Mo. Rev. Stat. § 351.270: Bylaws may require concurrence of greater portion of shares than statutes require.

Whenever with respect to any action to be taken by the shareholders of a corporation the articles of incorporation or provisions of the bylaws adopted by the shareholders require the vote or concurrence of the holders of a greater portion of the shares, or of any class or series thereof, than required by this chapter with respect to such action, the provisions of the articles of incorporation or such provisions of the bylaws adopted by the shareholders shall control.