2. β-Glucuronidase-coupled assays of glucuronoyl esterases
Lucia Fraňová, Vladimír Puchart, Peter Biely Anal Biochem. 2016 Oct 1;510:114-119. doi: 10.1016/j.ab.2016.07.023. Epub 2016 Jul 22.
Glucuronoyl esterases (GEs) are microbial enzymes with potential to cleave the ester bonds between lignin alcohols and xylan-bound 4-O-methyl-d-glucuronic acid in plant cell walls. This activity renders GEs attractive research targets for biotechnological applications. One of the factors impeding the progress in GE research is the lack of suitable substrates. In this work, we report a facile preparation of methyl esters of chromogenic 4-nitrophenyl and 5-bromo-4-chloro-3-indolyl β-D-glucuronides for qualitative and quantitative GE assay coupled with β-glucuronidase as the auxiliary enzyme. The indolyl derivative affording a blue indigo-type product is suitable for rapid and sensitive assay of GE in commercial preparations as well as for high throughput screening of microorganisms and genomic and metagenomic libraries.
3. Derivatives of S-9-fluorenylmethyl-L-cysteine
M Bodanszky, M A Bednarek Int J Pept Protein Res. 1982 Nov;20(5):434-7. doi: 10.1111/j.1399-3011.1982.tb03064.x.
The 9-fluorenylmethyl (Fm) group was examined with respect to its potential for blocking the sulfhydryl function. The S-Fm group is resistant to acids and to catalytic hydrogenation but is cleaved by ammonia in methanol or by organic bases, such as a 20% solution of piperidine in dimethylformamide. Synthesis of N-tert.-butyloxycarbonyl-S-9-fluorenylmethyl-L-cysteine p-nitrophenyl ester and of cysteinyl peptides protected with the S-Fm group are described.
