Identification of structural proteins of phages JWAlpha and JWDelta by SDS-PAGE analysis. Protein profiles of JWDelta and JWAlpha. Proteins were separated on a 17.5% SDS-PAGE. After extraction of gel slices from corresponding bands and tryptic digestion, samples were analyzed via peptide mass fingerprinting. Proteins identified by peptide mass fingerprinting analysis are listed aside along with their approximate molecular weight.