Plant Physiology - Musiyenko M. M. 2001

General principles of plant growth and morphogenesis regulation
Metabolic regulation

Metabolic Regulation is achieved primarily by controlling The activity of various Enzymes, specifically through their isosteric and Allosteric Regulation. Isosteric regulation takes place at the catalytic centers of enzymes by altering the physicochemical environmental conditions (pH, ionic surrounding, concentration of substrates and reaction products) in which they operate. A more advanced METABOLISM/10.html">Mechanism of enzyme activity control is allosteric regulation. Enzymes with this type of regulation feature a regulatory protein subunit capable of interacting with specific activators or inhibitors (effectors). These effectors can be certain metabolites, Hormones, other physiologically active substances, or even the substrate molecules themselves. The interaction between effectors and the regulatory subunit alters its conformation, which in turn cooperatively affects the functional activity of the enzyme's catalytic subunit.

Enzyme activity is also regulated through modification via phosphorylation, Acetylation, methylation, Cleavage of disulfide Bonds, etc. Specific inhibitors can block enzyme action. Enzyme activity can likewise decrease due to its binding by membrane complexes.

Another fairly common pathway of enzymatic regulation is the Transformation of a latent enzyme form into an active form. This occurs, for example, during the cleavage of covalent bonds involving proteases, the reduction of disulfide groups, or the association of inactive enzyme subunits, among other mechanisms.

Metabolic cycles regulated by enzymes through feedback and feedforward loops constitute the core of metabolic regulation.