The trustees shall have the care, custody and control of the real and personal property of the corporation, subject to the direction of the congregation, church or society, and may, when directed by the congregation, church or society, erect houses or buildings and improvements, and repair and alter the same, and may, when so directed, mortgage, incumber, sell and convey any real or personal estate of such corporation, and enter into all lawful contracts in the name of and in behalf of such corporation: but no mortgage, incumbrance, sale or conveyance shall be made of any such estate, so as to defeat or destroy the effect of any gift, grant or legacy which may be made to such corporation; but all such gifts, grants and legacies shall be appropriated and used as directed or intended by the person or persons making the same. However, this limitation on the disposition of real or personal property does not apply to the extent that a restriction imposed by a donor on the use of an institutional fund may be released by the governing board of an institution under the Uniform Prudent Management of Institutional Funds Act.