Introduction

Negatively stained catalase crystals were used as a test specimen to automate the transmission electron microscope (TEM). Catalase was chosen as the specimen for automation because the crystals are rectangular and can be modeled for recognition by the automation software, and because the quality of the specimen can be assessed from the diffraction pattern of the crystals.

Catalase is an enzyme found in every cell and is especially abundant in the liver where it oxidizes toxic compounds. It has long been used in electron microscopic studies of protein structure due to its ability to form 2-dimensional crystals. In addition, acquiring quality images of catalase is often used as a test for students taking a course in electron microscopy. These practical and historical considerations make catalase crystals an excellent choice for developing research methods to solve the general problems of automated image acquisition.

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