[Borek]

Trivial, but I want to check something

Which of these two tripeptides will be not found between products of a natural polipeptyde hydrolysis:

A:


B:

[digchick21]

A

[Borek]

Any explanation?

[DrCMS]

I'd say B beacuse A is a tripiptide of three standard amino acids Asn-Cys-Gly while B is synthetic AA-Cys-Gly.

[Schrödinger]

A has Cys and Gly but I dont think it has the Asn moiety. A is Glu-Cys-Gly, isn't it?

[digchick21]

"A" isn't a natural polypeptide, in that it doesn't follow the usual joining of the peptide bond:

NH-C(R)-CO-NH-C(R)-CO-NH-C(R)-COOH

Instead the first amino acid in "A" Glutamate is joined to the next amino acid, Cysteine through its R group unlike that in "B" which follows the normal pattern.

[AWK]

GSH is quite natural but is not synthesized using peptide pathways

[Borek]

"A" isn't a natural polypeptide, in that it doesn't follow the usual joining of the peptide bond:

NH-C(R)-CO-NH-C(R)-CO-NH-C(R)-COOH

Instead the first amino acid in "A" Glutamate is joined to the next amino acid, Cysteine through its R group unlike that in "B" which follows the normal pattern.

That's the answer I was looking for.