Biochemical reactions in cells are catalyzed by a diverse set of functional proteins called enzymes and represent the fundamental processes that control all aspects of cell behaviour and physiology. Enzymes can modulate (i.e., increase or decrease) the rates of a biochemical reaction without being altered in the process. In a biochemical reaction, the molecule at the beginning of the process is called a substrate and it is converted into a different molecule called the product.
The activity of an enzyme can be regulated by different factors. Inhibitors are molecules that decrease enzyme activity while activators are molecules that increase activity. There are many classes of enzymes in any given cell and the enzymes are usually under stringent cellular control since defects in these can have deleterious consequences for the cell. The rate and efficiency of a biochemical reaction is determined by the expression level and the activity state of the appropriate enzyme. A given enzyme can exist in both an "active" and "inactive" state as well as "high" and "low" expression levels in the cell. Depending on which stimuli (growth factors, cytokines or hormones) impacts a cell, this dictates which enzyme component will be turned "on" or "off" and what biochemical reaction will occur.
Biochemical reactions are reversible in nature and different enzymes can catalyze the forward and reverse direction of a given reaction. The ability of enzymes to catalyze a biochemical reaction is an ideal characteristic that has been extensively exploited for drug discovery efforts. Majority of the drugs discovered to date inhibit or activate a given enzyme target and this in turn ultimately determines the effect of a given drug.
There are many types of enzymes in a cell and this includes signalling enzymes (such as protein kinases, protein phosphatases, phosphodiesterases, histone deacteylases) that are involved in post translational modification of proteins and cellular metabolites; house-keeping enzymes that are involved on maintenance and survival of a cell; enzymes involved in growth, division and differentiation of a cell. SignalChem currently offers the following enzymes: active protein kinases, active protein phosphatases, active phosphodiesterases (PDE) and active histone deacetylases (HDAC).