Biochemians unite!


Attack on Enzyme (Video)!!!


Reflection 5- Enzymes

u complete me

Hey people of the biochemistry and science nation. I’m Shiv Shiv and I’m here to talk about what life is without me the enzyme…I’m just kiddin. So yea enzymes, what are they?  Why do we need it? Who discovered this? So many questions to be asked I shall begin to answer them all for you.

I’ve learned that the scientist Louis Pasteur, came up with an idea that yeast converted sugar to ethanol during a fermentation reaction.  Still it wasn’t until chemist Edward Buchner proved that it wasn’t the yeast itself that caused the fermentation but the extracts, which he called zymase. This was how enzymes were found to be independent of the cell. A few decades later Jeans Sumner singled out a single enzyme molecule. Just imagine the world of opportunity and discovery which opened for Biochemistry. He called it urease which is a protein and so are the majority of enzymes. Further advancement into knowledge and technology described the enzyme as a catalyst which means that they speed up a reaction giving the constant product required without being chemically changed by the process.

Louis Pasteur- A Biochemical Pillar

Louis Pasteur- A Biochemical Pillar

Substrate is the name given to molecules in the beginning of enzymatic reaction and upon enzyme activity they are converted to products. The number of substrate molecules converted to the product in an enzyme molecule per second is called Kcat (Benjamin et al., 1997). The method of decreasing the activation energy is to speed up the overall reaction rate to form products and acquire equilibrium at a hastened paste. Oh! Just in case you didn’t know, the energy required to complete a chemical reaction is called the activation energy. In the reaction, only the time taken to complete the process changes as everything else remains constant. Proteins and sometimes RNA make up the structure of an enzyme in globular form as a tertiary or quaternary structure. Each enzyme reacts specifically with a substrate because of its hydrophobic and hydrophilic characteristics.  The active site is a indent or cleft in an enzyme where the substrate binds with it. The combined structure of the enzyme and the substrate form the enzyme-substrate-complex. These characteristics are like the makers of the active site they move according to the surroundings forming certain structures that can only accept specific substrates; this shows that active sites of enzymes are specific to certain substrates.

Basic Energy Profile Diagram illustrating the effects of enzyme activity

Basic Energy Profile Diagram illustrating the effects of enzyme activity

Specificity of enzymes is due to the shape and size of the active site.  An enzyme may have the induced fit or lock and key method. The lock and key method was 1st postulated by Emil Fisher who I thank very much for having this part of biochemistry unlocked, as this indicated the specificity of the enzyme because the theory suggested that the enzyme has a certain shape that only some or a specific substrate may enter to react with the enzyme. The induced theory however, stated that an enzyme can stretch and be flexible to facilitate a substrate as long as it is compatible with the enzyme. Enzyme react in catabolic and anabolic phases. Catabolic reactions break down and release energy to drive a chemical reaction, this same energy is used in anabolic reactions to build , make new molecules and store energy.I got a wonderful illustration below to show to you!



Lock and key versions of catabolic and anabolic reactions

Lock and key versions of catabolic and anabolic reactions

Thousands of enzymes within the body are essential for an organism to survive and function properly. Some enzymes may not function without the aid of a nonprotein chemical component. The compound is known as a cofactor. Okay let’s not forget enzymes and inhibition, there irreversible inhibition and reversible inhibition. They can be told apart by the individual attraction for an enzyme. An irreversible inhibitor is formed where the bonds from the enzyme are “tougher than concrete”, making it hard to break apart permanently removing catalytic activity. This type of inhibitor is also called inactivators and can bond covalently to amino acids during catalysis in the active site. Allosteric site is a site on the enzyme that would allow another molecule to bind with it. The enzyme becomes unfit for substrates to bond with it. Inhibition can also be reversible, where the inhibitor forms a weak bond with the enzyme so it is easier to break apart to allow for a substrate to come back. There are four types of reversible inhibitions; they are: competitive, uncompetitive inhibition, mixed inhibition and non competitive inhibition. Competitive inhibition is where an inhibitor competes with a substrate to bond with an enzyme to inhibit its catalytic function. Non-competitive inhibition is where an inhibitor bonds permanently with the enzyme blocking all its enzymatic functions.   The inhibitors main function is to decrease the enzymes ability to work on a substrate and lower the catalytic ability.

Lets focus a bit on competitive inhibition which can be illustrated in the Line-Weaver Burk plot below. In enzymology, when initial velocity of a reaction is plotted against substrate concentration, it is sometimes not possible to determine Vmax immediately. By reciprocating both values, the resulting Lineweaver Burk plot can be used as a graphical apparatus to observe mechanisms of inhibition.

A competitive inhibition Line-weaver Burk plot

A competitive inhibition Line-weaver Burk plot

The plot suggests that the effect of the inhibitor can be reversed by increasing substrate concentration since Vmax is constant. Furthermore, Km was seen to have increased(with inhibitor concentration) which implies that more substrate is required to achieve 1/2 Vmax (Substrate affinity decrease with the inhibitor).


The concentration of a substrate and enzyme can affect the rate of reaction, by increasing its concentration present in the reaction, it will cause an increase in the reaction. If at one point the substrate remains constant and the concentration of enzymes increase then the rate increases linearly. When substrate concentration increases the rate of reaction will only increase for a certain period where it levels out and remains constant. At this point the enzymes can no longer increase in catalytic function and a line parallel to the x axis on the graph is formed, this is what is known as linearly increasing. Two other factors that affect the rate of reaction are the temperature and effect of pH.  These can only positively affect the rate at their optimum levels.  Any higher and denaturation begins, denaturation is the loss of catalytic function in an enzyme .Heat above 40 degrees Celsius along with strong acids or bases and  inorganic salts in high concentration causes denaturation of enzymes.


The effect of substrate concentration annotated graphically.

The effect of substrate concentration annotated graphically.

The effect of temperature on enzyme reaction

The effect of temperature on human enzyme reaction

The effect of pH on enzyme catalyzed reaction

The effect of pH on enzyme catalyzed reaction

Enzymes are used in digestion of food and metabolic enzymes. Food enzymes are found in… you guessed it food. It is also used for digestion in the digestive system and metabolic throughout the body. From food we can trace backward to how food is made and it is mostly from plants. Enzymes have been modified and used as fertilizers, pest control and additives for improvement of digestion in livestock. This is amazing for me to know that enzymes are so essential in the way man altered it to be used for protection of resources. The soil, water and quality of the goods produced are extremely upgraded after treatment of enzymes. Dry barren soil can be turned into rich vegetative soil just as plants can bear faster and bigger than without enzyme treatment to it. Interesting huh? Well I hope this was informative and that something that I talked about remains with you after reading this blog entry! Now it’s time for me to go… Look forward to Richie’s reflection on GLYCOLYSIS!!! Shiv Shiv over and out!!!

keep calm


Ramersar, Myda, Mary Jones, Geoff Jones. 2011. Biology for CAPE.

Picture References:

Louis Pasteur-

Activation energy-

Enzyme Activity process-

Line weaver-

substrate concentration-

effect of temperature on enzyme

enzyme ph-

keep calm-

You complete me-

Word Search- Enzymes Galore! done by Reshi

Word Search- Enzyme

Hey everyone! Just wanted to wish you guys a safe Carnival 2014! Even though we are on a bit of a holiday right now, I’ve spent today listening to some enzyme videos and a few key words caught my attention. So I decided to put them into a word search! Some of these terms were familiar to me, while some were quite foreign. So just for some general knowledge, I’ve defined a couple of new terms below:

Transition state – this can be seen as the intermediate structure in a reaction, where it is a merge between the structures of the reactants and products.

Cofactor – this is the non-protein part of an enzyme. It can be divided into two types; inorganic cofactors and organic cofactors. Inorganic cofactors are usually metal ions e.g. Zn2+, whereas organic cofactors are normally derived from vitamins, or are vitamins themselves.

Apoenzyme– this is an inactive protein component of an enzyme. This is where the cofactor attaches to activate the enzyme.

Holoenzyme– this is an active enzyme that is made up of an apoenzyme and a cofactor.