30 Questions
What are enzymes?
Proteins that act as biological catalysts
What do enzymes act upon?
Substrates
What is the study of enzymes called?
Enzymology
What is the unique feature of an enzyme's specificity?
It comes from its unique three-dimensional structure
How do enzymes increase the reaction rate?
By lowering the activation energy
What is a unique property of orotidine 5'-phosphate decarboxylase?
It allows a reaction that would otherwise take millions of years to occur in milliseconds
What are catalytic RNA molecules called?
Ribozymes
How do enzymes differ from most other catalysts?
They do not alter the equilibrium of a reaction
What recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis?
Pseudoenzyme analysis
What are the molecules converted by enzymes known as?
Products
What is the term used to describe unrelated enzymes that have the same enzymatic activity?
Non-homologous isofunctional enzymes
What determines the catalytic activity of an enzyme?
Sequence of the amino acids
What unfolds enzyme structures, causing a loss of activity?
Chemical denaturants
Where is the catalytic site located in an enzyme?
Next to one or more binding sites
What are allosteric sites in enzyme structures responsible for?
Causing a conformational change that increases or decreases activity
What is the function of ribozymes?
Acting as biological catalysts
What is the range of sizes for enzymes in terms of amino acid residues?
62 to over 2,500 residues
What can horizontal gene transfer do in relation to non-homologous isofunctional enzymes?
Spread genes to unrelated species
What is the structure of enzymes generally described as?
Globular proteins
What is the role of the remaining majority of the enzyme structure?
Maintain the precise orientation and dynamics of the active site
What did German physiologist Wilhelm Kühne first use in 1877?
The term 'enzyme'
How are enzymes usually named?
With the suffix '-ase' combined with the name of the substrate or the type of reaction
What allowed the structures of enzymes to be solved?
The discovery that enzymes could be crystallized
When was the first enzyme, diastase, discovered?
1833
What did the International Union of Biochemistry and Molecular Biology develop to classify enzymes?
EC numbers
What affects enzyme activity significantly?
Temperature and pH
What is denaturation?
When enzymes are exposed to excessive heat
What did the discovery that enzymes could be crystallized lead to?
The solving of enzyme structures by x-ray crystallography
What can alter enzyme activity?
Inhibitors and activators
How are enzymes classified?
Based on amino acid sequence similarity or enzymatic activity
Study Notes
Enzyme Discovery and Classification
- Enzyme activity can be altered by inhibitors and activators
- Therapeutic drugs and poisons often function as enzyme inhibitors
- Enzyme activity is significantly affected by temperature and pH
- Denaturation occurs when enzymes are exposed to excessive heat
- Enzymes are used in commercial applications such as the synthesis of antibiotics and household products like biological washing powders and meat tenderizer
- The first enzyme, diastase, was discovered by French chemist Anselme Payen in 1833
- German physiologist Wilhelm Kühne first used the term "enzyme" in 1877
- Enzymes are usually named according to the reaction they carry out, with the suffix "-ase" combined with the name of the substrate or the type of reaction
- The biochemical identity of enzymes was still unknown in the early 1900s
- The discovery that enzymes could be crystallized allowed their structures to be solved by x-ray crystallography
- Enzymes can be classified based on amino acid sequence similarity or enzymatic activity
- The International Union of Biochemistry and Molecular Biology developed a nomenclature for enzymes, the EC numbers, to classify enzymes based on their mechanism and specificity
Test your knowledge of enzyme discovery and classification with this quiz. Explore the impact of inhibitors and activators on enzyme activity, the historical milestones in enzyme discovery, and the classification systems used to categorize enzymes based on their structure and function.
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