Energy and Metabolism

ID #2339

I know that both the substrate and the enzyme have specific shape, and if they fit each other, the enzyme will catalyze the reaction. Does the process of one substrate "looking for" its enzyme or one enzyme "looking for " its substrate need force? if force is needed, what kink of force is it?

Enzymes are organic molecules that have active sites to bind the incoming substrate molecules (both acidic and basic). These active sites have specific chemical groups and shape that complement the substrate. There could be electrostatic interaction or hydrogen bonding and it entirely depends on molecules that are interacting with each other. 
There is a randomness to the enzyme and substrate finding each other. Chemical groups and proteins move randomly due Brownian motion. Brownian motion comes from the fact that there is a general tumble and movement of chemical groups and enzymes in a cell because they are floating through the liquid interior of the cell and being bumped into by other cell contents as they float. 
It is INCORRECT to think that the enzyme or substrate requires hydrolysis of a source of energy (like ATP) to be able to move. It is also INCORRECT to think that the enzyme or substrate takes one path straight to its partner (like a heat seeking missile). 
Instead, it is CORRECT to think of the enzyme like a person with their eyes shut in a dark room trying to find the light switch. The person (enzyme) will start walking in a random direction because they can't see where they are going, bumping into things along the way that will cause them to change their path until they find the substrate (light switch). Likewise a substrate locates an enzyme by essentially bumping into it and if the substrate fits the enzyme, a reaction is catalyzed. This is why you can increase the PROBABILITY of a substrate finding its enzyme by increasing the concentration of the substrate in the system. 

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