PNMT Human
Description
PNMT is purified by conventional chromatographic techniques.
Product Specs
Product Science Overview
Phenylethanolamine-N-Methyltransferase (PNMT) is an enzyme that plays a crucial role in the biosynthesis of catecholamines. It is primarily found in the adrenal medulla, where it catalyzes the conversion of norepinephrine (noradrenaline) to epinephrine (adrenaline) . This enzyme is also expressed in small groups of neurons in the human brain and in selected populations of cardiomyocytes .
PNMT is encoded by a gene located on chromosome 17 in humans . The enzyme consists of 282 amino acids and has a molecular weight of approximately 30 kDa . The structure of PNMT includes several key features that are essential for its function. The active site of the enzyme contains aromatic residues such as phenylalanine and tyrosine, which help stabilize the binding of the cofactor S-adenosyl-L-methionine (SAM) through pi stacking . Additionally, the residue Glutamine 185 is necessary for binding the catecholamine substrate .
PNMT catalyzes the transfer of a methyl group from SAM to norepinephrine, converting it into epinephrine . The enzyme works by bringing the cofactor SAM and the substrate norepinephrine into close proximity, allowing the reactive methyl group to be transferred to the primary amine of the norepinephrine molecule . This methylation process is crucial for the production of epinephrine, which plays a vital role in the body’s response to stress and in the regulation of various physiological functions.
Recombinant human PNMT has been successfully produced in Escherichia coli . The gene encoding PNMT was amplified from a human adrenal medulla cDNA library and ligated into an expression vector . The enzyme was then expressed in E. coli, yielding about 10% of the soluble protein . The recombinant enzyme was purified to homogeneity using ammonium sulfate fractionation, ion-exchange chromatography, and gel filtration . The kinetic parameters of the recombinant enzyme, such as the Km values for phenylethanolamine and SAM, were determined to be 130 and 16 micromolar, respectively .
PNMT is highly expressed in adrenal medullary chromaffin cells and is also present in neurons in the medulla oblongata, the hypothalamus, and sensory nuclei of the vagus nerve . The enzyme’s activity can be influenced by various genetic and environmental factors, making it a subject of interest in pharmacogenomics . Understanding the genetic variations and regulatory mechanisms of PNMT can provide insights into the development of therapeutic strategies for conditions related to catecholamine imbalances, such as hypertension and heart disease.
