BIO-310
BIOCHEMISTRY II
XI. WEEK
LECTURE CONTENTS OF 11TH WEEK
• Bioenergetics I: Basic principles of
bioenergetics, free energy changes of biological
systems and factors affecting them.
Bioenergetics and introduction to oxidative phosphorylation
Bioenergetics I: Basic principles of bioenergetics, free energy changes of biological systems and factors affecting them.
Bioenergetics II: Free energy exchange and
biological importance with the hydrolysis of
ATP, other phosphorylated compounds and
their importance, functioning of oxidation-
reduction reactions, compounds and their
importance in the field.
• Bioenergetics II: Free energy exchange and
biological importance with the hydrolysis of
ATP, other phosphorylated compounds and
their importance, functioning of oxidation-
reduction reactions, compounds and their
importance in the field.
• Live cells need energy for the vital processes of the cell to maintain their regular structure, synthesize cellular components, generate electric current and so on, and they do constant work.
• In all chemical reactions, the desire to reach the
most stable bond structure (enthalpy) is the desire
to reach high disorder (entropy).
LİPPİNCOTT’S ILLUSTRATED REVİEWS: BİOCHEMİSTRY, 3RD ED. BY PAMELA C. CHAMPE AND RİCHARD A.
HARVEY, PAGE 69.
• The driving force in the reactions is the free energy exchange, which is symbolized as ΔG.
• When this value is negative and numerically large, the reaction proceeds forward.
• When this value is positive and numerically large,
the reaction tends to reverse.
• https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.slideshare.net%2Fashokktt
%2Fbiological-oxidation-bioenergetics-and-general-concepts-part-
i&psig=AOvVaw3IlWn8fQHvGw9mqhtGwOVU&ust=1587561403001000&source=images&cd=
vfe&ved=0CAIQjRxqGAoTCNDq3Z7N-egCFQAAAAAdAAAAABCzAw
• When ΔG is equal to 0, the reaction is in equilibrium.
• Free energy changes can be collected.
• The energy unit of the living cells is ATP, and the
exogenous transformation of ADP and Pi provides
many reactions.
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OVERVİEW
•
The energy from the oxidation of NADH is harvested by the electron transport chain for the production of ATP•
Electrons are passed from e.g. NADH to a final electron acceptor (e.g. O2)• Takes a convoluted path through the electron transport chain
•
Creation of a proton gradient, which is coupled to ATP synthesis• “oxidative phosphorylation” of ATP uses O2
•
Electron transport occurs at a membrane•
In eukaryotes, occurs in mitochondria• Mitochondria possess a double membrane, reaction occurs on inner membrane
• https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.slideshare.net
%2Fkhairullah127%2Fbiochemica-redox-reactions&psig=AOvVaw2ozkl-
BopwJCGPf8y0kFvM&ust=1587586418471000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCMCTu7eq- ugCFQAAAAAdAAAAABAD
• https://www.google.com/url?sa=i&url=http%3A%2F%2Fwww.bioinfo.org.cn%2Fbook%2Fbiochemistry
%2Fchapt13%2Fbio6.htm&psig=AOvVaw2ozkl-
BopwJCGPf8y0kFvM&ust=1587586418471000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCMCTu7eq- ugCFQAAAAAdAAAAABAI
• E=E˚+ RT/nƑ x ln [electron acceptor/elektron donor]
•
E=E˚+ 0,026 V / n x ln [electron acceptor/electron donor]•
ΔG'˚= -nƑ ΔE'˚•
Acetaldehyde + NADH+H+ Ethanol + NAD+•
ΔG'˚=?•
1)Acetaldehyde +2H++2e- Ethanol•
2) NAD+ 2H++2e- NADH+H+•
ΔE'˚= -0,197V-(-0,320V)=0,123 V•
ΔG'˚= -nƑ ΔE'˚ = -2(96,5 kJ/V.mol)(0,123 V)•
= - 23,7 kJ/mol• There are also molecules such as PEP, 1,3-
bisphosphoglycerate and phosphocreatine which have large and negative hydrolysis.
• Inorganic polyphosphate is the phosphoryl group storage with high group transfer potential.
• Oxidation-reduction reactions are two half
reactions with different standard reduction
potential (E’˚)
• When two electrochemical semi-cells are
combined, which involve the components of both half-reactions, the electrons tend to go to the half- cell with a high reduction potential.
• In oxidation and reduction reaction;
ΔG’˚= -nƑΔE’˚
• NAD and NADP are cofactors of most dehydrogenases.
• Both take two electrons and a proton.
• FAD and FMN serve as prosthetic groups that are firmly bound to flavopoteins.
• These are important molecules in ATP synthesis.
• DETAILED INFORMATION ON THIS SUBJECT WILL BE DISCUSSED
WITH QUESTIONS.
REFERENCES
MAIN : LEHNINGER PRINCIPLES OF BIOCHEMISTRY, DAVID L. NELSON, MICHAEL M.
COX, 5TH EDITION, 2013.
PRİNCİPLES OF BİOCHEMİSTRY, H. R. HORTON, L.
A. MORAN, K. G. SCRİMGEOUR, M. D. PERRY, J.
D. RAWN, PEARSON PRENTİS HALL, 2006.
COLOR ATLAS OF BIOCHEMISTRY, J. KOOLMAN, K. H. ROEHM, GEORG THIEME VERLAG, 2005.
HARPER’S ILLUSTRATED BIOCHEMISTRY, R. K.
MURRAY, D. K. GRANNER, P. A. MAYES, V. W.
RODWELL, LANGE MEDICAL BOOKS/MCGRAW- HILL MEDİCAL PUBLISHING DIVISION, 2003.
BASİC CONCEPTS İN BİOCHEMİSTRY, A STUDENT’S SURVİVAL GUİDE, H. F. GİLBERT, MCGRAW-HİLL HEALTH PROFFESİONS DİVİSİON, 2000.
