Textbook Question
The meat tenderizer used in cooking is primarily papain, a protease enzyme isolated from the fruit of the papaya tree. Why do you suppose papain is so effective at tenderizing meat?
Ch.19 Enzymes and Vitamins
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch.1 Matter and Measurements27
- Ch.2 Atoms and the Periodic Table20
- Ch.3 Ionic Compounds8
- Ch.4 Molecular Compounds23
- Ch.5 Classification & Balancing of Chemical Reactions12
- Ch.6 Chemical Reactions: Mole and Mass Relationships28
- Ch.7 Chemical Reactions: Energy, Rate and Equilibrium64
- Ch.8 Gases, Liquids and Solids24
- Ch.9 Solutions52
- Ch.10 Acids and Bases25
- Ch.11 Nuclear Chemistry22
- Ch.12 Introduction to Organic Chemistry: Alkanes57
- Ch.13 Alkenes, Alkynes, and Aromatic Compounds47
- Ch.14 Some Compounds with Oxygen, Sulfur, or a Halogen50
- Ch.15 Aldehydes and Ketones45
- Ch.16 Amines42
- Ch.17 Carboxylic Acids and Their Derivatives57
- Ch.18 Amino Acids and Proteins82
- Ch.19 Enzymes and Vitamins63
- Ch.20 Carbohydrates44
- Ch.21 The Generation of Biochemical Energy65
- Ch.22 Carbohydrate Metabolism45
- Ch.23 Lipids42
- Ch.24 Lipid Metabolism33
- Ch.25 Protein and Amino Acid Metabolism24
- Ch.26 Nucleic Acids and Protein Synthesis45
McMurry8th EditionFundamentals of General, Organic, and Biological ChemistryISBN: 9780134015187Not the one you use?Change textbook
Chapter 19, Problem 63
One mechanism by which lead exerts its poisonous effect on enzymes can be stopped by chelation therapy with EDTA. Describe this type of lead poisoning and explain why it is reversible.
Verified step by step guidance1
Lead poisoning occurs when lead ions (Pb²⁺) bind to the active sites of enzymes or other critical biomolecules, disrupting their normal function. This happens because lead can mimic other essential metal ions like calcium (Ca²⁺), zinc (Zn²⁺), or iron (Fe²⁺), which are required for enzymatic activity.
When lead binds to enzymes, it forms strong coordination complexes with the enzyme's functional groups, such as sulfhydryl (-SH) or carboxyl (-COOH) groups. This binding alters the enzyme's structure and prevents it from catalyzing reactions effectively.
Chelation therapy with EDTA (ethylenediaminetetraacetic acid) works by introducing a molecule that has multiple binding sites (ligands) capable of forming a stable complex with lead ions. EDTA has four carboxylate groups and two amine groups, which can coordinate with Pb²⁺ ions, effectively sequestering them.
The EDTA-lead complex is highly stable and water-soluble, allowing it to be excreted from the body through the kidneys. This process removes lead from the enzymes and other tissues, restoring the enzyme's ability to function normally.
This type of lead poisoning is reversible because the binding of lead to enzymes is not covalent (permanent). Once the lead is removed via chelation therapy, the enzyme's active site can return to its original state, allowing normal biological activity to resume.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
4mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Lead Poisoning
Lead poisoning occurs when lead builds up in the body, often due to exposure to lead-based paints, contaminated water, or industrial processes. It can interfere with various bodily functions, particularly affecting the nervous system and the production of hemoglobin. Symptoms may include abdominal pain, constipation, fatigue, and neurological impairments, making it a serious health concern.
Recommended video:
Guided course
02:07
Naming Ionic Hydrates Example 1
Chelation Therapy
Chelation therapy is a medical treatment that involves the administration of chelating agents, such as EDTA, which bind to heavy metals in the bloodstream. This binding forms a stable complex that can be excreted from the body, thereby reducing the levels of toxic metals like lead. Chelation therapy is particularly effective in cases of acute lead poisoning, as it helps to mitigate the harmful effects of lead on enzymes and other biological systems.
Reversibility of Lead Poisoning
The reversibility of lead poisoning through chelation therapy is due to the ability of chelating agents to remove lead from the body before it causes permanent damage. When lead is chelated, it is effectively sequestered and eliminated, allowing the body to recover and restore normal enzyme function. This process highlights the importance of early intervention in lead exposure cases, as timely treatment can prevent long-term health consequences.
Recommended video:
Guided course
3:26Enzyme Inhibition Concept 2
Related Practice
Textbook Question
The text discusses three forms of enzyme inhibition: uncompetitive inhibition, competitive inhibition, and irreversible inhibition.
b. What kinds of bonds are formed between an enzyme and each of these three kinds of inhibitors?
Textbook Question
What kind of inhibition (uncompetitive, competitive, or irreversible) is present in each of the following:
c. The antibiotic deoxycycline inhibits the bacterial enzyme collagenase, slowing bacterial growth. Deoxycycline does not fit into the active site of collagenase and binds elsewhere on the enzyme.
Textbook Question
What kind of inhibition (uncompetitive, competitive, or irreversible) is present in each of the following:
a. Penicillin is used to treat certain bacterial infections. Penicillin is effective because it binds to the enzyme glycopeptide transpeptidase and does not dissociate.
Textbook Question
What are the cellular advantages to feedback inhibition?
Textbook Question
Why do allosteric enzymes have two types of binding sites?