Increase in enzyme activity - (Jul/16/2014 )

It is usually a trend to see a decline in enzyme activity as time passes but  I am seeing an increase in enzyme activity after a period of incubation/storage (after the partial purification). Are there any comments about this scenario?

since it's only partially purified there are a few possible reasons why enzyme activity may increase. here are a few which immediately come to mind:

partial hydrolysis of the enzyme (may deactivate regulatory subunit or portion of the enzyme or free the active site)

conformational changes to the enzyme

decomposition of endogenous inhibitor(s)

partial aggregation sometimes increases activity (before more complete aggregation reduces activity)