ISTANBUL, May 8 (Reuters) - Turkish participation bank Albaraka ALBRK.IS , owned by Bahrain-based Islamic lender Al Baraka, mandated banks for a sukuk issue worth maximum $500 million, it said on Thursday.Albaraka mandated BNP Paribas, Emirates NBD Capital Limited, Standard Chartered Bank and QInvest LLC as joint lead managers for the issue.(Reporting by Ece Toksabay; Editing by Dasha Afanasieva)(