No abstract

Carbohydrate structures are often complex. Unfortunately, synthesis of the range of sugar combinations precludes the use of a single coupling protocol or set of reagents. Adapting known, reliable bench-chemistry reactions to work via automation will help forward the goal of synthesizing a broad range of glycans. Herein, the preparation of di- and tri-saccharides of alpha 1→2 rhamnan fragments is demonstrated using thioglycoside donors with the development for a solution-phase-based automation platform of commonly used activation conditions using N-iodosuccinimide (NIS) with trimethylsilyl triflate. Byproducts of the glycosylation reaction are shown to be compatible with hydrazine-based deprotection conditions, lending broader functionality to this method as only one fluorous-solid-phase extraction step per coupling/deprotection cycle is required.

No abstract

Glycoscience continues to be an underrepresented topic in current undergraduate-biochemistry-laboratory curricula. Of the educational laboratories present in this subject area, few introduce students to cutting-edge methods and techniques related to carbohydrates. A multiweek series of experiments is described that highlights a recently published bleach-mediated-carbohydrate-cleavage protocol in the context of the isolation and identification of the soybean glycoprotein, βconglycinin. Two different levels of undergraduate biochemistry courses (a first-year introductory course and an upper-level bioanalytical course) completed the experimental set. Although the same sequence of experiments took place for both levels, the teaching approaches to the material varied. The introductory course used an inquiry-type learning approach, whereas the upper-level students were taught with a guided-inquiry approach. Students in both courses were able to successfully isolate glycosylated β-conglycinin from inexpensive soy flour and then analyze the protein with SDS-PAGE and mass spectrometry. Once β-conglycinin was isolated, students were able to effectively adapt a recently published bleach-mediated-carbohydrate-cleavage protocol on this previously untested glycoprotein and quantitate the carbohydrate content with a colorimetric phenol−sulfuric acid assay. The effective execution of this biochemistry-laboratory series demonstrates an alternative undergraduate-laboratory curriculum that introduces students to traditional glycoscience and protein methods along with more cutting-edge techniques in these areas.