Replication enzymes have large structures, with separate subunits for different activities. Repair enzymes have much simpler structures.

TLS Online TPP Program

#Id: 9026

#Unit 6. System Physiology – Plant

Trx regulates plastid phosphoribulokinase (PRK) and NADP–glyceraldehyde-3‐phosphate dehydrogenase (NADP–GAPD) by noncovalent associations with the nuclear‐encoded chloroplast protein CP12 (an ≈8.5‐kDa protein)

TLS Online TPP Program

#Id: 9027

#Unit 6. System Physiology – Plant

TLS Online TPP Program

#Id: 9028

#Unit 6. System Physiology – Plant

Under ‘‘dark conditions,” the [(A4-glyceraldehyde-3-phosphate dehydrogenase) 2•(phosphoribulokinase)2•(CP12)4] is formed by CP12 called supramolecular complex.

TLS Online TPP Program

#Id: 9029

#Unit 6. System Physiology – Plant

Under ‘‘light conditions,’’ reduced thioredoxin cleaves the disulfide bonds of CP12 and phosphoribulokinase. 

The reduction of phosphoribulokinase and CP12 separates the

components of the ternary complex releasing the active phosphoribulokinase and the active A4B4-glyceraldehyde 3-phosphate dehydrogenase.

TLS Online TPP Program

#Id: 9030

#Unit 6. System Physiology – Plant

TLS Online TPP Program

#Id: 9031

#Unit 6. System Physiology – Plant

Stromal pH and Mg2+ concentration complement the ferredoxin– thioredoxin system and are important for the activation and maximum catalysis of enzymes such as Rubisco, fructose‐1,6‐ bisphosphatase, sedoheptulose‐1,7‐bisphosphatase, and PRK.