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| {{STRUCTURE_1ig0| PDB=1ig0 | SCENE= }} | | {{STRUCTURE_1ig0| PDB=1ig0 | SCENE= }} |
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| '''Crystal Structure of yeast Thiamin Pyrophosphokinase'''
| | ===Crystal Structure of yeast Thiamin Pyrophosphokinase=== |
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| ==Overview==
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| BACKGROUND: Thiamin pyrophosphokinase (TPK) catalyzes the transfer of a pyrophosphate group from ATP to vitamin B1 (thiamin) to form the coenzyme thiamin pyrophosphate (TPP). Thus, TPK is important for the formation of a coenzyme required for central metabolic functions. TPK has no sequence homologs in the PDB and functions by an unknown mechanism. The TPK structure has been determined as a significant step toward elucidating its catalytic action. RESULTS: The crystal structure of Saccharomyces cerevisiae TPK complexed with thiamin has been determined at 1.8 A resolution. TPK is a homodimer, and each subunit consists of two domains. One domain resembles a Rossman fold with four alpha helices on each side of a 6 strand parallel beta sheet. The other domain has one 4 strand and one 6 strand antiparallel beta sheet, which form a flattened sandwich structure containing a jelly-roll topology. The active site is located in a cleft at the dimer interface and is formed from residues from domains of both subunits. The TPK dimer contains two compound active sites at the subunit interface. CONCLUSIONS: The structure of TPK with one substrate bound identifies the location of the thiamin binding site and probable catalytic residues. The structure also suggests a likely binding site for ATP. These findings are further supported by TPK sequence homologies. Although possessing no significant sequence homology with other pyrophospokinases, thiamin pyrophosphokinase may operate by a mechanism of pyrophosphoryl transfer similar to those described for pyrophosphokinases functioning in nucleotide biosynthesis.
| | The line below this paragraph, {{ABSTRACT_PUBMED_11435118}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 11435118 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_11435118}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Compound active site]] | | [[Category: Compound active site]] |
| [[Category: Protein-substrate complex]] | | [[Category: Protein-substrate complex]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 19:57:34 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 10:55:49 2008'' |
