Proteiner og proteinsstrukturer

Question 1

Hva er alle proteiner bygd opp av?

Answer 1

The amine and carboxylic acid functional groups found in amino acids allow them to have amphiprotic properties; a molecule (or compound) that can both donate and accept a proton.

Carboxylic acid groups (-CO2H) can be deprotonated to become negative carboxylates (-CO2- ), and α-amino groups (NH2-) can be protonated to become positive α-ammonium groups (+NH3-).

At pH values greater than the pKa of the carboxylic acid group (mean for the 20 common amino acids is about 2.2), the negative carboxylate ion predominates.

At pH values lower than the pKa of the α-ammonium group (mean for the 20 common α-amino acids is about 9.4), the nitrogen is predominantly protonated as a positively charged α-ammonium group.

Thus, at pH between 2.2 and 9.4, the predominant form adopted by α-amino acids contains a negative carboxylate and a positive α-ammonium group, so it has net zero charge.

This molecular state is known as a zwitterion, from the German Zwitter meaning hermaphrodite or hybrid.

Below pH 2.2, the predominant form will have a neutral carboxylic acid group and a positive α-ammonium ion (net charge +1), and above pH 9.4, a negative carboxylate and neutral α-amino group (net charge -1).

Amino acids also exist as zwitterions in the solid phase, and crystallize with salt-like properties unlike typical organic acids or amines.

Question 2

Hva deler man aminosyrer inn i?

Answer 2

Question 3

Hvordan foregår ioniseringen av aminosyrer og peptider?

Answer 3

Question 4

Hvordan kan man dele inn aminosyrene i ulike klasser?

Answer 4

Question 5

Hvilken type binding dannes mellom aminosyrer?

Hvor skjer dette?

Answer 5

Question 6

Hva er det som gir opphav til proteinenes tredimensjonale struktur?

Answer 6

Question 7

Hvilke protein viste man først strukturen til?

Hva kom som en overraskelse?

Answer 7

Question 8

Hvilke kjemiske bindinger finner man i proteiner?

Answer 8

Question 9

Hva legger man i proteiners primærstruktur?

Answer 9

Question 10

Hvilke post-translasjonelle modifikasjoner forekommer ofte med proteiner?

Answer 10

Question 11

Hva mener man med proteiners sekundærstruktur?

Answer 11

Question 12

Hva er 𝛼-helikser?

Answer 12

Question 13

Hva er 𝛽-sheets?

Answer 13

Question 14

Hva er “loop”/”turn”-regioner?

Answer 14

Question 15

Hva legger man i proteiners tertiærstruktur?

Answer 15

Question 16

Hva mener man med proteiners kvartærstruktur?

Answer 16

Question 17

Hva mener man med motin/domene når det kommer til proteiner?

Answer 17

Question 18

Nevn eks. på ulike proteiner fra:

Hår/hud

Blod

SNS

Enzymer

Cellulære “anleggsarbeidere”

Antistoffer

Muskler

Answer 18

Question 19

Kan man “forutsi” proteiners struktur ut fra aminosyresekvensen?

Answer 19

Strukturprediksjon er et svært aktivt forskningsfelt, og hver sommer arrangeres “olympisk mesterskap” innen feltet.

https://fold.it/about_foldit

Question 20

Hva skjer hvis proteinfoldingen er feil?

Hvilke sykdommer er koblet opp til dette?

Answer 20

https://www.youtube.com/watch?v=cAJQbSLlonI

https://www.youtube.com/watch?v=qBRFIMcxZNM

https://www.youtube.com/watch?v=vyvwMBomSqo