Mo. Rev. Stat. § 443.030

That in the absence of fraud, every acknowledgment of a deed of trust conveying any real estate in this state, taken before the trustee in said deed named, at least one year prior to the date this section shall take effect, shall be deemed valid and binding, and the fact that such acknowledgment was taken before said trustee shall not in any manner affect the title to the real estate therein described, in the hands of a purchaser who in good faith has purchased, or shall hereafter purchase, such real estate at a trustee's sale held in accordance with and under the terms of said deed of trust.