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What is the primary role of enzymes in biochemical reactions?
What is the primary role of enzymes in biochemical reactions?
What is the chemical nature of all enzymes except ribozymes?
What is the chemical nature of all enzymes except ribozymes?
What is the non-protein part of a complex protein enzyme?
What is the non-protein part of a complex protein enzyme?
What is the term for the region of an enzyme that binds to the substrate?
What is the term for the region of an enzyme that binds to the substrate?
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What is the result of the reaction after the enzyme-substrate complex forms?
What is the result of the reaction after the enzyme-substrate complex forms?
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What is the theory that proposes the active site of the enzyme is complementary in shape to the substrate?
What is the theory that proposes the active site of the enzyme is complementary in shape to the substrate?
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What is the term for an enzyme that contains a metal ion as a prosthetic group?
What is the term for an enzyme that contains a metal ion as a prosthetic group?
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What is the temporary association formed between the enzyme and substrate?
What is the temporary association formed between the enzyme and substrate?
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What is the result of the enzyme-substrate complex dissociating?
What is the result of the enzyme-substrate complex dissociating?
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What is the term for the reactant that binds to the enzyme and forms a temporary association?
What is the term for the reactant that binds to the enzyme and forms a temporary association?
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What is the primary significance of analyzing enzymes in blood plasma?
What is the primary significance of analyzing enzymes in blood plasma?
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What happens to the plasma concentration of a released enzyme following injury?
What happens to the plasma concentration of a released enzyme following injury?
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What is the typical site of quantitative analysis for released enzymes?
What is the typical site of quantitative analysis for released enzymes?
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What is lipoprotein lipase?
What is lipoprotein lipase?
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What information can be gained from analyzing the activity of released enzymes or proteins?
What information can be gained from analyzing the activity of released enzymes or proteins?
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What is the significance of analyzing the levels of certain enzymes in plasma?
What is the significance of analyzing the levels of certain enzymes in plasma?
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What happens to enzymes following cell death or injury?
What happens to enzymes following cell death or injury?
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What is the primary application of enzyme analysis in clinical diagnosis?
What is the primary application of enzyme analysis in clinical diagnosis?
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Which of the following is NOT a site for quantitative analysis of released enzymes?
Which of the following is NOT a site for quantitative analysis of released enzymes?
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What is the significance of released enzymes in diagnosis?
What is the significance of released enzymes in diagnosis?
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Which class of enzymes catalyzes the transfer of moieties such as glycosyl, methyl, or phosphoryl groups?
Which class of enzymes catalyzes the transfer of moieties such as glycosyl, methyl, or phosphoryl groups?
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What is the result of the substrate binding to the enzyme?
What is the result of the substrate binding to the enzyme?
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What is the function of ligases?
What is the function of ligases?
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What is the origin of the word 'enzyme'?
What is the origin of the word 'enzyme'?
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What is the purpose of translocases?
What is the purpose of translocases?
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What is the name of the class of enzymes that catalyzes oxidations and reductions?
What is the name of the class of enzymes that catalyzes oxidations and reductions?
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What is the characteristic of lyases?
What is the characteristic of lyases?
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What is the function of isomerases?
What is the function of isomerases?
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What is the name of the method for naming enzymes that involves adding the suffix –ase to the name of the substrate?
What is the name of the method for naming enzymes that involves adding the suffix –ase to the name of the substrate?
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How many classes of enzymes are there?
How many classes of enzymes are there?
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What is the primary purpose of the enzyme nomenclature system developed by the IUBMB?
What is the primary purpose of the enzyme nomenclature system developed by the IUBMB?
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What does the first digit in an EC number represent?
What does the first digit in an EC number represent?
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What is the reaction type of the enzyme with EC number 1.1.1.1?
What is the reaction type of the enzyme with EC number 1.1.1.1?
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What is the function of the third digit in an EC number?
What is the function of the third digit in an EC number?
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What is the advantage of using assays of catalytic activity to detect enzymes?
What is the advantage of using assays of catalytic activity to detect enzymes?
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What is the EC number of the enzyme hexokinase?
What is the EC number of the enzyme hexokinase?
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What is the name of the phosphoryl acceptor in the reaction catalyzed by hexokinase?
What is the name of the phosphoryl acceptor in the reaction catalyzed by hexokinase?
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What is the type of reaction catalyzed by the enzyme with EC number 1.1.1.1?
What is the type of reaction catalyzed by the enzyme with EC number 1.1.1.1?
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What is the purpose of the IUBMB's enzyme nomenclature system?
What is the purpose of the IUBMB's enzyme nomenclature system?
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What is the class of the enzyme hexokinase?
What is the class of the enzyme hexokinase?
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Study Notes
Enzymes: Biological Catalysts
- Enzymes accelerate biochemical reactions in living organisms by lowering the energy of activation without being altered or consumed.
- All enzymes are proteins, except for ribozymes, which are RNA-based.
Chemical Nature of Enzymes
- There are two types of protein enzymes: simple and complex (conjugated) proteins.
- Simple protein enzymes are formed of protein only.
- Complex (conjugated) protein enzymes are formed of a protein part (apoenzyme) and a non-protein part (cofactor).
- The non-protein part can be a coenzyme (organic, thermo-labile, and loosely attached) or a prosthetic group (inorganic, thermo-stable, and tightly attached).
Enzymatic Reaction Steps
- The five steps of enzymatic reaction are:
- Substrate approaches active site
- Enzyme-substrate complex forms
- Substrate is transformed into products
- Products are released
- Enzyme is recycled
Enzyme-Substrate Binding
- The "lock and key" model proposes that the active site of an enzyme is complementary in shape to the substrate.
- The "induced fit" theory suggests that the catalytic site of an enzyme is not fully formed until the substrate binds, causing changes in the shape of the active site.
Enzyme Classification
- Enzymes are grouped into 6+1 classes:
- Oxidoreductases (catalyze oxidations and reductions)
- Transferases (catalyze transfer of moieties)
- Hydrolases (catalyze hydrolytic cleavage of covalent bonds)
- Lyases (catalyze cleavage of covalent bonds by atom elimination)
- Isomerases (catalyze geometric or structural changes within a molecule)
- Ligases (catalyze the joining together of two molecules)
- Translocases (catalyze the movement of ions or molecules across membranes)
Enzyme Nomenclature
- Enzyme names are formed from the Greek words "en" (meaning inside) and "zyme" (meaning yeast).
- There are three methods for naming enzymes:
- Old trivial names (e.g., pepsin and trypsin)
- Substrate name with the suffix "-ase" added (e.g., lactase and sucrase)
- Two words, one for the substrate and the other for the type of reaction (e.g., succinate dehydrogenase and pyruvate decarboxylase)
- The International Union of Biochemistry and Molecular Biology (IUBMB) developed an unambiguous system of enzyme nomenclature using a unique name and code number (EC number) for each enzyme.
Enzyme Commission (EC) Number
- Each enzyme has a numerical code (EC number) consisting of four digits separated by dots:
- The first digit denotes the class (reaction type) of the enzyme
- The second digit denotes the functional group upon which the enzyme acts
- The third digit denotes the substrate/acceptor
- The fourth digit denotes the serial number of the enzyme (individual enzyme number)
The Catalytic Activity of Enzymes
- Assays of the catalytic activity of enzymes are used in research and clinical laboratories to detect and quantify enzyme concentration.
- The analysis of certain enzymes in blood plasma aids in the diagnosis of several disease processes.
Principal Serum Enzymes Used in Clinical Diagnosis
- Quantitative analysis of the activity of released enzymes or other proteins in plasma or serum provides information concerning diagnosis, prognosis, and response to treatment.
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Description
Learn about enzymes, biological catalysts that accelerate biochemical reactions in living organisms. Understand their chemical nature, including simple and complex proteins.
