Fluorogenic substrates for hydrolase detection following electrophoresis

[Chemoenzymatic synthesis of new fluorogenous substrates for cysteine proteases of the papain family]

A chemoenzymatic syntheses was developed for new highly specific fluorogenic substrates for cysteine proteases of the papain family, Abz-Phe-Ala-pNA (I) and Glp-Phe-Ala-Amc (II) (Abz, pNA, Glp, and Amc are i-aminobenzoyl, p-nitroanilide, pyroglutamyl, and 4-amino-7-methylcoumaride, respectively). Substrate (I) was obtained in an aqueous-organic medium using native chymotrypsin. Substrate (II) was synthesized in DMF-MeCN by the treatment with chymotrypsin and subtilisin Carlsberg immobilized on polyvinyl alcohol cryogel. Hydrolysis of substrate (I) with papain, ficin, and bromelain was accompanied by a 15-fold increase in fluorescence intensity, and that of substrate (II), by a change in the fluorescence spectrum. Unambiguity of enzymatic hydrolysis of the substrates after the Ala residue was shown. The specific activity of the substrate hydrolysis with papain, bromelain, and ficin and was determined. Papain showed the greatest activity for both substrates. The activity of all proteases under study was essentially higher for substrate (II), than for substrate (I). The lowest detectable papain concentrations were 2.4 x 10(-10) M for (I) and 1.2 x 10(-11) M for (II). A high selectivity of cysteine proteases for Glp-Phe-Ala-Amc was established.

Glycosynthase-Catalysed syntheses at pH below neutrality

The use of the new glycosynthase Ta-beta-GlyE386G and of the already known Ss-beta-GlyE387G for the synthesis of interesting 4-methylumbelliferyl disaccharides and for the galactosylation of alpha- and beta-xylosides of 4-penten-1-ol is reported. The results show satisfactory yields of reaction in presence of low excesses of acceptors and demonstrated that the high activity of these enzymes at pH below neutrality is applicable in the transfer of glucose as well as of galactose from the preferred 2-NP-based donors.