A bit more on Enzymes

As promised, here is a little more on enzymes…

Experiments have shown that if enzyme concentration is kept constant and substrate concentration increases, the velocity of an enzyme-catalyzed reaction increases only up to a maximum point. At, this point all of the enzymes that are available will be bounded to a substrate. This point is called Vmax.

Km is the concentration of substrate at half of the maximum velocity.

Km tells us a lot about an enzyme. For example:

– If Km is small, this shows that the enzyme only needs a small concentration of substrate in order to be saturated. The maximum velocity would be reached at times of low substrate concentration.

-If Km is large, a high substrate concentration is needed to achieve maximum velocity.

Competitive Inhibitor Song (in the style of Rihanna- Unfaithful)- verse and chorus

Story of my life, searching for the right,

Enzyme that fulfills my needs

Sorrow in my song,because it seems like wrong

Really loves my company

Enzyme you’re all I want

Can’t break enzyme-substrate love

But I’m gon’ have to make the substrate blue

Substrates are rolling in, but I’m gon’ have to bind again

‘Cause they can’t do what I can for you

This is the sad song of the inhibitor

and it kills me inside

to know that I’m in love with an active site,

Substrate, I know you’re crying

I don’t wanna do this anymore

I don’t wanna be the reason why

Every time I bind to you some more,

I see you die a little more inside,

I don’t wanna do this anymore

I don’t wanna have to end your life

I don’t wanna be a murderer…..

Enzymes: Biological Catalysts

A well-known definition given for enzymes in this video is that enzymes are biological catalysts that speed up the rate of a chemical reaction by providing an alternate route for the reaction, lowering the activation energy of the reactant molecules.

Interesting to note is that the enzyme not only consists of active sites but it also consists of allosteric sites, where binding can occur.

Enzymes are known to be specific for whatever reaction they catalyze and this specificity comes from the R groups of the amino acids making up the enzyme at the active site. We must remember that the enzyme is also a protein.

The binding of substrate to enzyme allows for a “conformational change” of the enzyme, which is simply a change in its shape. The amazing fact that was stated to be the reason for this change is that the enzyme does this to change the the TENSION that is given to the substrate. The enzyme pulls on the substrate and breaks it into pieces, allowing for the formation of products. The activation energy is lowered in this process.

Inhibition is a process of “turning-off” the enzyme. It may occur in the body where there is the over-production of products. The inhibitor can bind to the active site, allosteric site or both, preventing the substrate from binding. Binding to the allosteric site provides for another conformational change where the substrate cannot bind to the enzyme.

This video provided analogies that made it quite easy to understand the topic. Also, new insights were gained as to how exactly the enzyme forms products and lowers activation energy. Although enzymes get more technical with Km and Vmax, those will be reviewed in a later post. 🙂

Signing out…
ShanShan 😀