Question: When did Grgur Branković's mother die?
Sentence (from "Irene Kantakouzene"): Irene Kantakouzene ("Eiréne KantakouzenéEiríni KantakouziníIrina Kantakuzin"; 1400 – May 3, 1457), known simply as Despotess Jerina (/ "despotica Jerina"), was the wife of Serbian Despot Đurađ Branković.
Relevant evidence: Yes