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Enzyme, Catalysts and Reactions

Enzymes, or biological catalysts, are three-dimensional globular proteins. Enzymes are integral in biological systems, they function to speed up metabolic reactions by lowering the activation energy of the reaction. Activation energy is the minimum amount of energy that is required to initiate atoms or molecules to a condition in which they can undergo chemical transformation of physical transport1. Examples of enzymes are amylases, proteases, and lipases found in the human digestive system.

Due to the complex folding in proteins, enzymes have substrate specificity. Binding of substrates occur at the active site, and this process can be shown through the ‘Lock and Key’ model or the ‘Induced Fit’ model. Enzymes can use cofactors, helper molecules, in catalyzing reactions. Cofactors can be classified as tightly bound or loosely bound to the enzyme, and organic or inorganic.  

Factors that affect enzyme activity are enzyme concentration, substrate concentration, temperature, pH and inhibitors. Derivation from optimal temperature and pH conditions denature the enzyme – the quaternary, tertiary and secondary structure of the protein is modified. Denaturation causes the enzyme’s active site to lose substrate specificity, and overall enzyme function.  Inhibitors act to decrease enzyme activity by binding and effectively blocking the active site, and there are four main types: competitive, uncompetitive, non-competitive and mixed.

Enzyme catalysis can be defined by their Vmax and Km which are both important in the Michaelis-Menten formula of enzyme kinetics. Vmax is the maximal velocity of enzyme catalysis, or how fast the enzyme can degrade the substrate. Km is substrate concentration where half of the enzyme’s active site are occupied (½ Vmax), this is called the Michaelis Constant. 



1 Activation Energy. (n.d.). In Encyclopedia Britannica online. Retrieved from

Properties of Enzymes and Catalysis

Which of the following statements is true of enzyme catalysts? (a) They are generally equally active on D and L isomers of a given substrate (b) They can increase the reaction rate for a given reaction by a thousand-fold or more (c) They can increase the equilibrium constant for a given reaction by a thousand-fold or more.

Hypothetical experimental scenario or data

For this assignment, use your understanding of enzymes along with your scientific reasoning skills. This assignment provides you the opportunity to demonstrate your grasp of this module's concepts along with your capacity to interpret scientific data and draw conclusions from it. A biologist is studying the behavior of a newl

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Calculations for Determining a Titer

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Lab Report on Enzyme Kinetics

Sample Laboratory Report for a 400 level biochemistry lab for Majors. Topic: Enzyme Kinetics Include thorough introduction, Methods, Data, Results & Discussion sections. No graphs are provided!

Please choose the correct option

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You characterize a new enzyme's kinetics.

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Question about Enzyme properties.

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Here is the problem I have to solve: If 10 g of pure carbonic anhydrase catalyzes the hydration of 0.30 g of carbon dioxide in 1 min at 37 degrees C under optimal conditions, what is the turnover number (kcat) of carbonic anhydrase (in units of min-1)? I have already calculated the turnover number, which is 2.0 x 107 min-1,

Enzymes inhibitors

Compare competitive and noncompetitive in terms of A) how Km is effected in presence of inhibitor, B) how Vmax is effected in presence of inhibitor, C) where inhibitor would bind to the enzyme

Enzyme Kinetics

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Enzymes and Kinetics

I need help on how to approach this problem: What is the Km of an enzyme if, at [S] = 10^-3 M, 25% of the maximum velocity of the reaction is obtained? What is the ratio of substrate concentrations of a reaction proceeding at 90% and 10% of Vmax, respectively? ------- I know the basis of enzyme kinetics. I just don't


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Allosteric Enzymes

Discuss the different methods by which allosteric enzymes are regulated, and define allosteric.

Enzyme Catalyzed Reactions

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Michaelis-Menten Method; Effect of pH on Enzyme

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Discussing Enzyme Proteins

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Structure of enzyme protiens, and how they fulfill their biological role

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10.You have just completed a meal consisting of a steak , baked potato and a vegetable. What enzymes would be released to digest this meal? From where would each of these be released? Why is there more than one protein digesting enzyme?

Enzyme Kinetics: Understanding the Henri-Michaelis-Menten equation/model.

An enzyme with a Km of 0.36 mM was assayed using substrate concentrations of 3 x 10E-7 M, 9.5 x 10E-5 M, 1.5 x 10E-4, 1.16x10E-3, 3 x 10E-3 M, 0.01 M, 0.08 M. At a substrate concentration of 0.08 M, the initial velocity was 192 nM/min. Calculate the initial velocity at each of the other substrate concentrations. Graph the cal