Estrutura de ProteínasEstrutura de Proteínas

Figure 2.5. O pI é o pH onde a carga líquida da proteína é ZERO. A pH’s menores a proteína tem carater CATIÔNICO e a pH’s acima do pI aniônico.

Lembra que pKa é “invariável” o termo variável é o pH.

Força Iônica e Enovelamento de Proteínas.

AA´s básico e ácidos

-S-S-, H///O, cargas, VDW, uréia

A partir da seq. 1ária, possibilidades de enovelamento enorme!!Como sabe?? Proteínas que ajudam no Enovelamento “Folding”

Efeito de íons,

Espcificidade de íons, Caotrópicos e CosmotrópicosDenaturam “Naturam”

1 = 1,5 Å Anstieg pro Aminosäurerest2 = 5,4 Å = 3,6 Aminosäurereste pro Windung3 = 27 Å entspricht 18 Aminosäurereste

auf 5 Windungen4 = 26°

auf 5 Windungen4 = 26°5 = 5,1 Åw1 - w5 = je 1 Helix-windung

3,6 resíduos de aminoácido por “passo” ~ 5.4 ªEstabilizado por H-ponte entre. Como devem ser os grupos R? e o interior da Hélice??

.

Folha anti paralela

endothelin angiogenin lysozyme mellitin

collagen thioredoxin hemoglobin

Brookhaven Protein Data Bank

The Brookhaven Data Bank will contain the most recent entries of all protein structural data. Proteins can easily be searched by using Brookhaven's PDB Gopher. When the box appears type in any key word. If a match appears, select the protein of your choice. Three files will appear: *.biblio, *.full, and *.gif. The first file will only give the information found in the header, it will not give coordinate data, the *.full file gives all data and is needed if you wish to manipulate structures from your own terminal. The *.gif file will contain a single image of the molecule. Remember that many cases several structures will be found for the same keyword. As an example try typing in pepsin after clicking here Next click on one of the many structures that show up on screen. Take a look at each of the files (*.biblio, *.full, *.gif) that are available from screen. Take a look at each of the files (*.biblio, *.full, *.gif) that are available from Brookhaven.

For more information about the Brookhaven Protein Data Base connect to their home directory which contains FTP access to recent PDB Newsletter. A searchable index by key words can be used to search the Newsletter.

Proteínas de membrana:

-Integrais-Periféricas

Figure 4.19

Name Type Specificity

Cyanogen Bromide

Chemical Carboxyl Side of Methionine

Trypsin Enzymatic Carboxyl Side of Basic Amino Acidse.g. Lys & Arg

Chymotrypsin Enzymatic Carboxyl Side of Aryl Amino Acidse.g. Phe, Tyr & Trp

Síntese de Peptídeos

The Merrifield Peptide Synthesis

The Merrifield Peptide Synthesis