The Bianconeri, looking to build on their unbeaten title triumph last season, had been in negotiations for the Zebrette pair for several weeks after they underwent medicals ahead of expected tranfers.
Ghana playmaker Asamoah, 23, has signed a five-year contract with Juve, who have purchased 50 per cent of his rights for a fee of 9million euros.
Chile anchorman Isla, 24, joins in a similar deal costing Juve 9.4m euros, with both fees payable over three years.
Co-ownership deals, which are common in Italy, allow the selling club to retain a proportion of future transfer fees unless the buying club buys out the remaining portion of the player’s rights.
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