Mo. Rev. Stat. § 356.051

Professional corporations may be incorporated for the purpose of rendering one or more types of professional service, and services ancillary thereto, and in addition, for any purpose or purposes for which corporations may be organized under the general and business corporation law of Missouri, chapter 351, to the extent that such combination of professional services or of professional services and business purposes is expressly permitted by the licensing authorities that regulate each of such professions. Except to the extent that such a combination is permitted by such licensing authorities, a professional corporation may be organized under sections 356.011 to 356.261 only for the purpose of rendering a single type of professional service and services ancillary thereto.