ATP, adenosine triphosphate
, is a molecule composed of nucleotide adenine, ribose and three phosphate groups. During the hydrolysis produces vast amounts of energy due to the loss of a phosphate group making ADP, adenosindifosfato . Therefore produces a reaction exergonic.
ribozymes are RNA. A biological catalyst provides the scaffolding over which the chemical catalysis. The barrier
energentica is representing the amount of energy needed to start the reaction, defined
activation energy (Ea). Overcome the energy barrier to molecules that can undergo transformation to move into unstable states defininti transition states. Enzymes are highly specific in catalyzing reactions only for a particular type of molecule. The name of the enzyme, often ending with the suffix - asi reflects its function. The
molecules that come into contact with the enzyme substrate are called, they bind to a particular binding site of the enzyme active site that , producing an enzyme-substrate complex.
How enzymes work?
enzymes
- orient the substrate molecules in order to bind the atoms of the substrate-linked enzyme. - induce tension in the substrate molecules. - temporarily add chemical groups to the molecules of substrate - acid-base catalysis - covalent catalysis
- catalysis by metal ions
An enzyme is composed of hundreds of amino acids with possible quaternary structure. The substrate is rather a very simple molecule of 6-12 amino acids. Each active site is specific to the substrate. An enzyme then changes shape on binding to the substrate ( induced adaption), the rest of the molecule provides the scaffolding that allows the amino acids of the active site to position itself properly, change is in the shape of the molecule.
enzymes often require other molecules for catalysis:
-
prosthetic groups other than amino acid molecules
→
-
cofactors
→ inorganic ions
-
coenzymes →
carbon-containing molecules in the reaction A → B reaction rate is directly proportional to the amount of A, the more the faster the substrate is the enzyme action. Moreover, the amount of enzyme is much less than the amount of substrate, therefore, we observe the saturation
, achieving maximum speed. The turnover is a measure of the amount of enzyme molecules converted per unit time.
How are enzymes regulated? L '
homeostasis is the stability condition of the bodies, each body has a number of reactions that quantifies the number of items inside. The biology system is responsible for defining and studiarte the
pathways, ie the path that a molecule makes to the transformation in essential elements. Each reaction of a metabolic pathway is catalyzed by a specific enzyme. The flow of the pathway to maintain homeostasis is regulated by activators and inhibitors enzymes.
Inhibition can be - irreversible → when a molecule binds permanently with the enzyme (nerve gas) -
reversible
→ remain bound to the active site are called competitive inhibitors , those that do not bind to the active site are called non-competitive inhibitors and induce a change in shape, said allosteric
. When the enzyme is in an active form accepts the substrate, if it is inactive does not accept it.
non-competitive inhibitors and activators generally have a particular seat nell'enzima. Enzymes with the possibility of allosteric regulation
have a quaternary structure and the subunits with the active site, and work catalytic subunit, while that for activators / inhibitors (allosteric site) regulatory subunit. allosteric enzymes with capacity and are often found in the first stage of the reaction pathway that specific and limiting . This mechanism is called feedback inhibition
. enzymes are affected by characteristics ambiantali, each works best at a pH and temperature. If a body were to live in very different environments we are witnessing the emergence of isoenzymes enzymes that are of a certain pathway structure appropriate to the environment.
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