No abstract

Chemically modified amino acids in the silk and wool fibers treated with epichlorohydrin (E), glycidol (G) and glycidyl methacrylate (GMA), were identified by gas chromatography-mass spectrometry as their N(O )-trifluoroacetyl n-butyl ester derivatives. 0-(Dihydroxypropyl)-and O-(chlorohydroxypropyl)tyrosines, and N`-(dihydroxypropyl)-and N`,N`-bis(dihydroxypropyl)lysines were identified in all silk and wool samples, indicating that OH and Cl groups of the epoxide-amino acid adducts were labile during acid hydrolysis of the samples. N',N'-B is (chlorohydroxy pro pyl) lysine and O-[(dihydroxypropoxy)hydroxypropyl] tyrosine were also identified in the silk and wool fibers treated with G, the latter being formed by addition of a second molecule of G to O-(dihydroxypropyl) tyrosine residue. S (Dihydroxypropyl)-and S-(2-carboxypropyl) cysteines were identified by the single ion monitoring (SIM) method for the wool fibers treated with GMA, indicating that thiol groups of cysteine residues could react with both epoxy and methacryl groups of GMA. S-(Chlorohydroxypropyl) cysteine as well as S (dihydroxypropyl) cysteine were found in the other wool samples by the SIM method. N`-(Chlorohydroxypropyl)-and N`,N`-b is (chlorohy droxypro pyl) ly sines were also found in the wool fibers treated with E by the SIM method.

Amino acid analysis of the chemically modified silk fibroin samples which were obtained by the treatment with glycidol (G), epichlorohydrin (E), glycidyl methacrylate (GMA), methyl glycidyl ether (MGE), ethyl glycidyl ether (EGE), isopropyl glycidyl ether (IPRGE) and allyl glycidyl ether (AGE) in the presence of aqueous neutral salt was made by the gas-liquid chromatographic (GC) method with amino acids being converted to n-butyl esters of N, (0)-trifluoroacetyl derivatives and by the conventional ion-exchange chromato graphic method with an automated amino acid analyzer. It was found that all the chemically modified silk fibroins yielded G-tyrosine adduct, Le., O-(2,3-dihydroxypropyl)tyrosine (G-TYR) by acid hydrolysis, indicating that chlorine in E-tyrosine adduct and aliphatic ether linkages in alkyl glycidyl ether-tyrosine adducts were unstable under the hydrolytic conditions. The GC amino acid analysis revealed that, in addition to G-TYR, the G-treated silk yielded two minor products of unknown structure and the E-treated and the EGE-treated silk samples yielded E-tyrosine adduct and EGE-tyrosine adduct, respectively, when being hydrolyzed. The Kovats retention indices of the epoxidemodified tyrosines were determined on OVA 7 and on Dexsil 300 GC and the relationship between the indices and the structure of the tyrosine derivatives was discussed.

No abstract