Why does RuBisCo have oxygenase activity ?


While studying the dual nature of RuBisCo (If you haven't yet click here which will take you to my article), you know it plays a role in carboxylation and oxgenation. Ever thought why does it exactly have the oxygenase activity ? Without wasting anymore time lets get into the topic.

Why does RuBisCo have oxygenase activity ?

RuBisCO is the first step for carbon fixation and when oxgenation takes place the first intermediate product formed in the photorespiratory pathway is phosophoglycolate, but why is it so important to produce phosphoglycolate ?

Think about the word "phosophoglycolate", if you look at it clearly you can see two words which are "phospo" which will obviously be "phosphate" and the other word "glycolate". Thus form here we can conclude that, the intermediate product is 2-phosphogylcolate and it catalyses the conversion of 2-phosphoglycolate to phosphate and glycolate.

Phosphoglycolate is an inhibitor of phosphofructokinase and triosephosphate, it must be quickly metabolized into a useful substrate.

What is RuBisCo ?

For all those who don't know what RuBisCo is as I mentioned above RuBisCo stands for Ribulose Biphosphate Carboxylase Oxygenase. It can also be termed as RubiscorubiscoRuBPCase or even RuBPco, so don't get confused when you see these terms.

RuBisCo is an enzyme which is the first product evolved in the Calvin cycle, in carbon fixation and then oxygenation takes place and photorespiration occurs. This is the main enzyme in Calvin cycle. This enzyme is available in large quantity on earth. The role of RuBisCo depends upon how much is the concentration of COand Oin the mesophyll cellsIf the concentration of CO2 is high then PGA (Phosoglyceric acid) is formed and if the concentration of Ois high, phosphoglucolic acid is formed. This effect is called the Warbug effect.

Here is a simple image you can refer to for better understanding:

 

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