Enolase: Diferenzas entre revisións

Usando sondas isotópicas, o mecanismo global proposto para converter o 2-PG en PEP é unha [[E1cb|reacción de eliminación E1cb]] na que está implicado un intermediato [[carbanión]].<ref>{{cite journal |author=Dinovo EC, Boyer PD |title=Isotopic probes of the enolase reaction mechanism |journal=J Biol Chem |volume=240 |issue= |pages=4586–93 |year=1971}}</ref> O seguinte mecanismo detallado está baseado en estudos da estrutura cristalina e cinética.<ref name=Pancholi/><ref>{{cite journal |author=Poyner RR, Laughlin LT, Sowa GA, Reed GH |title=Toward identification of acid/base catalysts in the active site of enolase: comparison of the properties of K345A, E168Q, and E211Q variants |journal=Biochemistry |volume=35 |issue=5 |pages=1692–9 |year=1996 |month= February|pmid=8634301 |doi=10.1021/bi952186y }}</ref><ref>{{cite journal |author=Reed GH, Poyner RR, Larsen TM, Wedekind JE, Rayment I |title=Structural and mechanistic studies of enolase |journal=Current Opinion in Structural Biology |volume=6 |issue=6 |pages=736–43 |year=1996 |month= December|pmid=8994873 |url=http://linkinghub.elsevier.com/retrieve/pii/S0959-440X(96)80002-9 |doi=10.1016/S0959-440X(96)80002-9}}</ref><ref>{{cite journal |author=Wedekind JE, Reed GH, Rayment I |title=Octahedral coordination at the high-affinity metal site in enolase: crystallographic analysis of the MgII—enzyme complex from yeast at 1.9 Å resolution |journal=Biochemistry |volume=34 |issue=13 |pages=4325–30 |year=1995 |month= April|pmid=7703246 |doi=10.1021/bi00013a022 }}</ref><ref>{{cite journal |author=Wedekind JE, Poyner RR, Reed GH, Rayment I |title=Chelation of serine 39 to Mg2+ latches a gate at the active site of enolase: structure of the bis(Mg2+) complex of yeast enolase and the intermediate analog phosphonoacetohydroxamate at 2.1-Å resolution |journal=Biochemistry |volume=33 |issue=31 |pages=9333–42 |year=1994 |month= August|pmid=8049235 |doi=10.1021/bi00197a038 }}</ref><ref>{{cite journal |author=Larsen TM, Wedekind JE, Rayment I, Reed GH |title=A carboxylate oxygen of the substrate bridges the magnesium ions at the active site of enolase: structure of the yeast enzyme complexed with the equilibrium mixture of 2-phosphoglycerate and phosphoenolpyruvate at 1.8 Å resolution |journal=Biochemistry |volume=35 |issue=14 |pages=4349–58 |year=1996 |month= April|pmid=8605183 |doi=10.1021/bi952859c }}</ref><ref>{{cite journal |author=Duquerroy S, Camus C, Janin J |title=X-ray structure and catalytic mechanism of lobster enolase |journal=Biochemistry |volume=34 |issue=39 |pages=12513–23 |year=1995 |month= October|pmid=7547999 |doi=10.1021/bi00039a005 }}</ref> Cando o substrato 2-fosfoglicerato se une á α-enolase, o seu grupo [[carboxilo]] coordínase con dous cofactores ións magnesio no sitio activo. Isto estabiliza a carga negativa no oxíxeno desprotonado á vez que incrementa a acidez do hidróxeno alfa. A Lys³⁴⁵ da enolase desprotona o hidróxeno alfa, e a carga negativa resultante é estabilizada por resonancia co oxíxeno do carboxilato e polos cofactores Mg²⁺. Despois da creación do intermediato carbanión, o OH de C3 é eliminado como auga coa axuda do Glu²¹¹, e fórmase o PEP.

 

 

==Uso diagnóstico==