question from organic odyssey?

[humcar22]

Trypsin cleaves on the carboxy side of Lys and Arg...

so I'm wondering why when the sequence Ala-Val-Lys-Pro-Pro-Ser-Arg-Arg-Val-Pro is cleaved by trypsin, the result is:

Ala-Val-Lys + Pro-Pro-Ser-Arg + Arg-Val-Pro

why is the Arg-Val bond not also cleaved? please help! D:

---

Members don't see this ad.

 

[WolfsBane]

Trypsin cleaves on the carboxy side of Lys and Arg...

so I'm wondering why when the sequence Ala-Val-Lys-Pro-Pro-Ser-Arg-Arg-Val-Pro is cleaved by trypsin, the result is:

Ala-Val-Lys + Pro-Pro-Ser-Arg + Arg-Val-Pro

why is the Arg-Val bond not also cleaved? please help! D:

I don't believe it will cut an amino acid free completely


Sent from my iPhone using SDN mobile

 

[deleted738762]

Just used Wikipedia "Trypsin cleaves peptide chains mainly at the carboxyl side of the amino acids lysine or arginine, except when either is followed by proline" In that it is followed by Pro so it won't happen. A bit weird because lys the first part is followed by Pro, yet it's cut. Also, the organic chemistry section on the DAT is super easy compared to destroyer and probably even odyssey. Good luck

Trypsin - Wikipedia

 

[DAT Destroyer]

Trypsin cleaves on the carboxy side of Lys and Arg...

so I'm wondering why when the sequence Ala-Val-Lys-Pro-Pro-Ser-Arg-Arg-Val-Pro is cleaved by trypsin, the result is:

Ala-Val-Lys + Pro-Pro-Ser-Arg + Arg-Val-Pro

why is the Arg-Val bond not also cleaved? please help! D:

The carboxy side means cut to the RIGHT of the residue...i.e the right side of Lys or Arg......Thus cutting to the right of Lys and Arg gives the sequences above. Arg Val is NOT cut.....since this dipeptide would mean that you cut on the carboxy side of Val. Remember the concept as to why we cleave certain bonds. The answer is the binding pocket !!!! Many reagents cut only aromatic residues because the binding pockets properly fit these amino acids. Sometimes they work by charge as well......Lys and Arg for example are positively charged residues, hence the binding pocket that best attracts these amino acids would be negatively charged. Those that cut smaller amino acid residues are smaller in size.

Hope this helps.

Dr. Romano

 

[humcar22]

Thank you so much for your answer! However, while everything else makes sense, I am still just a little confused on the following:

The carboxy side means cut to the RIGHT of the residue...i.e the right side of Lys or Arg......Thus cutting to the right of Lys and Arg gives the sequences above. Arg Val is NOT cut.....since this dipeptide would mean that you cut on the carboxy side of Val.

But perhaps I wasn't quite clear on what I was saying. I didn't mean cleaving Ala-Val off together, but rather cleaving between them. To the C side of alanine (N side of valine), and not the carboxy side of valine.

When working out the problems, I would have guessed AVK PPSR R VP