Studies on auxin protectors. XII. Auxin protectors and polyphenol oxidase in developing coffee fruit

The fruit of the coffee plant (Coffea arabica) was analyzed for auxin protector content. Ripe coffee berries were separated into pit and pulp, ground in buffer, and assayed for auxin protectors. The extracts were then subjected to gel filtration in order to determine the molecular weight of the protector(s). In the pit, a single protector was found with a molecular weight approaching 5000 daltons, while the pulp contained several auxin protectors, the largest of which appeared to be about 1000 daltons. Chromato-graphic studies of various gel filtration fractions showed that protector activity was always associated with spots which exhibited a light blue fluorescence under UV. The changing patterns during coffee fruit development were also investigated. Auxin protector production, and polyphenol oxidase (E.C. 1.10.3.1), an enzyme related to protector metabolism, were assayed at weekly intervals. In the unripe berry, an auxin protector was found with a molecular weight exceeding 200,000 daltons; as the berry ripened the amount of this protector gradually decreased until almost none was present in the ripe berry and the pattern changed to the pattern described above. Polyphenol oxidase content decreased as the berry ripened. Commercially roasted pits, i.e., coffee “beans”, contained very high levels of protector activity. However, gel filtration studies showed this activity to be associated entirely with low molecular weight compounds.