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Protein allostery is a vitally important protein function that has proven to be a vexing problem to understand at the molecular level. Allosteric communication is a hallmark of many protein functions. However, despite more than four decades of study the details regarding allosteric communication in protein systems are still being developed. Engineering of LacI and related homologues to confer alternate allosteric communication has shed light on the pre-requisites for the de novo design of allosteric communication. While the de novo design of an allosteric pathway and complementary functional surfaces has not been realized, this review highlights recent advances that set the stage for true predictive design for a given protein topology. [ABSTRACT FROM AUTHOR]

The stereoselective peracetylation of α- d -xylose ( 1 ) and α- l -arabinose ( 4 ) using a combination of triethylamine and acetic anhydride in the presence or absence of a catalytic amount of dimethylaminopyridine (DMAP) is described. The peracetylated d -xylose and l -arabinose alpha pyranose anomers 2α and 5α are obtained in 97% and 56% yields respectively. The peracetylated d -xylose beta pyranose anomer 2β is obtained in 71% yield through simple modification of the reaction conditions. Details regarding synthesis and isolation optimization studies under different conditions are presented below. The stereoselective peracetylation reactions disclosed here have been used to separate mixtures of d -xylose and l -arabinose as their peracetylated derivatives 2β and 5α in 47% and 42% yields and can provide pure pentoses after deacetylation. [ABSTRACT FROM AUTHOR]