PDH Enzyme (image) University of Wisconsin-Madison Share Print E-Mail Caption This is a three-dimensional structure of the PDH enzyme from soybean, a legume. This structure helped show that only one mutation allowed legumes to evolve a new way to make the amino acid tyrosine. Credit Craig Schenck Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.