Giuseppina Operti was born in Turin (Italy) on November 16, 1871 into a wealthy family.

She was tested by the death of her brother and father within three months. Together with her mother, she gave herself to a more intense Christian life, also joining the Carmelite Third Order. When she learned from the parish priest of Marene, a town where her family had some possessions, that the rumour was circulating that she would found an institute for poor girls, she took it as a sign of God's will for her: in 1894, in the palace inherited from relatives she inaugurated the Saint Joseph Institute.

Urged by the Archbishop of Turin, Monsignor Davide Riccardi, she began a religious community of Carmelite Tertiaries, who lived the active apostolate of the spirituality of the great reformers of Carmel:

On March 19, 1895, with her religious profession, she changed her name to Sister Mary of the Angels, in honour of the Carmelite Blessed of the same name. Her yearning for cloistered life seemed satisfied when she then entered Carmelite monastery of Moncalieri, but she had to leave for health reasons.

She led the Institute of Tertiaries (which since March 14, 1970 bears the name of Carmelite Sisters of St. Teresa of Turin) in the formation of two branches: a contemplative one, later housed in the new monastery of Cascine Vica, and one of active life, but centred on contemplation.

She spent her last years in the monastery of Cascine Vica, where she died on October 7, 1949.

The decree on her heroic virtue was promulgated on June 16, 2017.