Procedure 3 Papain, leucine aminopeptidase, prolidase

Procedure 3 papain, leucine aminopeptidase, prolidase This early procedure for enzymic hydrolysis of proteins was reported by Hill and Schmidt (1962) to be successful for hydrolysis of several proteins. Papain was found to be superior to subtilisin or a combination of trypsin and chymotrypsin for the initial hydrolysis. The method might be improved if aminopeptidase M (discovered after the method was developed) is used in place of the leucine aminopeptidase, but to our knowledge this has not been tested. The problem with diketo-piperazine formation from X-Pro dipeptides in aminopeptidase M hydrolysates of peptides (see above) may make this substitution less desirable than it would seem at first. 

The dried peptide mixture is redissolved in 1-2 ml H2O and adjusted to pH S.4-8.6 with dilute NaOH. Tris buffer (other buffers can be substituted to prevent interference with any subsequent analyses) (0.5 M at pH 8.5) and MnCl2 (0.025 M) are added to give final con- 

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