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papain vs. pepsin

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briteyellowness:
(it might not be a chem question, but i'm just giving it a shot)

i'm trying to see mixing with what will clumb with type A blood cells.

the answer was antibodies isolated from the serum of a type B patient and treated with papain.

i understand why it's anti B antibodies, but i picked treated with pepsin.  what's the difference between pepsin and papain.  i know they cut below and above the disulfide bond respectively, but that doestn' help me solve the question does it?

thanks!

savoy7:
just some thoughts - not an answer

pepsin cleaves aromatic amino acids and tends to work at an acidic pH

papain works on the sulfide bonds, cysteine can activate it, tends to work at neutral pH and will spilt IgG by the hinge region.  The antibody forms 2 Fab fragments and 1 Fc fragment.  These fragments are then purified with an ion-exchange column or protein A.

From what i have read - pepsin tends to produce Fab' fragments while papain in the presence of cysteine produces Fab fragments


probably not much help to you
s

paperclip:
I've been looking up the chemical activity of amide. Seems that amides aren't so reactive. But enzymes have a way of cleaving the amide into two.

Kelvar is a polyamide and so is nylon, the former having 'aromatic groups' while the latter is just 'straight chain alkane group attached'

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