Evolution of Phosphorylase Activity in an Ancestral Glycosyltransferase.

The reconstruction of ancestral sequences can offer a glimpse into the fascinating process of molecular evolution by exposing the adaptive pathways that shape the proteins found in nature today. Here, we track the evolution of the carbohydrate-active enzymes responsible for the synthesis and turnover of mannogen, a critical carbohydrate reserve in parasites. Biochemical characterization of resurrected enzymes demonstrated that mannoside phosphorylase activity emerged in an ancestral bacterial mannosyltransferase, and later disappeared in the process of horizontal gene transfer and gene duplication in .

Building mutational bridges between carbohydrate-active enzymes.

The commercial value of specialty carbohydrates and glycosylated compounds has sparked considerable interest in the synthetic potential of carbohydrate-active enzymes (CAZymes). Protein engineering methods have proven to be highly successful in expanding the range of glycosylation reactions that these enzymes can perform efficiently and cost-effectively. The past few years have witnessed meaningful progress in this area, largely due to a sharper focus on the understanding of structure-function relationships and mechanistic intricacies.

Two brothers with mental retardation discordant for the fragile-X syndrome.

We describe two male sibs with mental retardation discordant for the fragile-X syndrome. In the younger sib, chromosome analysis under folate deprivation showed a fragile site at Xq27.3 in 12-46% of mitoses.