation, Fluorescence, and"Biological Activity of Pepsinogen."