Biochemical Aspects of Enzyme Inhibition

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Questions and Answers

Which type of amino acid is arginine classified as?

Semi-essential (correct)

Tertiary

Essential

Non-essential

What is the correct classification of a peptide consisting of three amino acids?

Polypeptide

Tripeptide (correct)

Oligopeptide

Dipeptide

Which amino acid serves as the amino (N) terminal in the given peptide Val–Cys–Asp–Leu–Ala–Arg–Phe–Glu–Trp?

Cys

Leu

Trp

Val (correct)

Which of the following carbohydrate types is classified as a homopolysaccharide?

Starch Signup and view all the answers

Which amino acid is identified as the carboxyl (C) terminal in the peptide chain Val–Cys–Asp–Leu–Ala–Arg–Phe–Glu–Trp?

Trp Signup and view all the answers

What is a primary consequence of protein energy malnutrition due to lack of essential dietary requirements?

Muscle atrophy Signup and view all the answers

Which mechanism describes how heat stroke can lead to brain damage?

Denaturation of proteins in sensitive tissues Signup and view all the answers

What role does lowering body temperature play in organ cryopreservation?

Minimizes tissue damage by slowing metabolic processes Signup and view all the answers

How does penicillin affect bacterial cells?

It irreversibly inhibits transpeptidase Signup and view all the answers

What is the consequence of inappropriate activation of digestive enzymes in the pancreas?

Digestive enzymes attacking pancreatic tissue Signup and view all the answers

What is the impact of organophosphorus compounds on the nervous system?

Inhibit acetylcholine breakdown Signup and view all the answers

How does carbon monoxide affect cellular respiration?

Binds to cytochrome c oxidase Signup and view all the answers

What is the role of glutathione in the body?

Antioxidant Signup and view all the answers

What does a low Km value indicate about an enzyme's affinity for its substrate?

High affinity Signup and view all the answers

Which of the following factors does NOT affect enzyme activity?

Sodium concentration Signup and view all the answers

What effect does bradykinin have on blood pressure?

Decreases blood pressure Signup and view all the answers

Which mechanism leads to proto-oncogene activation through gene amplification?

Overproduction of the gene Signup and view all the answers

What is the effect of marked changes in pH on enzyme activity?

Denatures the enzyme Signup and view all the answers

Which of the following correctly describes the relationship between Km and Vmax?

Km is independent of Vmax Signup and view all the answers

How does vasopressin affect blood pressure?

Raises blood pressure via fluid retention Signup and view all the answers

The optimum pH range for most enzymes falls between which values?

5-9 Signup and view all the answers

Which amino acids are classified as polar uncharged?

Serine and Threonine Signup and view all the answers

What role do chaperones play in protein folding?

They assist in the proper folding of proteins. Signup and view all the answers

Which amino acids are considered essential and must be supplied in the diet?

Threonine and Methionine Signup and view all the answers

Which group of amino acids contain sulfur in their side chains?

Cysteine and Methionine Signup and view all the answers

How are ionic bonds formed in proteins?

Between positively and negatively charged amino acids Signup and view all the answers

Which amino acid is classified as an imino acid?

Proline Signup and view all the answers

Which enzyme is primarily associated with liver function and is important for diagnosing liver diseases?

Gamma-Glutamyl Transferase (GGT) Signup and view all the answers

What type of amino acid has side chains that cannot react with water?

Non-polar amino acids Signup and view all the answers

What distinguishes isoenzymes from each other?

They differ in amino acid sequence and tissue distribution. Signup and view all the answers

Which amino acid is involved in the formation of covalent disulfide bonds?

Cysteine Signup and view all the answers

What is the role of streptokinase in medical treatment?

To dissolve blood clots in myocardial infarction. Signup and view all the answers

What characteristic do aromatic amino acids share?

They absorb UV light at 280 nm Signup and view all the answers

Which of the following enzymes is associated with muscle damage?

Creatine Kinase (CK) Signup and view all the answers

Which type of amino acids are found on the surface of proteins and can react with water?

Polar charged amino acids Signup and view all the answers

Which enzyme is used therapeutically for patients with acute lymphoblastic leukemia?

Asparaginase Signup and view all the answers

Which enzyme can indicate both heart attacks and liver diseases?

Aspartate Aminotransferase (AST) Signup and view all the answers

Which isoenzyme is not associated with the brain?

Creatine Kinase (CK3) Signup and view all the answers

What is the primary substrate that asparaginase acts upon?

Asparagine Signup and view all the answers

Which enzyme is most commonly used to assess pancreatic disorders?

Amylase Signup and view all the answers

Which factor does NOT typically influence the optimal conditions of isoenzymes?

Hormone level Signup and view all the answers

Study Notes

Biochemical Aspects - Question 1 Comparison

Reversible - Competitive Inhibition: Inhibitor structure similar to substrate, binds to active site. E+I <-> EI. Km is increased, Vmax is not affected. Lineweaver-Burk plot: same y-intercept, x-intercept shifts left. Reversal by increasing substrate concentration. Examples include sulfonamides and methotrexate.
Reversible - Non-competitive Inhibition: Inhibitor structure not similar to substrate, binds to allosteric site. E+I <-> EI, ES+I <-> ESI. Vmax is decreased, Km is not affected. Lineweaver-Burk plot: same x-intercept, y-intercept shifts up. Reversal not by increasing substrate concentration, possibly by dialysis. Examples include dicumarol.

Michaelis-Menten Kinetics and Lineweaver-Burk Plots

Michaelis-Menten kinetics describes enzyme-catalyzed reactions.
Lineweaver-Burk plots are graphical representations of Michaelis-Menten data.
The Lineweaver-Burk plot uses the reciprocal of the reaction rates.
The y-intercept of the Lineweaver-Burk plot is 1/Vmax.
The x-intercept of the Lineweaver-Burk plot is -1/Km.
Competitive and non-competitive inhibitors shift the x and or y-intercepts of the lineweaver-burk plot differently

Other Concepts

Absolute Enzyme Specificity: Enzymes act on a single substrate. Example: glucokinase acts only on glucose, urease acts only on urea.
Relative Enzyme Specificity: Enzymes act on structurally similar substrates but not limited to one. Example: hexokinase acts on hexoses including glucose, fructose, mannose
Functional Plasma Enzymes: Enzymes in the blood with known functions, often synthesized by the liver to maintain health. Examples include clotting factors, lipoproteins.
Non-Functional Plasma Enzymes: Enzymes in the blood without known functions. Examples include ALT, AST, CK, LDH.
Enzyme Specificity: Each enzyme works optimally on a certain type of substrate, also known as either absolute or relative specificity
Glycogen and Starch: Both are branched polysaccharides with thousands of glucose units, important for glucose storage. Glycogen: in humans and animals. Starch: in plants.
Alcohol, Fats and Waxes: Alcohol: glycerol & fatty acid ester. Fats: ester of fatty acids and glycerol. Waxes: high molecular weight fatty acid and mono-hydroxyl alcohol
Protein Structure: The first structure, primary structure of a protein, is a linear sequence of amino acids. The secondary structure (secondary protein structure) is composed of alpha helices or beta sheets, while Tertiary structure (3D structure) is the three-dimensional shape formed by interactions between the secondary structures. The quaternary structure (quaternary protein structure) is the three dimensional shape formed by interactions between multiple polypeptide chains.
Enzyme Regulation Types: Short-term: Allosteric regulation, reversible covalent modification, proteolytic cleavage, and compartmentalization. Long-term: enzyme synthesis or degradation and enzyme compartmentalization
Monomers and Polymers: Monomers are small, single units, like glucose, amino acids, and nucleotides. Polymers are large molecules made up of repeating monomers, such as starch or proteins.
OH-containing and Sulfur-containing Amino Acids: OH-containing: serine, threonine. Sulfur-containing: cysteine, methionine
High & Low Biological Value Proteins: High biological value proteins (animal-based): contain all essential amino acids needed to build and maintain body proteins. Low biological Value proteins are plant-based (plant-based): deficient in one or more essential amino acids
PCR (Polymerase Chain Reaction): A technique to amplify DNA sequences from a small amount of DNA, useful for diagnosis of diseases.
Gene Cloning: A process to produce many copies of a DNA fragment.
Somatic and Germline Gene Therapy: Somatic gene therapy alters genes in non-reproductive cells and isn't passed on. Germline therapy alters genes in reproductive cells and can be inherited.
Cell Cycle Regulation: Regulation of cell growth and division: Strict regulatory mechanisms ensure balanced cell growth; however, deregulation is associated with several health problems such as uncontrolled cell growth in cancer
Enzyme Regulation: Long term: enzyme synthesis or degradation and enzyme compartmentalization. Short term: allosteric regulation, reversible covalent modification, proteolytic cleavage and compartmentalization.

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Description

Explore the biochemical principles behind reversible enzyme inhibition, focusing on competitive and non-competitive mechanisms. This quiz covers essential concepts such as Km, Vmax, and Lineweaver-Burk plots. Test your understanding of Michaelis-Menten kinetics and the implications for enzyme behavior.