Flashcards
Enzymes
Cards in this deck (12)
- 16 different types of enzymes1. oxidoreductases
2. hydrolases
3. isomerases
4. transferases
5. lyases
6. ligases - 2isozymesdifferent structural forms of a protein that catalyze the same reaction.
- 3oxidoreductasescatalyze oxidation-reduction reactions. Examples - dehydrogenases, oxidases, reductases, peroxidases, catalase, oxygenases, hydroxylases
Electrons are removed from one substrate and added to another. - 4transferasestransfer a chemical group from one molecule to another. Examples - transaldolase, transketolase, acyl, methyl, glucosyl and phosphoryltransferases, kinases, phosphomutases
For example, aminotransferases transfer the amino group to convert an AA to a ketoacid. They require Vitamin B6 - 5hydrolasescatalyze hydrolysis reactions. examples: esterases, glycosidases, peptidases, phosphatases, thiolases, phospholipases, amidases, deaminases, ribonucleases
transfer -OH from water to substrate. Irreversible reaction. Substrate is typically an ester or an amide. - 6lyasesbreak apart a bond, usually a carbon-carbon bond. Can also be carbon-nitrogen, or release CO2 from a B-keto-acid.
Examples - decarboyxlase, aldolases, hydratases, dehydratases, synthases, lyases
if ATP is required, it's called synthetase. If not, it's synthase. - 7isomerasesInvolved with moving a group or a double bond within the same molecule. Examples: racemases, epimerases, isomerases, mutases (not all)
Mutase is when a phosphate is moved from one carbon to another within the same molecule such as occurs with phosphglycerate mutase that converts 2-phosphoglycerate to 3-phosphoglycerate - 8ligasesjoin carbon atoms together, but unlike lyases, they require energy for the reaction and are referred to as synthetases. Also carboxylases. Energy usually comes from ATP.
- 9binding of a substrate by an enzymefor an enzyme to function as a catalyst (which increases the rate of the reaction, but does not change equilibrium or K), it must first bind the substrate and then lower the energy of activation so that the reaction will proceed at a faster rate than it would in the absence of the catalyst. Two prevalent theories exist to explain how substrates bind the enzyme - lock and key theory, and induced-fit theory
- 10lock and key theoryproposes that a binding site for substrate on the enzyme is a rigid entity and only a compound with a particular shape will fit, analogous to how a lock allows only one key to make the proper contact.
- 11induced-fit theoryAssumes that the enzyme is flexible, and after the substrate binds the enzyme, the conformation of the protein changes so that a stable binary complex forms.
- 12—
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- Chapter 10 in Textbook of Biochemistry with Clinical Correlations by Thomas M Devlin
- Created by
- Samantha Scruggs
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