Enzymes and Enzymology

Enzymes = Proteins that act as biological catalysts by accelerating chemical reactions Substrates = Molecules upon which enzymes may act Products = Different molecules produced when enzymes convert substrates Ribozymes = Catalytic RNA molecules

Enzyme's specificity = Comes from its unique three-dimensional structure Enzyme's function = Increase the reaction rate by lowering activation energy Enzyme's consumption in chemical reactions = Not consumed in chemical reactions Enzyme's difference from most other catalysts = Much more specific

Enzymes = Biological catalysts for accelerating chemical reactions Pseudoenzymes = Lost the ability to carry out biological catalysis during evolution Biocatalysts = Catalytic RNA molecules Enzymology = The study of enzymes

Orotidine 5'-phosphate decarboxylase = Allows a reaction that would otherwise take millions of years to occur in milliseconds Chemical properties of enzymes = Like any catalyst and not consumed in chemical reactions Enzyme's speed of conversion = Can make their conversion of substrate to product occur many millions of times faster Metabolic pathways dependence on enzymes = Depend upon enzymes to catalyze individual steps

Number of biochemical reaction types catalyzed by enzymes = More than 5,000 Field of pseudoenzyme analysis = Recognizes that some enzymes have lost the ability to carry out biological catalysis during evolution Equilibrium alteration by enzymes = Do not alter the equilibrium of a reaction Role of ribozymes in biocatalysis = Catalytic RNA molecules

Enzyme denaturation = Disruption to the structure causing a loss of activity Active site = Location of catalytic site and binding site Allosteric site = Site where small molecule binding causes a conformational change Ribozymes = RNA-based biological catalysts

Globular proteins = Enzyme structure type generally acting alone or in larger complexes Catalytic site = Part of the structure directly involved in catalysis Cofactors = Small molecules binding and orienting catalytic sites Ribosome = Complex of protein and catalytic RNA components

Sequence similarity classification = Basis for classifying enzymes into numerous families Non-homologous isofunctional enzymes = Unrelated enzymes with the same enzymatic activity Horizontal gene transfer = May spread genes to unrelated species, especially bacteria Homologous gene displacement = Replacement of endogenous genes by unrelated genes of the same function

Unfolding when heated or exposed to denaturants = Causes disruption to the structure and loss of activity Sizes much larger than substrates = Range from small monomers to very large structures Binding sites for substrates orientation = Located next to the catalytic site RNA-based biological catalysts = Can act alone or in complex with proteins

Substrate binding = First step in enzyme-catalyzed reactions Enzyme denaturation = Linked to temperatures above a species' normal level Allosteric site = Site where small molecule binding causes conformational change Ribozymes = Examples of RNA-based biological catalysts

Anselme Payen discovered the first enzyme, diastase, in 1833 = Anselme Payen German physiologist Wilhelm Kühne first used the term "enzyme" in 1877 = Wilhelm Kühne Eduard Buchner discovered cell-free fermentation and received the Nobel Prize in Chemistry in 1907 = Eduard Buchner James B. Sumner showed that urease and catalase were pure proteins and crystallized them = James B. Sumner

Enzyme activity can be affected by inhibitors and activators = Inhibitors and activators affect enzyme activity Therapeutic drugs and poisons can act as enzyme inhibitors = Therapeutic drugs and poisons can inhibit enzyme activity Enzyme activity decreases significantly outside optimal temperature and pH = Suboptimal temperature and pH decrease enzyme activity Enzymes can be permanently denatured by excessive heat = Excessive heat can permanently denature enzymes

Enzymes can be classified by amino acid sequence similarity or enzymatic activity = Classification based on amino acid sequence similarity or enzymatic activity Names of enzymes are often derived from their substrate or catalyzed reaction = Enzymes named after their substrate or reaction John Howard Northrop and Wendell Meredith Stanley demonstrated that pure proteins can be enzymes = Demonstration of pure proteins being enzymes by Northrop and Stanley The structure of lysozyme was solved by x-ray crystallography in 1965, marking the beginning of structural biology = Solving lysozyme structure marked the beginning of structural biology

Some enzymes are used commercially, such as in the synthesis of antibiotics and household products = Synthesis of antibiotics and household products Enzymes used in commercial applications = Commercial use of enzymes Enzymes used in the industry for various purposes = Industrial applications of enzymes Enzymes employed in manufacturing processes = Use of enzymes in manufacturing