Frederick sanger 1918
1 / 81

Frederick SANGER (1918-) - PowerPoint PPT Presentation

  • Uploaded on
  • Presentation posted in: General

1958 Nobel Prize in Chemistry: for his work on the structure of proteins, especially that of insulin. GIVEQCCASVCSLYQLENYCN PVNQHLCGSHLVEALYLVCGERGFFYTPKA. Frederick SANGER (1918-).

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

Frederick SANGER (1918-)

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

1958 Nobel Prize in Chemistry:for his work on the structure of proteins,especially that of insulin


Frederick SANGER(1918-)

1980 Nobel Prize in Chemistry (1/4):for his contribution concerning thedetermination of base sequencesin nucleic acids

Protein sequencing

  • Edman degradationup to ~20-30 residues, time consuming,needs large amount of purified protein

  • Recombinant DNA technologyfast, but it does not consider splicing andposttranslational modifications

  • Mass Spectrometrynot for exact sequencing of long chains, rather for cataloging of cellular proteins

Edman degradation of oligopeptidesTheory of automatic sequencing

Liquid chromatogram of the PTH derivatives of 20 amino acids

Derivatives ofdifferent aminoacids can be distinguished AND identified bytheir elution times.

Possible problems with Edman degradation:

- multiple peptide chains:the primary result of sequencing of the native protein consisting ofn peptide chains would be n amino acids for each positionin the sequence  it is impossible to decide which amino acid follows which

- imperfection (<100% efficiency):

if cleavage is performed with 95% OR 99% efficiency, the result ofstep 1:100% R1100% R1step 2:95% R2 + 5% R199% R2 + 1% R1step 10:63% R10 + 30% R991% R10 + 8% R9step 20:38% R20 + 38% R19 + 18% R1883% R20 + 16% R19step 50:8% R50 + 21% R49 + 26% R4861% R50 + 30% R49 + 7% R48

Irreversible cleavage of cystine bridges

  • Recombinant DNA technologythe human genome is “known”and the DNAamino acid dictionary is known, too

However,the encoded, the nascent and the nativesequences are NOT necessarily the same


some uncertainty

some uncertainty


some uncertainty

…and this is what we wouldlike to figure out...

Nobel Prize inChemistry2002(1/4 - 1/4)

John B. FENN


for their development of soft desorption ionisation methods formass spectrometric analyses of biological macromolecules


Matrix AssistedLaser DesorptionIonization -

Time Of FlightMass Spectrometer

ESI MS: ElectroSpray Ionization Mass Spectrometer

MS-MS or Tandem Mass Spectrometry

  • What can amino acid sequence be used for?

  • Searching for similarities by comparison to known sequences classification among protein types (FUNCTION)

  • Searching for similarities by comparison to other species evolutionary consequences can be drawn

  • Searching for internal repeats history of an individual protein

  • Searching for signals designating destination or process control  fate of the protein between translation and native state

  • Sequence data basis for preparing antibodies specific to the protein

  • Sequence data  reverse genetics:making DNA probes for the genes encoding the proteins

  • Sequence data  structures of higher order

Robert Bruce MERRIFIELD1984, Nobel Prize in Chemistryfor his development ofmethodology forchemical synthesison a solid matrix


Oxytocin: the first syntheticpeptide hormone

(“conquering the Himalayas”)

1902, Emil FISCHER:The first artificial peptide bond

  • What can you use synthetic peptides for?

  • Antigens to stimulate the formation of specific antibodies

  • Isolation of receptors for hormones and signalling molecules (affinity cromatography)

  • Drugs(e.g. hormone analogs)

  • Study of these can help define the rules governing the 3D structure of proteins

Peptide bonds are rigid:torsion does not occur around C(O)-NHbonds

Extent of torsion around N-C bond is denoted by dihedral angle whereas that around C-C(O) bond is denoted by dihedral angle 

Due to sterichindrance=0 AND =0cannot occur.Only certain pairsof values are permitted by thegeometries of thesuccessive peptidebonds

Ramachandran - plot for Ala

Typical occurrences of each amino acids in secondary structures

Ramachandran plot of pyruvate kinase (except Gly’s)

Human Serum Albumin would look like this, if...

X-ray diffraction

X-rays are scattered byelectrons around nucleiScattering pattern can beused for calculation of the positions of nucleiThe sample is asingle crystal

Signals of interactions over the space help us to turnthe sequence into 3D structure

Preparation of single crystals

In most cases it is by far not easy as it seems...

Nuclear Magnetic Resonance (NMR)

1H NMR spectrum of lysozyme

1 mM [13C-15N] Ubiquitin in 90% H2O-10% D2O13C-1H HSQC - An example for interaction through a chemical bond

1 mM [13C-15N] Ubiquitin in 90% H2O-10% D2OHNCA - An example for interaction through multiple bonds

Nuclear Overhauser Effect (NOE) - Interaction through the space

Diffraction: interaction with electron density

Sample: single crystal

Result: a “sharp” static snapshot with good spatial resolution

Perutz and Kendrew (1962)

Resonance: interaction with magnetic moments

Sample: isotope labelled protein

Result: a “blurry”dynamic picture of a conformational ensemble”

Wüthrich (2002) (1/2)

X-ray vs NMR

  • Stability:

  • “enthalpy side”: formation of bonds“entropy side”: rearrangement of solvent “structure”

  • Chemical bonds participating in stabilizing protein structureand agents used to cleave them:

  • disulfide bridgesmercaptoethanol, DTT

  • H-bondspH extremes

  • hydrophobic interactionsdetergents, urea

  • ionic interactionschanging pH or ionic strength

Peptides  Proteins

Motif:A distinct folding pattern forelements of secondary structure;

also called a fold orsupersecondary structure.


A distinct structural unit of a polypeptide;they may have sparate functions andthey may fold as independent, compact units


Separate polypeptide chains of the same protein

The same short sequence may take different secondary structuresdepending on its broader environment

Prion:(proteinaceous infectious only)upon dimerization it suffersdramatic conformational changeleading to spongiformdegeneration (CJD)

Reasons and mechanismare not understood


  • Functions:

  • catalysisenzymes

  • transport and storagemyoglobin, hemoglobin

  • motionactin myosin

  • defenseskin and hair proteins

  • regulationhormones, exp. factors

  • fuele.g. in plant seeds


  • Functions:


  • transport and storagemyoglobin, hemoglobin

  • motionactin myosin

  • defenseskin and hair proteins

  • regulationhormones, exp. factors

  • fuele.g. in plant seeds

Enzyme Classification

1Oxidoreductases(electron, hydride ion, H atom)

2Transferases(group transfer, e. g. phosphate, -COO, methyl)

3Hydrolases(functional groups  water)

4Lyases(formation or saturation of double bonds)


6Ligases(C-C, C-S, C-O, C-N bonds, for ATP)

Each enzyme name ends -ase, except...

Each enzyme is (basically) protein, except…

The enzyme exerts its activity in the native conformation,and the reaction takes place at the active site

Enzymes do not usually contain protein only:

apoenzyme (protein) + X = holoenzyme

X = cofactor

cofactor = inorganic ion or coenzyme (or both)

The cofactor bound to the peptide chain by covalent bond is called

prosthetic group

Some enzymes with inorganic ions as cofactors

Iron(II)-iron(III)cytochrome oxidase, catalase, peroxidase

Iron-sulfur proteinssuccinate dehydrogenase, aconitase, dinitrogenase

Copper(II)cytochrome oxidase, superoxide dismutase

Zinc(II)alcohol dehydrogenase, superoxide dismutase

Magnesiumhexokinase, glc-6-phosphatase, pyruvate kinase

Potassiumpyruvate kinase


Seleniumglutathione peroxidase

Electron, atom or group transfer coenzymes

NAD+hydride ionnicotinic acid (niacin)

FAD+electronriboflavin (B2)

CoAac(et)yl grouppantothenic acid

TPPaldehyde groupthiamine (B1)

pyridoxal phosphateamino grouppyridoxine (B6)

coenzyme B12H atoms, alkyl groups(B12)


tetrahydrofolateone-carbon groupsfolic acid


  • Functions:

  • catalysisenzymes


  • motionactin myosin

  • defenseskin and hair proteins

  • regulationhormones, exp. factors

  • fuele.g. in plant seeds

See also the Molecular Tutorial


  • Functions:

  • catalysisenzymes

  • transport and storagemyoglobin, hemoglobin


  • defenseskin and hair proteins

  • regulationhormones, exp. factors

  • fuele.g. in plant seeds


  • Functions:

  • catalysisenzymes

  • transport and storagemyoglobin, hemoglobin

  • motionactin myosin


  • regulationhormones, exp. factors

  • fuele.g. in plant seeds

What do hairdressers do when they make a permanent wave?


Collagen helices are cross-linked, mostly by hydroxyproline residues,to the formation of which ascorbic acid (vitamin C) is indispensable  that is why the lack of vitamin C caused scurvy

Silk fibroin

Spider’s net


  • Functions:

  • catalysisenzymes

  • transport and storagemyoglobin, hemoglobin

  • motionactin myosin

  • defenseskin and hair proteins

  • regulationhormones, exp. factors

  • fuele.g. in plant seeds

Online resources: (Ch3, Ch4, Ch5)

see esp. Molecular Tutorial “Protein Architecture” (Ch3, Ch4)

For online quizzing give:

as instructor’s e-mail address

  • Login