The enzyme ribulose bisphosphate carboxylase/oxygenaseis (Rubisco) is the most abundant enzyme on Earth and is essentially the most important. It is known as the “carbon fixer”. Carbon is essential for all life, however it is locked in oxidized forms in the atmosphere and earth, such as carbon dioxide or carbonate minerals. This oxidized carbon must be "fixed" into more organic forms to be useful for organisms. Commonly found in plants, Rubisco creates organic carbon from the inorganic carbon dioxide in the air with the help of sunlight. This central task of carbon fixation is known as photosynthesis in plants. It is a very important enzyme and is essential for the carbon cycle. Even though this enzyme has such a central importance, it is inefficient because it works very slowly compared to other enzymes. Plant cells compensate for this slow rate by producing lots of the enzyme. Chloroplasts are filled with Rubisco, which makes it the most plentiful enzyme on Earth.
Rubisco takes carbon dioxide from the air and attaches it to ribulose biphosphate, a short sugar chain with five carbon atoms. This six-carbon molecule is extremely unstable and rubisco immediately clips the lengthened chain into two identical phosphoglycerate pieces, each with three carbon atoms. Most of the phosphoglycerate made by rubisco is recycled to build more ribulose bisphosphate, while some is skimmed off to make sucrose and feed the rest of the plant. The 3-phosphoglycerate can be used to produce larger molecules such as glucose.
During the night, the Rubisco active sites are blocked by inhibitors or misfired reactants, which ensures that it will only be active during the day when sunlight is available. The active site of Rubisco is centered around a magnesium ion. The magnesium ion is free to bind to both ribulose bisphosphate, holding onto two oxygen atoms, and the carbon dioxide molecule that will be attached to sugar. Because Rubisco may lack some specificity, Rubisco may attach an oxygen molecule instead of the carbon dioxide molecule to the sugar chain, forming a faulty oxygenated product and will have to go through a series of reactions to correct the mistake.
This is the overview of the protein Rubisco. This shows two copies of the large chain and you can also see the active sites. The alpha-helixes and beta-pleated sheets are clearly visible.
This is an image of ribulose biphosphate, a short sugar chain with five carbon atoms. A carbon dioxide molecule will be binded to this sugar.
This is an image of the magnesium atom in the center of the active site. It is binded to the five carbon sugar pictured above.
This is a picture of the magnesium atom about to bind the carbon dioxide molecule to the five carbon sugar. The addition of this carbon dioxide molecule will cause the newly formed 6 carbon molecule to break down into two identical 3-phosphoglycerate pieces.
It was interesting to know that the active sites are closed during the night. Everything was thoroughly explained especially how the protein functioned. It was very easy to understand even though it is a complicated process.
ReplyDeleteThank you, I thought it was important to add that it was closed during the night to show when photosynthesis occurs.
DeleteResearch and writing was well done. Image two's importance could have been elaborated on. Besides that everything is great.
ReplyDeleteThank you, I tried to elaborate as much as I could to help people understand the screenshots.
DeleteExplanation of how magnesium plays a key role in binding carbon dioxide with the 5 carbon sugar along with the last 2 screenshots were very good. The structures, functions and the protein's role in converting carbon dioxide into organic form was explained elaborately.
ReplyDeleteThank you, I tried to make my screenshots relevant to the active site to better explain the role of my enzyme.
DeleteI liked how you have a little bit of background of your protein in the beginning. Also you had a lot of important information about your protein made your post even better. The simple explanations of the pictures were easy to follow.
ReplyDeleteGood project I like the explanation in the beginning and your pictures they help me gain an understanding the protein. I also agree with Connor for picture 2 if you explained the picture a little bit more. If you stated what would happen once they would bind would be a good thing to add. But overall I like it.
ReplyDeleteI just have one question. In the introduction of the post you talk about how the rubisco creates organic carbon from inorganic carbon. I was just wondering what you meant by "organic". I know in chemistry organic means things containing carbon and inorganic would be things without carbon. But the article was great though. It was easy to understand and interesting.
ReplyDelete