was also used to catalyse the model aldol reaction, and only a low
yield of 11% was obtained with78:22 dr and 86% ee (Table 1,
entry 12). Meanwhile, to exclude the effect of Cu2+
on the
reaction, Cu2+
alone was used to catalyse the model aldol reaction,
and only a trace amount of product was observed on TLC
(Table 1, entry 13), proving that Cu2+
did not catalyse this
transformation. The above control experiments showed that high
temperature and metal ion Cu2+
, as deactivation factors of
enzyme, could greatly decrease the catalytic ability of the crude
earthworm extract on the model aldol reaction. Thus, it can be
inferred that the enzyme(s) in the crude earthworm extract
catalysed the aldol reaction.