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Ending enzymes with an INTRO.

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Enzymes serve the purpose of being “biological catalysts” in that is “speeds” up the rate of chemical reactions. Enzymes are highly specific (absolute or relative) and selective, meaning that they catalyze only a certain type of substrate to form a product. Absolute specificity, meaning that the enzyme will catalyze one type of substrate alone. On the other hand, in relative specificity, the enzyme would catalyze another substrate type that has the same bond type and structure similar to the complimentary substrate for the particular enzyme.

Enzyme + Substrate                  Product

Figure1 below- the various types of enzymes and their definition

Image

Nearly all enzymes are considered proteins. The design of a particular site on the enzyme, the active site, determines if which substrate would be complimentary. “Amino acid residues” are located on the “cleft” of the active site on the enzyme. Substituent groups are contained within these groups and this is where the catalysis of the substrate takes place. This is so because an enzyme-substrate complex is formed when hydrogen and ionic bonding occurs because of the binding of the active site and the substrate molecule. Enzymes show relative or absolute specificity. Relative, meaning it would bind to another type of substrate if the substrate resembles the complimentary one of the enzyme. However absolute specificity reveals that the enzyme would only bind to one particular type of substrate molecule and no others. Part of the experiment is to show how enzymes reaction rate is affected by substrate type. How specific enzymes are will be revealed by that method. During catalyzing reactions, enzymes may introduce some cofactors such as inorganic and organic molecules to assist. Nearly all living cells need enzymes to sustain life because they maintain the rates of reactions at an appropriate value. Enzymes work on the principle of lowering a reaction’s activation energy without being consumed by the reactions as well as they do not change the reactions’ equilibrium. Various molecules could afflict the activity of enzymes thus changing the speed of the process. If an enzyme is broken down into is subsequent amino acid then its ability to perform catalysis will be destroyed. Primary, secondary, tertiary and quaternary designs of an enzyme –protein are valid information for its catalysis purposes.

Image

Figure 2 shows the designs of protein:Upon disruptions of the enzyme-protein’s active site, these various structures will cooperatively change (eg. Denaturation but does not affect the primary structure) affecting catalysis.

Molecules such as activators which increase activity and inhibitors which slow down the reaction rate attributes to catalytic activity of an enzyme. Temperature, chemical environment such as pH, concentration of substrate and pressure also tampers with the activity of enzymes. The experiment also deals with temperature on enzyme action as well. Boiling an enzyme far surpasses the optimum temperature and so leads to denaturation. Boiling the enzyme affects the, “ hydrogen bonds, Van der waals forces, hydrophobic interactions and electrostatic interactions,” which is responsible for keping thetertiary as well as quaternary design of enzymes. Boiling thus affects “spatial configuration” of revealed residues on the active site of the enzyme. The enzyme needs this in order to bind to the relevant substrate. . In enzyme kinetics, there are four types of  reversable inhibitors. These include competitive, non-competitive, uncompetitve and mixed inhibition.

Image

Figure 3 above shows Lineweaver- Burk plots for the various types of inhibition.

Table 1 below shows the characteristics of the following inhibitors mentioned above.

Type of inhibitor

Does inhibitor resemble substrate

Inhibitor binds where

Effects on           V-max

Effect on Km

Competitive

Yes

Free enzyme alone

No change

Increase

Non-competitive

No

Free enzyme and Enzyme-substrate complex

Decreases

No change

Uncompetitive

No

Enzyme-substrate complex

Decrease

Decrease

Mixed

No

Allosteric site, free enzyme or Enzyme substrate complex

Decrease

Increases or decreases

Figure 4Image

Figure 4 above: The graph illustrates that when Vmax is reached, the point of saturation where all the active site of the enzyme have been binded to, increasing the concentration of the substrate would have no effect on the rate of the reaction hence the tapering of the curve at the saturation point.The rate will drastically increase as there are more substrates to collidewith the enzyme hence the steep increase of the graph which would remain so until the saturation point is reached.

Image

Figure 5: Graph illustrating the effect of temperature on enzymatic activity. As the optimum temperature is decreased or increased, the slope of the graph is either negatively skewed or positively skewed. Low temperatures will inactivate the enzyme whilst high temperatures would denature it. The highest rate of reaction is where the optimum temperature is reached and where the enzyme could work efficiently.

references:

David Hames, Nigel Hooper. Instant Notes in Biochemistry. New York: Taylor and Francis

Group,2005.

David L. Nelson, Michael M. Cox. Lehninger Principles of Biochemistry. New York: W. H.

Freeman and Company, 2008.

“Specificity of Enzymes,” Worthington Biochemical Cooperation, accessed April 07, 2013,

http://www.worthington-biochem.com/introbiochem/specificity.html

“ Six Types of Enzyme Catalysts,” Cliff Notes, accessed April 02, 2013,

http://www.cliffsnotes.com/study_guide/Six-Types-of-Enzyme-Catalysts.topicArticleId-   

 24998,articleId-24970.html

T. W. Graham Solomons, Craig B. Fryhle. Organic Chemistry. New Jersey: John Wiley & Sons,

2006.

“ Types of Inhibition,” NIH Chemical Genomics Center, accessed April 03, 2013,

http://assay.nih.gov/assay/index.php/Types_of_Inhibition

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One response to “Ending enzymes with an INTRO.

  1. Anonymous

    bel servizio da provare, complimenti per il blog 😉 Aspettiamo nuovi aggiornamenti al Blog !!

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