Related Experiment Video
Updated: Jul 31, 2026
13:22
Kinase Inhibitor Screening In Self-assembled Human Protein Microarrays
Published on: October 23, 2019
Target enzymes for plasma proteinase inhibitors
Folia Histochemica Et Cytobiologica
|January 1, 1986
Summary
Plasma inhibitors rapidly control tissue proteolytic activity by inactivating specific proteinases. These inhibitors act as substrates, trapping enzymes in complexes for efficient regulation.
Area of Science:
- Biochemistry
- Molecular Biology
- Physiology
Background:
- Proteolytic activity is crucial for physiological processes but requires tight regulation.
- Plasma inhibitors are key regulators of proteinase activity in tissues.
- Dysregulated proteolysis is implicated in various diseases.
Purpose of the Study:
- To elucidate the mechanism by which plasma inhibitors control proteolytic activity.
- To investigate the kinetics of inhibitor-proteinase interactions.
- To understand the role of inhibitors as substrates in enzyme inactivation.
Main Methods:
- Kinetic experiments were performed to analyze inhibitor-proteinase reactions.
- Studies focused on the association and dissociation rates of inhibitor-enzyme complexes.
- Inhibitor modification was used to probe the mechanism of inhibition.
Main Results:
- Plasma inhibitors rapidly inactivate specific target proteinases.
- Inhibitor-proteinase reactions are significantly faster with target enzymes compared to off-target enzymes.
- Inhibitors function as substrates, forming stable complexes with proteinases through slow dissociation.
Conclusions:
- Plasma inhibitors effectively control proteolytic activity through substrate-like interactions.
- The 'trapping' mechanism ensures rapid and specific enzyme inactivation.
- This mechanism highlights the sophisticated regulation of proteolysis in biological systems.
Related Concept Videos
01:30Enzyme Inhibition
Inhibitors are molecules that reduce enzyme activity by binding to the enzyme. In a normally functioning cell, enzymes are regulated by a variety of inhibitors. Drugs and other toxins can also inhibit enzymes. Some inhibitors bind to the enzyme’s active site, while others inhibit enzymatic activity by binding to other sites on the protein structure.
01:29Drug Distribution: Plasma Protein Binding
Drugs predominantly attach to plasma proteins, with only a small percentage remaining unbound. The unbound portion can be calculated as one minus the bound fraction. Acidic drugs form large, inactive complexes by reversibly binding to plasma albumin, which prevents them from diffusing across biological barriers. These drug-protein complexes act as reservoirs for the drugs. As the concentration of unbound drugs decreases, these complexes quickly dissociate to release the free drug, maintaining...
01:09Hepatic Drug Clearance: Effect of Protein Binding
Hepatic clearance is influenced by protein binding based on the drug's extraction ratio. Drugs with high extraction ratios are considered flow-limited and remain unaffected by protein binding during hepatic clearance. On the other hand, drugs with low extraction ratios may be impacted by plasma protein binding, although the extent of this influence depends on the fraction of the drug bound.
For low-extraction-ratio drugs that are less than 80% protein-bound, minor changes in protein binding...
For low-extraction-ratio drugs that are less than 80% protein-bound, minor changes in protein binding...
01:25Pharmacokinetics: Drug–Drug Interactions
Drug interactions occur when the pharmacological effect of one drug is altered by another substance, either enhancing or diminishing its activity. The drug whose activity is altered is known as the object drug, and the substance causing the alteration is called the agent drug or the precipitant. The net effects of these interactions are mostly undesirable, leading to decreased effectiveness or increased adverse effects. In rare cases, interactions can be beneficial, such as the enhanced...
01:28Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes
Cytochrome P450 (CYP450) enzymes are a superfamily of heme-containing monooxygenases that play a pivotal role in Phase I drug metabolism by catalyzing oxidation and reduction reactions.These enzymes transform lipophilic xenobiotics into more hydrophilic metabolites, facilitating subsequent Phase II conjugation and eventual excretion. The CYP450 family is classified into families (e.g., CYP1–CYP3) and subfamilies (e.g., CYP2A, CYP2C), based on amino acid sequence homology.CYP450 isoenzymes,...
01:27Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase
Phase II biotransformation reactions are essential for detoxifying and eliminating xenobiotics, including many pharmaceutical compounds. These reactions typically involve conjugation, the covalent attachment of polar endogenous groups such as glucuronic acid, sulfate, methyl, or acetyl moieties to functional groups introduced during Phase I metabolism. The resulting conjugates are more water-soluble, enabling efficient renal or biliary excretion.The major classes of Phase II enzymes include...