Attachment IV - Page 30 
-8- DRAFT 
NOVEMBER 7, 1983 
For small proteins or peptides with molecular weight less than 
10,000 daltons, the demonstration of nearly Integral ratios of amino acids would 
support arguments of peptide purity. 
For proteins with molecular weight in excess of 10,000 daltons, 
the amino acid compositional analysis may not provide as useful information in 
support of the purity of the product as for the small proteins or peptides. 
However, integral values for those amino acid residues generally found in low 
quantities, such as tryptophan and/or methionine, could be obtained and used to 
support arguments of purity. 
2. Partial Sequence Analysis 
Partial amino terminal (15 residues) and carboxy terminal sequence 
analyses can serve as important criteria for the identity of recombinant DNA 
produced proteins or peptides. The sequence data presented in tabular form 
should Include the total yield for every amino acid at each cycle as well as the 
repetitive yield for the major sequence(s). Unexpected heterogeneity in the 
amino termini and carboxy termini of proteins produced by recombinant DNA 
technology due to proteolytic degradation has been revealed already by sequence 
analysis . 
3 . Peptide Mapping 
Peptide mapping can provide a very discriminating comparison between 
a recombinant DNA product and an authentic sample of the natural product or 
a reference preparation. This is best accomplished using a pure and specific 
peptidase to cleave the proteins under identical conditions, followed by either 
two-dimensional electrophoresis or high performance liquid chromatography. In 
conjunction with amino acid composition and sequence analysis of each peptide, 
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