Monomeri polimeri. What is a protein? A protein is a polymer of of fixed length, composition and structure made by a combination of the 20.

Presentazione sul tema: "Monomeri polimeri. What is a protein? A protein is a polymer of of fixed length, composition and structure made by a combination of the 20."— Transcript della presentazione:

1 monomeri polimeri

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8 What is a protein? A protein is a polymer of of fixed length, composition and structure made by a combination of the 20 naturally occurring amino acids.

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14 I legami che aiutano le proteine a ripiegarsi

15 cisteine:cisteine ponti disolfuro

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17 The structure of proteins can be defined in a hierachical way Primary structure: the AA sequence (Thr-Gly-Leu-Pro-…) Secondary structure: local repetitive motifs common to most classes of protein structures Tertiary structure: the 3D arrangement of the secondary structure motifs to form a compact protein. Quaternary structure: the arrangements of several proteins units to form a functional multimeric structure. The coordinates of all the known structures of proteins can be found in the Protein Data Bank: http://www.rcsb.org/pdb

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19  -helix

20 Secondary structure. The a-helix. The a-helix is the most common secondary structure found in proteins. a-helices are stabilized by a number of factors. Very compact structure, small solvent exposed surface. Favorable dipolar interaction in the backbone. Low strain and intramolecular repulsion of backbone and side chains.

21  1998 GARLAND PUBLISHING Beta foglietto

22 Secondary structure. The  -sheet. The  -sheet is made by parallel or antiparallel extended strands connected by a network of hydrogen bonds. Parallel  -sheetAntiparallel  -sheet

23 Tertiary structure.  proteins.

24 Tertiary structure.  -barrel. Greek key motif

25 Tertiary structure. Membrane proteins.

26 Tertiary structure. DNA-binding proteins. Zn Cys The zinc finger

27 Quaternary structures. Haemoglobin HIV-1 protease K+ channel

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37 Alzheimer’s: Protein Folding gone Wrong…. An amyloid plaque in Alzheimer’s disease is a tangle of protein filaments The amyloid protein (42-43 residues) is derived by proteolytic cleavage of the amyloid precursor protein, a constituent of many healthy cells APP has a-helical conformation, while the amyloid protein can change into b-conformation forming aggregates, and plaques

38 monomeri polimeri

39 Struttura tipo di un nucleotide

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41 OH O CH 2 Sugar H H H A Nucleoside(-tide) OH NH 2 N N N N Base P O OH HO O Phosphate 2’3’ 4’ 5’ 1’ Nucleotide Nucleoside H+H+ - 2-Deossiribosio Ribosio Legame N-  glicosilico

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43 A G C U T

44 cytosine OH C NH2

45 Struttura tipo di un nucleotide

46 nucleoside AMPADPATP nucleotide H adenosina

47 Functions of nucleotides: Energy cycle Cofactors for enzymes Phosphate donors Information flow

48 8 Nucleotides Are Very Important Nucleotides have many other functions: They carry chemical energy in their easily hydrolyzed phosphoanhydride bonds.Example - ATP 2. They combine with other groups to form coenzymes.Example - coenzyme A (CoA) 3. They are used as specific signaling molecules in the cell.Example - cyclic AMP (cAMP)

49 What is ATP? An organic molecule that stores and releases chemical energy for use in body cells.

50 NTP NDP + Pi 8

51 + ATP ADP Pi

52 LA CELLULA PERSEGUE DUE OBIETTIVI FONDAMENTALI: la crescita cellulare il differenziamento cellulare In un contesto cellulare sociale, quale il tessuto e/o l’organo, i meccanismi responsabili della crescita e del differenziamento cellulare devono essere tra loro integrati e finemente regolati (omeostasi cellulare). I programmi di crescita e differenziamento cellulare sono geneticamente determinati.

53 Acidi Nucleici Gli Acidi Nucleici sono le macromolecole depositarie dell’informazione genetica. Due Tipi di Acidi Nucleici DNA → polimero di desossiribonucleotidi RNA → polimero di ribonucleotidi I Nucleotidi sono le subunità degli Acidi Nucleici

54 Il DNA è un polimero di desossiribonucleotidi

55 ribonucleotidi Il RNA è un polimero di ribonucleotidi

56 Acidi Nucleici Gli Acidi Nucleici sono polimeri di nucleotidi legati tra loro da legami fosfodiesteri tra i C 5’ e 3’