Pyruvate phosphate dikinase: Difference between revisions
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PPDK assembles into homodimers of ~95 kD subunit molecular mass. The monomer is comprised of three domains and contains two distinct reaction centers located ~45 Å apart; the PEP/pyruvate partial reaction (step 1) takes place at the C-terminal domain (adopting an α/β barrel fold) and the nucleotide and inorganic phosphate partial reactions (steps 2 and 3) take place at the N-terminal domain (adopting the ATP grasp fold with two sub domains). A central domain, tethered to the N- and C-terminal domains by two closely-associated linkers, contains a phosphorylatable histidine residue (His455). To shuttle the phosphoryl group between the two reaction centers, the His-domain undergoes domain motion of ~110° swivel around the two linkers. In addition, upon detachment from the His-domain, the two nucleotide-binding sub domains undergo a ~40° hinge motion that opens the active site cleft. | PPDK assembles into homodimers of ~95 kD subunit molecular mass. The monomer is comprised of three domains and contains two distinct reaction centers located ~45 Å apart; the PEP/pyruvate partial reaction (step 1) takes place at the C-terminal domain (adopting an α/β barrel fold) and the nucleotide and inorganic phosphate partial reactions (steps 2 and 3) take place at the N-terminal domain (adopting the ATP grasp fold with two sub domains). A central domain, tethered to the N- and C-terminal domains by two closely-associated linkers, contains a phosphorylatable histidine residue (His455). To shuttle the phosphoryl group between the two reaction centers, the His-domain undergoes domain motion of ~110° swivel around the two linkers. In addition, upon detachment from the His-domain, the two nucleotide-binding sub domains undergo a ~40° hinge motion that opens the active site cleft. | ||
'''The His-domain in the two conformational states of PPDK. His455 is shown in blue spheres:'''[[Image:two_cond.jpg| | '''The His-domain in the two conformational states of PPDK. His455 is shown in blue spheres:'''[[Image:two_cond.jpg|center|700px]]<br><br><br> | ||
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