The course of Biochemistry aims to provide to the students the basis to understanding the physical, chemical and biological contexts in which molecules, reactions and metabolic pathways play their role. Particular attention will be given to the structure and function relationship of the major classes of macromolecules as also to the metabolic regulation at the molecular and cellular level. In order to stimulate student interest the topics will be explained emphasizing the logical and consequential interconnections enphasizing the clinical aspects and introducing experimental methods. At the end of the present course the student will understand the structure-function relationships of the main biological molecules, essential biochemical mechanisms that underlie a proper metabolic function and the consequences of their alterations.
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PROTEIN STRUCTURE.
Structure, classification and general properties of amino acids.
Peptide bond. Definition of the primary structure, secondary, tertiary, quaternary. Angles phi, psi, chi, omega. Ramachandran plot. Secondary structure: alpha-helix, beta-strand, beta sheets (parallel, antiparallel, mixed). Reverse turn. Supersecondary structures. Definition of protein domain. The bonds that stabilize the tertiary structure of proteins. Fibrous proteins and globular proteins. Structural
classification of proteins. Fibrous proteins: keratin, silk fibroin, collagen, elastin. Collagen: primary structure, secondary structure (triple helix); synthesis and post-translational modifications (hydroxylation of proline and lysine, and the role of ascorbic acid, glycosylation, processing of pro-collagen; oxidation of lysine and formation of crosslinks).
Membrane proteins.
Folding and denaturation of proteins. Protein misfolding and human diseases.
Porphyrins and heme. Structure of myoglobin, hemoglobin and globin chains. Classification of globin chains. Saturation curve with oxygen in hemoglobin and myoglobin. Hemoglobin as allosteric protein. Oxyhemoglobin and deoxyhemoglobin structure. Bohr effect, 2.3 BPG. Hemoglobin and CO2. Hemoglobin and acid-base balance. Fetal hemoglobin. Molecular basis of hemoglobinopathies and thalassemias.
Fundamental principles of the techniques for protein purification and assay (precipitation, chromatography, electrophoresis, ultracentrifugation, immunoassays).
Basic principles of the techniques for sequencing and for the determination of the three-dimensional structure (X-ray crystallography, NMR) of proteins.
MITOCHONDRIAL BIOENERGETICS
Principles of chemical thermodynamics; ATP and high energy compounds; Role of ATP in bioenergetics. Relationship between variation of the standard free energy and standard redox potential.
Pyridin-nucleotide coenzymes: NAD and NADP; structure and function; nicotinic acid and nicotinamide (vitamin PP).
Mitochondrial electron transport chain: inner and outer mitochondrial membrane; standard redox potential of the components of the electron transport chain. Organization of the electron transport chain in the inner membrane lipoprotein complexes (complex I - II - III - IV) and mobile carriers (ubiquinone and cytochrome C). Flavin coenzymes (structure and function, FMN and FAD, riboflavin or vitamin B2); Iron-sulfur proteins; Structure and function of cytochromes. Structure and functions of Complex I (NADH-ubiquinone oxidoreductase), complex II (succinate-ubiquinone oxidoreductase), complex III (ubiquinol-cytochrome c oxidoreductase), complex IV (cytochrome oxidase). Inhibitors of electron transport.
Oxidative phosphorylation: mitochondrial ATP synthase (complex V): structure and function of the factors F1 and F0, P/O ratio; chemiosmotic coupling hypothesis, electrochemical proton gradient, respiratory control; uncoupling. Thermogenin and brown adipose tissue.
METABOLIC BIOCHEMISTRY
Vitamins and coenzymes.
Thiamine, riboflavin, pyridoxine, nicotinamide, pantothenic acid, coenzyme A, biotin, folic acid, retinol, calciferol, ascorbic acid, vitamin B12 functions
Glucidic metabolism
Biological importance of carbohydrates: glycogen, starch, disaccharides,
monosaccharides.
Aerobic glycolysis and anaerobic: chemical reactions, enzymes and functional significance. Origin of lactic acid and lactate dehydrogenase (LDH). Alcoholic fermentation. Energy balance of glycolysis.
Oxidative decarboxylation of pyruvic acid.
The citric acid cycle or Krebs cycle: reactions and energy balance. Mitochondrial localization of enzymes.
Glycogen synthesis and glycogenolysis. Regulation of the metabolism of the liver and muscle glycogen.
Gluconeogenesis.
Mechanism of action of adrenaline, glucagon and insulin.
Metabolism of fructose, lactose and galactose.
Pentose pathway: role of NADPH in metabolism. Favism. Other mechanisms for NADP reduction (malic enzyme and transhydrogenase).
1.Nelson Cox. I principi di Biochimica di Lehninger. Zanichelli
2. Siliprandi-Tettamanti. Biochimica Medica. Piccin.
3. Devlin. Biochimica con aspetti clinici. EdiSES