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			The Proteax 
			module of iScienceSearch provides an easy way to perform 
			substructure and structure similarity searches in major Internet 
			databases containing peptides, such as PubChem, CheBI and ChemSpider 
			starting from plain 3-letter-code peptide sequences. 
			When 
			performing real structure searches, you can find peptides containing 
			structure modified amino acid residues. These cannot be found using 
			strictly text based searches such as BLAST. 
			
			You can also 
			search generic text terms in PubChem and CheBI and end up on a 
			result page that only contain structures that are peptides or 
			peptide like structures such as Penicillin. 
			
			In order to analyze the 
			results easily, we transform the complex structures back into 
			the 3-letter-codes. We show structures when we cannot map back to 
			the natural amino acids, see the picture below. 
			
			
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