substrate

Examples of substrate in the following topics:

• Enzyme Active Site and Substrate Specificity

  • Enzymes bind with chemical reactants called substrates.
  • In others, two substrates may come together to create one larger molecule.
  • The enzyme's active site binds to the substrate.
  • A specific chemical substrate matches this site like a jigsaw puzzle piece and makes the enzyme specific to its substrate.
  • When an enzyme binds its substrate, it forms an enzyme-substrate complex.

• Control of Metabolism Through Enzyme Regulation

  • In competitive inhibition, an inhibitor molecule is similar enough to a substrate that it can bind to the enzyme's active site to stop it from binding to the substrate.
  • It "competes" with the substrate to bind to the enzyme.
  • Their binding induces a conformational change that reduces the affinity of the enzyme's active site for its substrate. 
  • Allosteric inhibitors modify the active site of the enzyme so that substrate binding is reduced or prevented.
  • In contrast, allosteric activators modify the active site of the enzyme so that the affinity for the substrate increases.

• Types and Functions of Proteins

  • Because form determines function, each enzyme is specific to its substrates.
  • The substrates are the reactants that undergo the chemical reaction catalyzed by the enzyme.
  • When the substrate binds to its active site at the enzyme, the enzyme may help in its breakdown, rearrangement, or synthesis .
  • Anabolic enzymes: enzymes that build more complex molecules from their substrates
  • A catabolic enzyme reaction showing the substrate matching the exact shape of the active site.

• ATP in Metabolism

  • In many cellular chemical reactions, enzymes bind to several substrates or reactants to form a temporary intermediate complex that allow the substrates and reactants to more readily react with each other.
  • In reactions where ATP is involved, ATP is one of the substrates and ADP is a product.
  • During an endergonic chemical reaction, ATP forms an intermediate complex with the substrate and enzyme in the reaction.
  • This intermediate complex allows the ATP to transfer its third phosphate group, with its energy, to the substrate, a process called phosphorylation.
  • When the intermediate complex breaks apart, the energy is used to modify the substrate and convert it into a product of the reaction.

• Plasma Membrane Hormone Receptors

  • Adenylyl cyclase catalyzes the conversion of ATP to cAMP. cAMP, in turn, activates a group of proteins called protein kinases, which transfer a phosphate group from ATP to a substrate molecule in a process called phosphorylation.
  • The phosphorylation of a substrate molecule changes its structural orientation, thereby activating it.
  • The specific response of a cell to a lipid-insoluble hormone depends on the type of receptors that are present on the cell membrane and the substrate molecules present in the cell cytoplasm.

• Mosses

  • In the tundra, the mosses' shallow rhizoids allow them to fasten to a substrate without penetrating the frozen soil.
  • Additionally, mosses are anchored to the substrate, whether it is soil, rock, or roof tiles, by multicellular rhizoids.

• The Energy-Releasing Steps of Glycolysis

  • (This is an example of substrate-level phosphorylation. ) A carbonyl group on the 1,3-bisphosphoglycerate is oxidized to a carboxyl group, and 3-phosphoglycerate is formed.
  • The last step in glycolysis is catalyzed by the enzyme pyruvate kinase (the enzyme in this case is named for the reverse reaction of pyruvate's conversion into PEP) and results in the production of a second ATP molecule by substrate-level phosphorylation and the compound pyruvic acid (or its salt form, pyruvate).

• Bryophytes

  • In a bryophyte, all the conspicuous vegetative organs, including the photosynthetic leaf-like structures, the thallus, stem, and the rhizoid that anchors the plant to its substrate, belong to the haploid organism, or gametophyte.

• Metabolic Pathways

  • A metabolic pathway is a step-by-step series of interconnected biochemical reactions that convert a substrate molecule or molecules through a series of metabolic intermediates, eventually yielding a final product or products.

• Regulatory Mechanisms for Cellular Respiration

  • This alteration of the protein's (the enzyme's) structure either increases or decreases its affinity for its substrate, with the effect of increasing or decreasing the rate of the reaction.