GlaxoSmithKline has completed its acquisition of Sirtris Pharmaceuticals, Inc. for approximately $720 million in cash. Through the acquisition GSK has enhanced its metabolic, neurology, immunology and inflammation research efforts by establishing a presence in the field of sirtuins, a recently discovered class of enzymes believed to be involved in the ageing process.     Sirtris will become part of GSK’s Drug Discovery organization, while continuing to operate from labs in Cambridge, MA...