... fromanion-exchange (AE) HPLC of water-soluble matrix (WSM) and EDTA-soluble matrix (EDTA-SM). Cysteine, hydroxylysine, hydroxy-proline, phosphoserine, proline and tryptophan were not determined.Amino acid AE-WSM ... Hydroxyproline, hydroxy-lysine and phosphoserine were not detected in WSM, WIM,EDTA-SM and EDTA-IM.The comparison of the amino acid composition of themain peak obtained from AE-HPLC of WSM and ... hydroxyproline and hydroxylysine were examined at 254 nm by reverse-phaseHPLC of their phenylisothiocarbamate derivatives [26], asreported previously [20]. The serine, threonine and tyrosinecontents...