The state does pledge to and agree with the holders of the bonds or notes issued pursuant to authority contained in this chapter that the state will not limit or restrict the rights hereby vested in the bank to purchase, acquire, hold, sell or dispose of utility bonds or other investments or to make loans to public utilities or to establish and collect such fees or other charges as may be convenient or necessary to produce sufficient revenues to meet the expenses of operation of the bank, and to fulfill the term of any agreements made with the holders of its bonds or notes authorized by this chapter or in any way impair the rights or remedies of the holders of such bonds or notes until the bonds and notes, together with interest thereon, and interest on any unpaid installments of interest, and all costs and expenses in connection with any action or proceedings by or on behalf of such holders are fully met, paid and discharged.