Engaging an Undergraduate Researcher to Develop a Mushroom Tyrosinase Assay as a Summative Assessment Device for an Upper‐level Biochemistry Laboratory Course

Abstract

Working with an undergraduate enrolled in 2‐credits of independent research a mushroom tyrosinase enzyme assay was researched, piloted, and optimized during the fall 2021 semester. The assay included crude mushroom extract from Agaricus bisporus, commonly known as white button mushrooms mixed with l‐3,4 dihydroxyphenylalanine (l‐DOPA) as a substrate. Change in absorbance was measured at 475 nm in a spectrophotometer. A version of this assay was then used to write and administer a summative assessment (a lab practical) in three sections of a 6‐credit capstone laboratory course for biochemistry majors. The practical evaluated students’ ability to measure enzyme reaction rates, make accurate dilutions, apply knowledge of Michaelis‐Menten kinetics to determine the Km and the Vmax of an enzyme of which they had little or no prior knowledge, and finally to gauge ability to determine the inhibition constant (Ki) of a provided inhibitor (kojic acid). While researching and optimizing this assay the undergraduate researcher gained hands‐on experience troubleshooting, preparing stock buffer solutions, realizing the limitations of certain substrate solubility, and observing the time constraints of an assay in which measurable products autocatalyze to form products that are not measurable by a spectrophotometer. The development of this assay and practical exam were both extremely student‐centered as the student gained practice judging the quality and feasibility of assays by searching and reading biochemistry and molecular biology education literature and communicating both via email and in‐person with corresponding authors. Generating new course content in a large lab courses with multiple sections is a challenge, especially in courses that have been taught for many years. Providing search parameters to an independent undergraduate researcher and suggesting journals to begin looking for feasible published protocols led to the implementation of an assay that piqued the interest of the student and lab instructors while also being useful as a tool for biochemistry laboratory assessment.