Kinases general definition

The catalytic center is formed by residues from both lobes. Sequence comparisons, mutation experiments and biochemical studies indicate an essential fimction in catalysis of phosphate transfer for the conserved amino acids Lys72, Aspl66 and Aspl84 (numbering of PKA). However, the catalytic mechanism of phosphate transfer is not definitely established. It is generally assumed that Aspl66, which is invariant in all protein kinases, serves as a catalytic base for activation of the Ser/Thr hydroxyl and that the reaction takes place by an in-line attack of the Ser-OH at the y-phosphate. 

Biosensor instruments such as Biacore (General Electric) exploit the sensitivity of a surface plasmon resonance response to the mass localised near the surface of a sensor chip. Various approaches can be used for kinases. Inhibition in solution assays involve immobilisation of a target definition compound (TDQ on the sensor surface.13,30 A buffer containing the kinase is flowed over the surface so that the protein is able to bind to the immobilised TDC, giving a signal. When test compounds are included in the buffer, they can compete for the TDC-kinase interaction, allowing estimation of Kd. 

---