Enzyme Cofactors:
A co factor is a non protein chemical compound that is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations Enzyme function is often assisted by additional chemical components known as cofactors. For example, the active sites of many enzymes contain metal ions that help draw electrons away from substrate molecules. The enzyme carboxypeptidase digests proteins by employing a zinc ion (Zn++) in its active site to remove electrons from the bonds joining amino acids. Other elements, such as molybdenum and manganese, are also used as cofactors. Like zinc, these substances are required in the diet in small amounts. When the cofactor is a nonprotein organic molecule, it is called a coenzyme. Many vitamins are parts of coenzymes. In numerous oxidation-reduction reactions that are catalyzed by enzymes, the electrons pass in pairs from the active site of the enzyme to a coenzyme that serves as the electron acceptor. The coenzyme then transfers the electrons to a different enzyme, which releases them (and the energy they bear) to the substrates in another reaction. Often, the electrons pair with protons (H+) as hydrogen atoms.
In this way, coenzymes shuttle energy in the form of hydrogen atoms from one enzyme to another in a cell.
Some enzymes or enzyme complexes require several cofactors. For example, the multienzyme complex pyruvate dehydrogenase at the junction of glycolysis and the citric acid cycle requires five organic cofactors and one metal ion: loosely bound thiamine pyrophosphate (TPP), covalently bound lipoamide and flavin adenine dinucleotide (FAD), and the cosubstrates nicotinamide adenine dinucleotide (NAD+) and coenzyme A (CoA), and a metal ion (Mg2+). Organic cofactors are often vitamins or are made from vitamins. Many contain the nucleotide adenosine monophosphate (AMP) as part of their structures, such as ATP, coenzyme A, FAD, and NAD+. This common structure may reflect a common evolutionary origin as part of ribozymes in an ancient RNA world. It has been suggested that the AMP part of the molecule can be considered a kind of "handle" by which the enzyme can "grasp" the coenzyme to switch it between different catalytic centers. One of the most important coenzymes is the hydrogen acceptor nicotinamide adenine dinucleotide (NAD+)as shown in the figure below. The NAD+ molecule is composed of two nucleotides bound together.A nucleotide is a five-carbon sugar with one or more phosphate groups attached to one end and an organic base attached to the other end. The two nucleotides that make up NAD+, nicotinamide monophosphate (NMP) and adenine monophosphate (AMP), are joined head-to-head by their phosphate groups. The two nucleotides serve different functions in the NAD+ molecule: AMP acts as the core, providing a shape recognized by many enzymes; NMP is the active part of the molecule, contributing a site that is readily reduced (that is, easily accepts electrons). When NAD+ acquires an electron and a hydrogen atom (actually, two electrons and a proton) from the active site of an enzyme, it is reduced to NADH. The NADH molecule now carries the two energetic electrons and the proton. The oxidation of energy-containing molecules, which provides energy to cells, involves stripping electrons from those molecules and donating them to NAD+. As we’ll see, much of the energy of NADH is transferred to another molecule. Enzymes have an optimum temperature and pH, at which the enzyme functions most effectively. Inhibitors decrease enzyme activity, while activators increase it. The activity of enzymes is often facilitated by cofactors, which can be metal ions or other substances. Cofactors that are non-protein organic molecules are called coenzymes.
How enzymes can be inhibited. (a) In competitive inhibition, theinhibitor interferes with the active site of the enzyme. (b) Innoncompetitive inhibition, the inhibitor binds to the enzyme at aplace away from the active site, effecting a conformational change in the enzyme so that it can no longer bind to its substrate.
The chemical structure of nicotinamide adenine dinucleotide
(NAD+). This key cofactor is composed of two nucleotides, NMP and AMP, attached head-to-head.
Thus Enzymes and Inhibitors can play major role in effectiveness of any drug and and its action on the target .Thus drug manufacturers always consider about the element mainly transition elements like molybdenum,cobalt,iron,zinc,titanium,copper ..as active site of enzymes and their fit to the substrate for its effective action.
A co factor is a non protein chemical compound that is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations Enzyme function is often assisted by additional chemical components known as cofactors. For example, the active sites of many enzymes contain metal ions that help draw electrons away from substrate molecules. The enzyme carboxypeptidase digests proteins by employing a zinc ion (Zn++) in its active site to remove electrons from the bonds joining amino acids. Other elements, such as molybdenum and manganese, are also used as cofactors. Like zinc, these substances are required in the diet in small amounts. When the cofactor is a nonprotein organic molecule, it is called a coenzyme. Many vitamins are parts of coenzymes. In numerous oxidation-reduction reactions that are catalyzed by enzymes, the electrons pass in pairs from the active site of the enzyme to a coenzyme that serves as the electron acceptor. The coenzyme then transfers the electrons to a different enzyme, which releases them (and the energy they bear) to the substrates in another reaction. Often, the electrons pair with protons (H+) as hydrogen atoms.
In this way, coenzymes shuttle energy in the form of hydrogen atoms from one enzyme to another in a cell.
Some enzymes or enzyme complexes require several cofactors. For example, the multienzyme complex pyruvate dehydrogenase at the junction of glycolysis and the citric acid cycle requires five organic cofactors and one metal ion: loosely bound thiamine pyrophosphate (TPP), covalently bound lipoamide and flavin adenine dinucleotide (FAD), and the cosubstrates nicotinamide adenine dinucleotide (NAD+) and coenzyme A (CoA), and a metal ion (Mg2+). Organic cofactors are often vitamins or are made from vitamins. Many contain the nucleotide adenosine monophosphate (AMP) as part of their structures, such as ATP, coenzyme A, FAD, and NAD+. This common structure may reflect a common evolutionary origin as part of ribozymes in an ancient RNA world. It has been suggested that the AMP part of the molecule can be considered a kind of "handle" by which the enzyme can "grasp" the coenzyme to switch it between different catalytic centers. One of the most important coenzymes is the hydrogen acceptor nicotinamide adenine dinucleotide (NAD+)as shown in the figure below. The NAD+ molecule is composed of two nucleotides bound together.A nucleotide is a five-carbon sugar with one or more phosphate groups attached to one end and an organic base attached to the other end. The two nucleotides that make up NAD+, nicotinamide monophosphate (NMP) and adenine monophosphate (AMP), are joined head-to-head by their phosphate groups. The two nucleotides serve different functions in the NAD+ molecule: AMP acts as the core, providing a shape recognized by many enzymes; NMP is the active part of the molecule, contributing a site that is readily reduced (that is, easily accepts electrons). When NAD+ acquires an electron and a hydrogen atom (actually, two electrons and a proton) from the active site of an enzyme, it is reduced to NADH. The NADH molecule now carries the two energetic electrons and the proton. The oxidation of energy-containing molecules, which provides energy to cells, involves stripping electrons from those molecules and donating them to NAD+. As we’ll see, much of the energy of NADH is transferred to another molecule. Enzymes have an optimum temperature and pH, at which the enzyme functions most effectively. Inhibitors decrease enzyme activity, while activators increase it. The activity of enzymes is often facilitated by cofactors, which can be metal ions or other substances. Cofactors that are non-protein organic molecules are called coenzymes.
How enzymes can be inhibited. (a) In competitive inhibition, theinhibitor interferes with the active site of the enzyme. (b) Innoncompetitive inhibition, the inhibitor binds to the enzyme at aplace away from the active site, effecting a conformational change in the enzyme so that it can no longer bind to its substrate.
The chemical structure of nicotinamide adenine dinucleotide
(NAD+). This key cofactor is composed of two nucleotides, NMP and AMP, attached head-to-head.
Thus Enzymes and Inhibitors can play major role in effectiveness of any drug and and its action on the target .Thus drug manufacturers always consider about the element mainly transition elements like molybdenum,cobalt,iron,zinc,titanium,copper ..as active site of enzymes and their fit to the substrate for its effective action.
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— Abraham Malik (@brhmmlk93_malik) March 23, 2015http://advancedmathematicalresearch.blogspot.in/
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