Mo. Rev. Stat. § 174.220: No officer or employee shall be interested in the sale of school supplies or property.

No president, professor, teacher, regent or other officer or employee shall keep for sale or be interested, directly or indirectly, in the sales of any school furniture or apparatus, books, maps, charts or stationery used in said colleges; nor be interested, directly or indirectly in any contract or purchase for building or repairing any structure, or for fencing or ornamenting the grounds, or furnishing any supplies or material for the use of such state teachers colleges.