Re: Specificity of chymotrypsin
Ioannis Papayannopoulos (iap@intrex.net)
Thu, 25 Sep 1997 22:02:31 -0400
I have never observed chymotrypsin cleave at Asp or Glu or Ala, but I
have seen a few times cleavages after Asn, Lys, or Arg. However, the
latter two might have been due to contamination with trypsin; I have
injected commercial chymotrypsin on a RP-HPLC and saw a number of peak,
some of which are autolysis products but some are probably due to other
protein contaminants. Although the literature states that cleavage
after Leu occurs more slowly than after the aromatic amino acids, in my
experience Leu is as good a site for chymotryspin as Phe, Trp, and Tyr
(Met is, indeed, not as good).
Ioannis Papayannopoulos
Covance Biotechnology Services
Research Triangle Park, NC
On Thu, 25 Sep 1997, Kenneth Williams wrote:
> The product literature with our sequencing grade chymotrypsin states this
> enzyme cleaves at Tyr, Phe, Trp and (at a lower rate) at Leu, Met, Ala, Asp
> and Glu. Has anyone documented reasonable rates of cleavage at Asp/Glu?
> Is there a good reference(s) that documents relative rates of cleavage at
> different residues in intact, denatured proteins?
>
> Thanks,
> Ken Williams
>
>