Pharmaceuticals giant GlaxoSmithKline is to buy up over a quarter of UK-based biotech firm Autifony Therapeutics through its wholly-owned subsidiary, Glaxo Group.Glaxo is to invest £1.25m in Autifony is exchange for a 25.4% minority equity stake.Autifony will issue 850,000 A ordinary shares to Glaxo "in exchange for a number of pre-candidate voltage-gated ion channel modulator compounds and associated patent applications and data for development in hearing loss," the statement said.Some 571,429 Series A preferred shares will also be issued for £400,000 of development work funded by the FTSE 100 firm.Furthermore, on the achievement of a "pre-determined milestone" - at which there will be a further investment by investors - Glaxo will be eligible to receive a further 500,000 A ordinary shares. On a fully diluted basis, Glaxo will then own 13.2% of Autifony.BC