A-ATP Synthase

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(Difference between revisions)

Revision as of 06:49, 16 November 2011

1 Introduction
2 Structure
3 Transition State Stabilization
4 Mutants

Introduction

The A1Ao ATP synthase from archaea represents a class of chimeric ATPases/synthases, whose function and general structural design share characteristics both with vacuolar V1Vo ATPases and with F1Fo ATP synthases. ^[1] A1A0 ATP synthase catalyzes the formation of the energy currency ATP by a membrane-embedded electrically-driven motor. The archaeon in this study, Pyrococcus horikoshii OT3 is an extreemophile residing in oceanic deep sea vents. ( )The membrane-embedded electrically-driven motor (A0) is very different in archaea with sometimes novel, exceptional subunit composition and coupling stoichiometries that may reflect the differences in energy-conserving mechanisms as well as adaptation to temperatures at or above 100 degrees C. ^[2]

Because some archaea are rooted close to the origin in the tree of life, these unusual mechanisms are considered to have developed very early in the history of life and, therefore, may represent first energy-conserving mechanisms.

^[3]

F-ATP is a proton gradient for prokaryotic and eukaryotic. Subunit B of F1-ATPase is involved in immobilization and polarization of a H2O molecule to facilitate nucleophilic attack at the y-phosphate of ATP.

F1---closest in structure to a DNA helices F0--- V-ATPase "at expense of ATP" pumps protons

Pyrococcus is thermophilic, optimal growth at 100degrees anaerobic peptide fermentation is the principle metabolic pathway. has NTPase

Structure

They are composed of two domains that function as a pair of rotary motors connected by a central and peripheral stalk(s). A1 domain= catalytic, water soluble conformational change from 1 subunit. A ring with 3fold symmetry of a3b3 subunits (within this domain are there 4 domains? N-terminal, non-homologous, nucleotide binding a-b, C-terminal) A0 domain = ion transduction,H+ powered flagellar motor complexes. membrane embedded ion-translocating sector. 9 subunits A3B3CDEFH2ac(x^+3) sheet-loop-helix motif of P-loop

Transition State Stabilization

Mutants

Active/Alternating Catalytic Model

The active site of B subunit is cycling between 3 states. 5 STEPS- ONE IS STANSITION STATE the deviations between the three states are concentrated within three regions… As "Open state"-ADP and Pi enter active site

(P loop farthers, s238 farthest)

Avi "loose state"-closes up around molecules and binds them loosely (transition state has more free energy than both S and P)

(P loop intermediate S238 closest G234 residue sidechain k240 P loop closer)

Apnp "tight state"- forces molecules together, binding ATP with high affinity

(P loop closest S238 int K240 significant)

possible sources of error can be the fact that ADp is not bound during transition state? is synthase reversible? where is it located? absence of ADP, may not affect the formation of transition-like state because of example reaction coordination=freeze frame picture of reactants*RELATE TO LECTURE substrates=higher free energy than products when the enzyme is complementary to the substrate, the E.S. complex is more stable, has less free energy in the ground state than substrate alone. You increase the activation energy.

Mutants

References

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Kaitlin Chase MacCulloch, Michal Harel, Alexander Berchansky

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A-ATP Synthase

From Proteopedia

Revision as of 06:49, 16 November 2011

Contents

Introduction

Structure

Transition State Stabilization

Mutants

Active/Alternating Catalytic Model

References

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@@ Line 8: / Line 8: @@
 <ref> http://www.mendeley.com/research/bioenergetics-archaea-atp-synthesis-under-harsh-environmental-conditions/ </ref>
+F-ATP is a proton gradient for prokaryotic and eukaryotic. Subunit B of F1-ATPase is involved in immobilization and polarization of a H2O molecule to facilitate nucleophilic attack at the y-phosphate of ATP.
+F1---closest in structure to a DNA helices
+F0---
+V-ATPase "at expense of ATP" pumps protons
-==Structure==
+Pyrococcus is thermophilic, optimal growth at 100degrees anaerobic peptide fermentation is the principle metabolic pathway. has NTPase
+==Structure==
+They are composed of two domains that function as a pair of rotary motors connected by a central and peripheral stalk(s).
+A1 domain= catalytic, water soluble conformational change from 1 subunit. A ring with 3fold symmetry of a3b3 subunits
+(within this domain are there 4 domains? N-terminal, non-homologous, nucleotide binding a-b, C-terminal)
+A0 domain = ion transduction,H+ powered flagellar motor complexes. membrane embedded ion-translocating sector.
+subunits A3B3CDEFH2ac(x^+3)
+sheet-loop-helix motif of P-loop
 ==Transition State Stabilization==
@@ Line 22: / Line 35: @@
-==As, Avi, and Apnp comparisons==
+==Active/Alternating Catalytic Model==
+The active site of B subunit is cycling between 3 states. 5 STEPS- ONE IS STANSITION STATE
+the deviations between the three states are concentrated within three regions…
+As     "Open state"-ADP and Pi enter active site
+(P loop farthers, s238 farthest)
+Avi    "loose state"-closes up around molecules and binds them loosely (transition state has more free energy than both S and P)
+(P loop intermediate S238 closest G234 residue sidechain k240 P loop closer)
+Apnp "tight state"- forces molecules together, binding ATP with high affinity
+ (P loop closest S238 int K240 significant)
+possible sources of error can be the fact that ADp is not bound during transition state? is synthase reversible? where is it located? absence of ADP, may not affect the formation of transition-like state because of example
+reaction coordination=freeze frame picture of reactants*RELATE TO LECTURE
+substrates=higher free energy than products
+when the enzyme is complementary to the substrate, the E.S. complex is more stable, has less free energy in the ground state than substrate alone. You increase the activation energy.