Previous studies have utilized activated mutant variants of non-receptor tyrosine kinases like SRC to identify downstream substrates of this kinase subfamily; however, these overexpressed, constitutively active mutants likely display promiscuous activities that do not necessarily reflect the substrates of the endogenous protein when activated by an upstream RTK.
In contrast, chimeric enzymes previously constructed by homology-independent recombination of hGSTT-1 and rGSTT2-2 exhibited very different substrate promiscuity profiles, and showed a more defined relationship between evolved and promiscuous activities.
Many enzymes possess, besides their native function, additional promiscuous activities.
In addition to catalyzing acyl transfer reactions, a number of promiscuous activities have been described recently.
Recent work suggests that the universe of promiscuous activities available in nature is enormous.
There is a growing consensus that many enzymes mediate undocumented side-reactions (known as promiscuous activities) as a result of exposure to diverse cellular metabolites [16, 17].
Our results show that new enzymatic functions could evolve rapidly from the current diversity of enzymes and range of promiscuous activities.
Promiscuous activities can provide the starting point for evolution of new enzymes, both in nature and in the hands of protein engineers.
Besides such sources of uncertainty in samples, many unassigned peaks should also be due to promiscuous activities of enzymes not yet characterized because of the lack of an appropriate description of the mechanisms of enzyme promiscuity.
New high-throughput approaches have significantly advanced our ability to identify promiscuous activities, setting the stage for synthetic biology efforts to construct novel pathways using catalysts derived from promiscuous enzymes via directed evolution.
The design space for these tests is limited by a variety of possible background reactions, which often originate from relatively weak promiscuous activities of the enzymes used for nucleic acid amplification.
