Enzymes and Their Activity Quiz
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Questions and Answers

What is the temperature coefficient (Q10) indicating regarding enzyme activity?

  • A 10°C increase results in a twofold increase in enzyme activity (correct)
  • All enzymes are active at temperatures above 70°C
  • Enzyme activity decreases with increased temperature
  • Enzyme activity remains constant with temperature changes

Most physiological reactions occur at a pH range of 6 to 7.

False (B)

What temperature is ideal for longer-term storage of enzymes?

-20°C

Hemolysis mostly increases ______ concentration.

<p>enzyme</p> Signup and view all the answers

Match the enzyme names with their corresponding EC numbers:

<p>Acid phosphatase = EC 3.1.3.2 Amylase = EC 3.2.1.1 Lactic dehydrogenase = EC 1.1.1.27 Creatine kinase = EC 2.7.3.2</p> Signup and view all the answers

Which enzyme has an EC number of EC 2.6.1.2?

<p>Alanine aminotransferase (D)</p> Signup and view all the answers

What is the primary role of enzymes in biological systems?

<p>To speed up chemical reactions (D)</p> Signup and view all the answers

Repeated freezing and thawing of enzymes is recommended to prevent denaturation.

<p>False (B)</p> Signup and view all the answers

What effect does lactescense have on enzyme concentration?

<p>decreases</p> Signup and view all the answers

Enzymes can only catalyze one specific reaction.

<p>True (A)</p> Signup and view all the answers

What effect does increasing enzyme concentration have on reaction rate?

<p>It increases the reaction rate.</p> Signup and view all the answers

Cofactors are non-protein molecules that must bind to enzymes to ensure their ______.

<p>function</p> Signup and view all the answers

Match the following processes with their corresponding effects on enzymatic reactions:

<p>Increasing enzyme concentration = Increases reaction rate Increasing substrate concentration = Increases reaction rate until saturation Reaching saturation = No further increase in reaction rate Increasing coenzyme concentration = Increases enzymatic activity</p> Signup and view all the answers

Which of the following is a coenzyme that plays a crucial role in enzymatic activity?

<p>NAD (D)</p> Signup and view all the answers

Abnormal levels of enzymes in the serum can indicate tissue damage.

<p>True (A)</p> Signup and view all the answers

What is the primary reason for measuring enzymatic activity in clinical settings?

<p>To diagnose organ damage or disease.</p> Signup and view all the answers

Which theory describes the precise fitting of a substrate into the active site of an enzyme?

<p>Lock and Key Theory (B)</p> Signup and view all the answers

The Induced Fit Theory states that the active site does not change shape when the substrate binds to it.

<p>False (B)</p> Signup and view all the answers

What is the main effect of enzymes on activation energy during physiological reactions?

<p>Enzymes lower the activation energy required for reactions.</p> Signup and view all the answers

The enzyme activity is quantified in ________ or ________.

<p>International Units (IU), Katal Units (KU)</p> Signup and view all the answers

What type of specificity allows an enzyme to combine with substrates in a chemical group?

<p>Group specificity (C)</p> Signup and view all the answers

Match the following types of enzymatic reactions with their definitions:

<p>Zero-order reaction = Reaction rate depends only on enzyme concentration First-order reaction = Reaction rate is directly proportional to substrate concentration</p> Signup and view all the answers

The presence of inhibitors can enhance enzyme activity if the sample is diluted.

<p>False (B)</p> Signup and view all the answers

What is the preferred specimen for measuring enzyme activity?

<p>Serum</p> Signup and view all the answers

Which class of enzymes catalyzes the transfer of a chemical group other than hydrogen from one substrate to another?

<p>Transferases (A)</p> Signup and view all the answers

The active site of an enzyme is a cavity where the substrate interacts with a charged molecule.

<p>True (A)</p> Signup and view all the answers

What term refers to the inactive form of digestive enzymes originally secreted from the organ of production?

<p>proenzyme or zymogen</p> Signup and view all the answers

An enzyme combined with its cofactor is known as a ______.

<p>holoenzyme</p> Signup and view all the answers

Which of the following enzymes catalyzes redox reactions?

<p>Lactate dehydrogenase (C)</p> Signup and view all the answers

Match the following enzyme classes with their functions:

<p>Oxidoreductases = Catalyze redox reactions Hydrolases = Catalyze hydrolysis Lyases = Catalyze removal of groups without hydrolysis Ligases = Join two substrate molecules</p> Signup and view all the answers

An allosteric site is primarily designed for substrate binding.

<p>False (B)</p> Signup and view all the answers

Name one example of a hydrolase enzyme.

<p>Glycosidase or Galactosidase</p> Signup and view all the answers

Which of the following is an example of an inorganic ion that acts as an enzyme activator?

<p>Calcium (A)</p> Signup and view all the answers

All inhibitors compete for the same active site on an enzyme.

<p>False (B)</p> Signup and view all the answers

What is the mechanism of action for competitive inhibitors?

<p>Competitive inhibitors bind to the active site of the enzyme, competing with the substrate.</p> Signup and view all the answers

Increasing the concentration of __________ will not reverse the inhibition caused by non-competitive inhibitors.

<p>substrate</p> Signup and view all the answers

Match the following types of inhibitors with their description:

<p>Competitive Inhibitors = Bind to the active site and compete with the substrate Non-Competitive Inhibitors = Bind to an allosteric site and change enzyme configuration Uncompetitive Inhibitors = Bind only to the enzyme-substrate complex Irreversible Inhibitors = Cause permanent inactivation of the enzyme</p> Signup and view all the answers

What is the reference range for Alkaline Phosphatase (ALP) levels in U/L?

<p>30-90 (C)</p> Signup and view all the answers

What effect does dilution of serum have on reaction rate when a competitive inhibitor is present?

<p>Increases reaction rate (C)</p> Signup and view all the answers

Isoenzymes have identical molecular structures but different catalytic reactions.

<p>False (B)</p> Signup and view all the answers

Alkaline phosphatase is exclusively found in the liver.

<p>False (B)</p> Signup and view all the answers

Name one factor that can affect enzyme levels.

<p>Tissue necrosis</p> Signup and view all the answers

At what temperature is enzymatic activity typically at its optimum?

<p>37°C</p> Signup and view all the answers

Enzymes begin to exhibit __________ above 40°C to 50°C, which can lead to loss of function.

<p>denaturation</p> Signup and view all the answers

Alkaline phosphatase functions to liberate inorganic phosphate from __________.

<p>organic phosphate esters</p> Signup and view all the answers

Which of the following enzyme types binds to the enzyme-substrate complex?

<p>Uncompetitive Inhibitor (A)</p> Signup and view all the answers

Match the isoenzymes of Alkaline Phosphatase with their characteristics:

<p>Liver ALP = Most abundant in plasma Bone ALP = Elevated in osteoblastic activity Placental ALP = Found during pregnancy Intestinal ALP = Involved in digestion</p> Signup and view all the answers

Which of the following is a method used to measure ALP levels?

<p>Kinetic assay (A)</p> Signup and view all the answers

Increased ALP levels are typically seen in growing children.

<p>True (A)</p> Signup and view all the answers

The Lineweaver-Burk plot illustrates the relationship between substrate concentration and __________.

<p>reaction velocity</p> Signup and view all the answers

Which ALP isoform is most heat-stable?

<p>Placental ALP (A)</p> Signup and view all the answers

Hemolysis does not interfere with ALP measurement.

<p>False (B)</p> Signup and view all the answers

What concentration of solution inhibits Bone ALP?

<p>3M urea</p> Signup and view all the answers

ALP is inhibited by ______.

<p>phosphorus</p> Signup and view all the answers

Match the ALP measurement methods with their corresponding substrates:

<p>Bowers and McComb = Phenylphosphate King-Armstrong = Alpha-naphthol phosphate Bess, Lowry, and Brock = Para-nitro phenyl phosphate Moss = Buffered phenolphthalein phosphate</p> Signup and view all the answers

Which of the following is a condition associated with increased ALP levels?

<p>Obstructive jaundice (C)</p> Signup and view all the answers

Ingestion of food decreases intestinal ALP levels.

<p>False (B)</p> Signup and view all the answers

What is the primary pH environment used in the Bowers-McComb method?

<p>10.15</p> Signup and view all the answers

Which blood groups show higher intestinal ALP levels after a fatty meal?

<p>B and O (B)</p> Signup and view all the answers

Regan ALP is found in various types of cancer and is the least heat-stable ALP.

<p>False (B)</p> Signup and view all the answers

What is the primary use of placental alkaline phosphatase (PLAP)?

<p>As a tumor marker.</p> Signup and view all the answers

The presence of intestinal ALP isoenzyme in serum depends on the blood group and the _______ gene.

<p>secretor</p> Signup and view all the answers

Match the ALP types with their related conditions:

<p>Regan ALP = Breast cancer Nagao ALP = Adenocarcinoma of the pancreas Bone ALP (B1x) = Low bone mineral density Placental ALP (PLAP) = Germ cell tumors</p> Signup and view all the answers

Elevated serum ALP levels can indicate issues in which of the following conditions?

<p>Liver problems (B)</p> Signup and view all the answers

Transient low serum ALP levels can occur after blood transfusion.

<p>True (A)</p> Signup and view all the answers

Which ALP activity is linked to low bone mineral density in patients with chronic kidney disease?

<p>Bone ALP isoform (B1x)</p> Signup and view all the answers

Flashcards

Lock and Key Theory

The enzyme's active site changes shape to fit the substrate perfectly, like a key fitting into a lock.

Induced Fit Theory

The enzyme's active site changes shape to accommodate the substrate, similar to a glove adapting to a hand.

Zero-order reaction

The rate of a reaction depends only on the enzyme concentration.

First-order reaction

The reaction rate is directly proportional to the substrate concentration.

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Absolute Specificity

The enzyme only combines with one specific type of substrate and catalyzes only one reaction.

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Group Specificity

The enzyme combines with all substrates within a particular chemical group.

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Bond Specificity

The enzyme reacts with certain chemical bonds, regardless of the rest of the molecule.

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Enzymatic Activity

The amount of product formed per unit time, representing the enzyme's activity.

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Enzymes

Proteins produced by living cells that speed up chemical reactions in organic matter.

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Enzyme Concentration

The amount of enzyme present in a sample, directly impacting the speed of the reaction. More enzyme, faster reaction.

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Substrate Concentration

The amount of the substance that an enzyme acts upon. Increasing substrate concentration increases reaction speed, up to a point.

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Cofactors

Non-protein molecules essential for enzyme function. They bind to enzymes, assisting in their work.

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Coenzymes

Organic cofactors that act as second substrates essential for enzyme activity. Increased coenzyme concentration increases reaction rate.

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Saturation kinetics

The state where adding more substrate won't make the reaction go faster because all the enzymes are busy.

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Diagnostic significance of enzymes

Abnormal levels of enzymes in the blood can indicate damage to specific organs or tissues.

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What is the temperature coefficient (Q10)?

The temperature coefficient (Q10) describes the increase in enzyme activity for every 10°C rise in temperature. Typically, enzyme activity doubles for each 10°C increase. However, excessive heat can lead to enzyme denaturation and inactivation.

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How does pH affect enzyme activity?

Most enzymes function optimally within a specific pH range, often around 7-8. Extreme pH values can denature the enzyme, altering its structure and hindering its ability to bind to substrates.

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How do low temperatures affect enzymes?

Low temperatures (refrigeration or freezing) can temporarily inactivate enzymes. While most enzymes can be reactivated by warming, repeated freezing and thawing can damage their structure, leading to irreversible denaturation.

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How do hemolysis and lactescense affect enzyme concentration?

Hemolysis, or the breakdown of red blood cells, typically increases enzyme concentration in a sample. Conversely, lactescense (milky appearance) generally decreases enzyme concentration due to the presence of lipid particles.

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What is the Enzyme Commission (EC) classification system?

The Enzyme Commission (EC) developed a classification system to provide a unique name and number for each enzyme. This system groups enzymes based on their function (six main classes) and identifies the specific substrate and reaction catalyzed.

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What is an enzyme's systematic name?

An enzyme's systematic name is generated using the EC classification number, which reflects the enzyme's catalytic reaction. It provides a detailed and unique description of the enzyme's function.

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What does the EC number tell us about an enzyme?

The first digit in an enzyme's EC number indicates its general class, such as oxidoreductases, transferases, or hydrolases. The subsequent digits provide increasing specificity, narrowing down the enzyme's function within its class.

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What is the significance of the final digit(s) in the EC number?

The last digit(s) of the EC number are specific to each enzyme within a particular subclass. This allows for a unique identification of each enzyme within a given class and subcategory.

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What is Alkaline Phosphatase?

Alkaline phosphatase (ALP) is an enzyme found in various tissues like the liver, bone, placenta, and intestines. It helps remove phosphate groups from organic molecules.

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Why are elevated ALP levels significant?

ALP levels increase when certain tissues experience damage or accelerated activity. This often occurs with bone disorders, liver diseases, pregnancy, or placental problems.

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What does elevated ALP usually indicate in adults?

Though common in growing children due to bone activity, elevated ALP levels in adults are usually a sign of tissue damage.

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What is a kinetic assay for ALP?

A test that measures the rate of change in absorbance over time using specific substrates, typically at 340 nm.

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What is a non-kinetic assay for ALP?

A test that measures the final concentration of a product at a specific time interval.

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What does the 'Lineweaver-Burk plot' depict?

The 'Lineweaver-Burk plot' illustrates the relationship between substrate concentration and reaction velocity in enzyme kinetics.

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What are ALP isoenzymes?

ALP has different forms found in different tissues. These forms are called isoenzymes.

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What's the importance of Liver ALP?

Liver ALP is the most abundant form in the bloodstream and is often a key indicator of liver health.

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Active Site

A special pocket on an enzyme where the substrate binds and the reaction happens. It is a specific region with a unique shape and amino acid composition.

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Allosteric Site

A site on an enzyme that's different from the active site. Regulatory molecules can attach here, influencing enzyme activity.

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Holoenzyme

Enzyme + Cofactor. This is the complete, active form of an enzyme, ready to work.

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Apoenzyme

The protein part of an enzyme, without its cofactor. It's inactive without its partner.

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Proenzyme or Zymogen

An inactive form of an enzyme that gets activated later, often by specific conditions or enzymes in the body.

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Denaturation

The loss of normal enzyme structure, leading to a loss of function. It can be caused by heat, pH changes, or chemicals.

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Inorganic Ion Activators

Inorganic ions, like calcium, zinc, chloride, magnesium and potassium, that alter an enzyme's shape to bind to the substrate properly.

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Metalloenzymes

Inorganic ions attached to a molecule that act as enzyme activators.

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Enzyme Inhibitor

A molecule that slows down or prevents an enzymatic reaction by interfering with its process.

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Competitive Inhibitor

A type of inhibitor that binds to the active site of an enzyme, competing with the substrate for the same binding site.

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Non-competitive Inhibitor

An inhibitor that binds to an enzyme at a different site than the active site, known as an allosteric site, altering the shape of the active site and stopping the reaction.

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Uncompetitive Inhibitor

An inhibitor that binds only to the enzyme-substrate complex, not the enzyme alone or substrate alone.

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Optimal Temperature

The temperature at which an enzyme exhibits its highest activity.

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Enzyme Denaturation

The process where the structure of an enzyme is disrupted, leading to a loss of its activity.

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Effect of Temperature on Denaturation Rate

The rate of denaturation increases as the temperature rises.

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Regan ALP

A type of Carcinoplacental ALP found in various cancers like lung, breast, and ovarian, known for its high heat stability, resistance to 65 °C for 30 minutes, and inhibition by phenylalanine.

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Nagao ALP

Another type of Carcinoplacental ALP often found in pancreatic and bile duct adenocarcinoma, similar to Regan ALP but inhibited by L-leucine and phenylalanine.

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Elevated ALP

Elevated levels are often associated with liver problems, particularly obstructive jaundice, due to an increased rate of ALP synthesis. Increased in conditions with conjugated bilirubin flow problems, like biliary tract obstruction and cholestasis.

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Bone ALP

The form of ALP specifically present in bone. Elevated levels can be seen in conditions like Paget's disease, osteosarcoma, and metastatic bone tumors, indicating increased osteoblastic activity.

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Bone ALP Isoform (B1x)

Present in serum of dialysis patients and linked to low bone mineral density (BMD) in individuals with chronic kidney disease, particularly affecting trabecular bone. Also elevated in cases of abortions and difficult pregnancies.

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Placental ALP (PLAP)

A tumor marker found in serum and CSF, primarily used to detect germ cell tumors. Elevated levels in CSF can help differentiate pinealoma from germ cell tumors.

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ALP Inactivation and Activation

ALP is inactivated by EDTA, making serum the preferred sample for analysis. Magnesium ions are crucial for ALP activation.

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Electrophoresis of ALP Isoenzymes

This technique separates ALP isoenzymes based on their migration rate in an electric field. Liver and bone ALPs migrate faster (anodal) while intestinal ALP migrates slower (cathodal).

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Heat Fractionation/Stability Test

A laboratory test that uses different temperatures to differentiate between various ALP isoforms based on their heat stability. Placental ALP is the most heat-stable, while bone ALP is the least.

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Chemical Inhibition Test

This test utilizes specific chemical inhibitors to identify ALP isoforms by their sensitivity to these inhibitors. For example, phenylalanine inhibits placental and intestinal ALPs, while 3M urea inhibits bone ALP.

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Bowers-McComb (Szasz Modification)

This method, considered the gold standard for ALP measurement, employs a continuous monitoring technique at pH 10.15 and measures the reaction at 405 nm. It is frequently used in routine ALP assays.

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What raises ALP levels?

A substance that increases serum ALP levels, often indicating liver or bone disease.

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Conditions that cause increased ALP

Increased ALP levels can be associated with conditions like obstructive jaundice, Paget's disease, osteomalacia, and rickets.

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Zinc and Magnesium's role in ALP

Zinc is crucial for ALP function, and magnesium helps activate the enzyme.

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Impact of food on ALP

Eating food can increase intestinal ALP levels, leading to temporary elevations in plasma ALP.

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Factors affecting ALP accuracy

Hemolysis, presence of lipids (fatty meals), and low storage temperatures can all lead to inaccurate ALP measurements.

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Study Notes

Enzyme Activity

  • Enzymes are proteins that accelerate chemical reactions
  • Enzymes are crucial in diagnosing and managing diseases
  • Enzymes are located in tissues and cells
  • Enzymes are mostly confined within cells
  • Enzymes are frequently produced by living cells
  • They are involved in chemical reactions
  • Their presence in serum is evidence of organ damage

Factors Affecting Enzymatic Reactions

  • Enzyme Concentration: Higher enzyme concentration leads to faster reactions because more enzymes are available to bind with the substrate
  • Substrate Concentration: Increasing substrate concentration increases the reaction rate initially, but the reaction rate plateaus as the concentration continues to increase
  • Cofactors: These are non-protein entities that must bind to particular enzymes to achieve their absolute enzymatic activity
    • Coenzymes: These are organic cofactors that are essential for enzyme activity
      • Examples include Nicotinamide adenine dinucleotide (NAD) and Nicotinamide adenine dinucleotide phosphate (NADP)
  • Temperature: Optimal temperature for most enzymatic activity is around 37°C. However, exceeding 40-50°C will result in denaturation and enzyme inactivation
  • pH: Most physiologic reactions occur in the pH range of 7-8. Extreme pH levels may denature enzymes or change their active site

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Test your knowledge on enzyme activity and characteristics in this quiz. Covering topics like temperature coefficients, ideal storage conditions, and the role of cofactors, this quiz is essential for biology students. Match enzymes with their EC numbers and understand the factors affecting enzymatic reactions.

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