BIOTIN SUPPLEMENTS

CLAIMS:
Aids in Carbohydrate, fat and protein metabolism.

BIOCHEMISTRY BEHIND THE CLAIM
A cofactor in is any substance other than the substrate that is needed for the activity of an enzyme. Biotin is the cofactor of carboxylase enzymes. Since the manufacturers of the biotin supplement claim that it aids in carbohydrate, fat and protein metabolism, we need to look at carboxylase mediated reactions in these metabolic processes.

CARBOHYDRATE METABOLISM
We can find the carboxylase enzyme in the first bypass reaction of Gluconeogenesis. This reaction is
Pyruvate + CO2 + ATP —> Oxaloacetate + ADP +Pi
The enzyme that catalyses this reaction is Pyruvate carboxylase and of course, its cofactor is biotin.
Gluconeogenesis which takes place in the liver is needed in the fasting state to produce glucose. All the enzymes of gluconeogenesis are the same as glycolysis except for four of them which are Pyruvate carboxylase and phosphoenolpyruvate carboxykinase which part take in the first bypass reaction, Fructose – 1, 6 – bisphosphatase which part takes in the second bypass reaction and glucose – 6- phosphatase which takes part in the third bypass reaction. So as we can see, biotin is needed for the pyruvate carboxylase in the first bypass reaction or gluconeogenesis cannot take place. The claim that biotin supplements aid in carbohydrate metabolism is true.

FAT METABOLISM
Again, we find the carboxylase enzyme in the committed step of fatty acid synthesis. The reaction is
Acetyl CoA + CO2 + ATP —> Malonyl CoA + ADP +Pi
The enzyme that catalyses this reaction is Acetyl CoA carboxylase and biotin is the cofactor. Fatty acid synthesis which takes place in the liver is needed in the fed state when we have excess carbohydrates in our bodies. In the well fed state, the energy requirements of the body is met so we do not need Acetyl CoA to enter the Krebs cycle. In this case, Acetyl CoA is converted to citrate and leaves the cell where is converted back to acetyl CoA. Acetyl CoA can be used in the Krebs cycle and fatty acid synthesis but because we are in the fed state, we need to commit the Acetyl CoA to fatty acid synthesis. To do this, we use the enzyme Acetyl CoA carboxylase to convert Acetyl CoA to Malonyl CoA. As we know, biotin is the cofactor of this enzyme so the claim that biotin aids in fat metabolism is true.

PROTEIN METABOLISM
We find the carboxylase enzyme in the breakdown of amino acids like leucine, isoleucine and valine. The enzyme used is Beta-methylcrotonyl-CoA carboxylase. This enzyme converts these amino acids to ketone body precursors like HMG CoA. Carboxylase enzymes namely Propionyl CoA carboxylase is also used for the conversion of Propionyl CoA to Succinyl CoA which is a Krebs cycle intermediate.

 

References

Wikipedia,. 2014. ‘Biotin’. http://en.wikipedia.org/wiki/Biotin.

Wikipedia,. 2014. ‘Isoleucine’. http://en.wikipedia.org/wiki/Isoleucine#Biosynthesis.

Wikipedia,. 2014. ‘Propionyl-Coa Carboxylase’. http://en.wikipedia.org/wiki/Propionyl-CoA_carboxylase.

N-Zymez homie!

What the heck are enzymes?

You don’t know what enzymes are? Really?! Ok that’s fine. An enzyme is simply a biological catalyst. It speeds up a biological reaction with out being used or changed and it is specific, meaning each enzyme only works on a specific substrate. For example lipase hydrolyses lipids and only lipids. (How do enzymes speed up reactions though? ) OMG glad you asked! They just create a different pathway that has lower activation energy than the original pathway.

Most enzymes are proteins, some are RNA molecules known as ribozymes (they satisfy mostly all of the enzymatic criteria eg. they are substrate specific, they speed up the reaction rate, and they remain unchanged after the reaction. Some antibodies have catalytic properties and these are called abzymes.

What’s the big deal about enzymes?

Without enzymes life is literally impossible! Enzymes allow for respiration to occur. Which means, no enzymes à no energy à no life. Thank goodness for enzymes right? Yeah… trust me I know.

According to Ask.com, in the human body approximately 2700 enzymes can be found. These enzymes are separated into three major groups, which are: metabolic enzymes, food enzymes and digestive enzymes. Their location in the body depends on their function. Enzymes can be found in the mouth in saliva, in the stomach and everywhere else in the body. Without enzymes we are nothing!

This is an energy profile diagram.

This diagram shows exactly how enzymes speed up the reaction to produce product.

But what is activation energy? Activation energy is the minimum energy needed for a reactant to react.

How do enzymes get their name?

Um… their parents obviously name them at birth just like everyone else! No, just kidding. Enzymes are either named based on the substrate they react on, the action they perform, they end in ‘ase’ or they just have some random name that has nothing to do with them. Because names were getting out of hand, our homies at The International Union of Biochemistry and Molecular Biology, IUBMB for short, decided to come up with a naming system. They divided the enzymes into 6 classes. In each class is a sub class and in each subclass there is a sub-subclass. Each is numbered and therefore a series of 4 numbers specifies a specific enzyme (this is called the Enzyme Commission [E.C.] number.

The 6 major classes are: 

1. Oxidoreductases – Catalyze oxidation-reduction reactions
2. Transferases – Catalyze the transfer of C,N or P containing groups
3. Hydrolases – Catalyze cleavage of onds by adding water.
4. Lyases – Catalyze clevage of C-C, C-S an some C-N bonds
5. Isomerases – Catalyze isomerizaton of optical or geometric bonds
6. Ligases – Catalyze the formation of bonds between C and O, S, and N couples to hydrolysis of high energy phosphates.

Holoenzyme?? Hol up.. holo what??

Omg chillllll! Its simple! A holoenzyme is just a biochemical compound that is a combination of an enzyme and a coenzyme. And before you go a-wall!  A coenzyme is just a substance that is necessary for an enzyme to function.

Inorganic Catalyst v.s Biological Catalyst

Well incase you didn’t know, biological catalyst are THEE (emphasis on thee) fastest by far when compared to inorganic ones. Biological catalysts are also the most efficient. For example: during the Haber process, which makes ammonia, the temperature needed is 450 degree Celsius, at 1000 atm! What? Amylase breaks down starch to maltose in my mouth and at less than 100 degrees Celsius! And unless you’re a fire-breathing dragon it does the same for you!

So whenever you’re feeling on top of the world, and feel that you can take on a lion, tiger or bear… give enzymes a quick shout out, because with them my good friend… you are without life.

Here’s some pickup lines! Use them wisely.

In that order!

Chao for now!