Mo. Rev. Stat. § 348.160

The state does hereby pledge to and agree with the holders of any notes or bonds issued under sections 348.005 to 348.180 that the state shall not limit or alter the rights hereby vested in the authority to fulfill the terms of any agreement made with such holders thereof, nor in any way impair the rights and remedies of such holders until such notes and bonds, together with the interest thereon and the interest on any unpaid installments of interest, and all costs and expenses in connection with any action or proceeding by or on behalf of such holders, are fully met and discharged. The authority is authorized to include this pledge and agreement of the state in any agreement with the holders of such notes or bonds.