Structure
MPI is composed of 440 Amino Acid residues, with one active site and one zinc ion Ligand. Amino acids GLN 111A, HIS 113A, GLU 138A, HIS 285A, and HOH 798A are involved with the zinc ligand bonding. Structure differs from phosphoglucose isomerase by a threonine residue (Thr291) which creates extra space in the active site of PMI to accommodate the different stereochemistry of M6P. This increased space created by the threonine allows the rotation of the C2-C3 bond, which enables the necessary cis-enediol intermediate to be formed. Because mannose and glucose are stereoisomers at C2, which is crucial to the mechanism for both enzymes, PMI must allow extra space in the active site to allow for rotation of mannose to form the cis-enediol intermediate, which is the same intermediate formed by Phosphoglucose Isomerase.
Read more about this topic: Mannose Phosphate Isomerase
Famous quotes containing the word structure:
“I really do inhabit a system in which words are capable of shaking the entire structure of government, where words can prove mightier than ten military divisions.”
—Václav Havel (b. 1936)
“Agnosticism is a perfectly respectable and tenable philosophical position; it is not dogmatic and makes no pronouncements about the ultimate truths of the universe. It remains open to evidence and persuasion; lacking faith, it nevertheless does not deride faith. Atheism, on the other hand, is as unyielding and dogmatic about religious belief as true believers are about heathens. It tries to use reason to demolish a structure that is not built upon reason.”
—Sydney J. Harris (1917–1986)
“One theme links together these new proposals for family policy—the idea that the family is exceedingly durable. Changes in structure and function and individual roles are not to be confused with the collapse of the family. Families remain more important in the lives of children than other institutions. Family ties are stronger and more vital than many of us imagine in the perennial atmosphere of crisis surrounding the subject.”
—Joseph Featherstone (20th century)