Allen sandbox 1: Difference between revisions
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'''Step 3''': An electron transfer reaction then occurs from the C'1 carboxyl oxygen to form a ketone. This removes electrons from the alkene bond between C'1 and C'2 to create an alkene between C'2 and C'3 instead. This allows the C'3 hydroxyl group to deprotonate Glu 211, resulting in the ejection of a water molecule and formation of the product PEP. PEP is then dephosphorylated in the next step of glycolysis to create pyruvate. | '''Step 3''': An electron transfer reaction then occurs from the C'1 carboxyl oxygen to form a ketone. This removes electrons from the alkene bond between C'1 and C'2 to create an alkene between C'2 and C'3 instead. This allows the C'3 hydroxyl group to deprotonate Glu 211, resulting in the ejection of a water molecule and formation of the product PEP. PEP is then dephosphorylated in the next step of glycolysis to create pyruvate. | ||
Studies have shown that mutating the residues within the active site can have serious effects on the activity of the enzyme. For example, mutation in either Glu 168, Glu 211, Lys 345, or Lys 396 of the active site results in a reduction in the reaction activity by 10^4 to 10^5 of wild type levels. Clearly, these residues play critical roles in maintaining enolase's activity.<ref></ref> | Studies have shown that mutating the residues within the active site can have serious effects on the activity of the enzyme. For example, mutation in either Glu 168, Glu 211, Lys 345, or Lys 396 of the active site results in a reduction in the reaction activity by 10^4 to 10^5 of wild type levels. Clearly, these residues play critical roles in maintaining enolase's activity.<ref>Reed, G., Poyner, R., Larsen, T., Wedekind, J., Rayment, I. (1996)''Current Opinion in Structural Biology'' '''6''':736-743</ref> | ||
Additionally, this mechanism can be inhibited by addition of Fluoride ions, which bond to Mg 2+, thus blocking the substrate (2PG) from binding to the active site of enolase.<ref>{{textbook |author=Voet, Donald; Voet, Judith C.; Pratt, Charlotte W.|title=Fundamentals of Biochemistry: Life at the Molecular Level|edition= 3|pages=500|}}</ref> | Additionally, this mechanism can be inhibited by addition of Fluoride ions, which bond to Mg 2+, thus blocking the substrate (2PG) from binding to the active site of enolase.<ref>{{textbook |author=Voet, Donald; Voet, Judith C.; Pratt, Charlotte W.|title=Fundamentals of Biochemistry: Life at the Molecular Level|edition= 3|pages=500|}}</ref> | ||
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==Kinetics== | ==Kinetics== | ||
[[Image:enolase kinetics.jpeg|left|150px|V vs. [PGA]; PGA is 2PG, the top curve has [Mg2+] of 10^-3 M and the bottom curve has [Mg2+] of 106-2 M]]<ref>{{journal2}}</ref>The kinetics of the enolase reaction can be affected by the concentration of magnesium ion, Mg2+. The graph to the left shows velocity vs. [PGA], in which PGA stands for 2-PG. The upper curve is the reaction at normal [Mg2+], 0.01 M, while the lower curve shows the same reaction at an increased concentration of [Mg2+], 0.1 M. This shows that upon addition of Mg2+, the Vmax is lowered to sub-optimal levels, while the Km remains relatively unchanged. Therefore, the upper curve (lower [Mg2+]) is more desirable because it achieves a greater Vmax without the need for additional substrate<ref>{{journal2}}</ref>. | [[Image:enolase kinetics.jpeg|left|150px|V vs. [PGA]; PGA is 2PG, the top curve has [Mg2+] of 10^-3 M and the bottom curve has [Mg2+] of 106-2 M]]<ref>{{journal2}}</ref>The kinetics of the enolase reaction can be affected by the concentration of magnesium ion, Mg2+. The graph to the left shows velocity vs. [PGA], in which PGA stands for 2-PG. The upper curve is the reaction at normal [Mg2+], 0.01 M, while the lower curve shows the same reaction at an increased concentration of [Mg2+], 0.1 M. This shows that upon addition of Mg2+, the Vmax is lowered to sub-optimal levels, while the Km remains relatively unchanged. Therefore, the upper curve (lower [Mg2+]) is more desirable because it achieves a greater Vmax at essentially the same Km value; a greater Vmax can be attained without the need for additional substrate<ref>{{journal2}}</ref>. | ||