“…Similarly, steric hindrance to molecular interactions may also result from attachment of proteins onto the stationary matrix and exposure to cytosolic extracts containing metabolites [2,19,20]. To date several approaches have used these types of strategies, such as protein microarrays [2,20], small molecule arrays [7,18], surface plasmon resonance [21], and nuclear magnetic resonance [22]. These in vitro interactions can be affected by factors that include ion strength, solvent, redox, etc., which may not be physiological in vivo.…”