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So, in the presence of light, synthesis of food is called 'photosynthesis'. Noncyclic photophosphorylation through light-dependent reactions of photosynthesis at the thylakoid membrane. In the process of photosynthesis, the phosphorylation of ADP to form ATP using the energy of sunlight is called photophosphorylation. Cyclic ...
Dephosphorylation involves removal of the phosphate group through a hydration reaction by addition of a molecule of water and release of the original phosphate group, regenerating the hydroxyl. Both processes are reversible and either mechanism can be used to activate or deactivate a protein.
Photosystem II is present on the thylakoid membranes inside chloroplasts, the site of photosynthesis in green plants. [9] The structure of Photosystem II is remarkably similar to the bacterial reaction center, and it is theorized that they share a common ancestor. The core of Photosystem II consists of two subunits referred to as D1 and D2 ...
The cyclic light-dependent reactions occur only when the sole photosystem being used is photosystem I. Photosystem I excites electrons which then cycle from the transport protein, ferredoxin (Fd), to the cytochrome complex, b 6 f, to another transport protein, plastocyanin (Pc), and back to photosystem I. A proton gradient is created across the ...
Phosphorylation allows cells to accumulate sugars because the phosphate group prevents the molecules from diffusing back across their transporter. Phosphorylation of glucose is a key reaction in sugar metabolism. The chemical equation for the conversion of D-glucose to D-glucose-6-phosphate in the first step of glycolysis is given by:
Phosphorylation of the hydroxyl group can change the activity of the target protein, or may form part of a signaling cascade via SH2 domain binding. [10] A tyrosine residue also plays an important role in photosynthesis. In chloroplasts (photosystem II), it acts as an electron donor in the reduction of oxidized chlorophyll. In this process, it ...
Xanthophylls typically present oxygen as a hydroxyl group. Thin layer chromatography is used to separate components of a plant extract, illustrating the experiment with plant pigments that gave chromatography its name. Plant xanthophylls form the bright yellow band next to the green.
PRK catalyzes the phosphorylation of RuP into RuBP. A catalytic residue in the enzyme (i.e. aspartate in RsPRK) deprotonates the O1 hydroxyl oxygen on RuP and activates it for nucleophilic attack of the γ-phosphoryl group of ATP. [10] As the γ-phosphoryl group is transferred from ATP to RuP, its stereochemistry inverts. [12]