Studies on Cotyledonsin vitro: Factors Regulating Urease

Factors controlling urease levels in sterile cultures of jackbean cotyledons were investigated. Urea, thiurea, not increased rates of growth favour higher urease activity. Higher urease levels in the urea-treated set were attributed to substrate protection and/or induction of urease Lower urease activity in the absence of thiourea may be due to inhibition of urease by metabolically produced ammonia and increased protose activity. Utilization of ammonia in protein synthesis, lower protease activity, and possible induction of urease by thiourea in fast-growing tissues of cotyledons may lead to higher urease activity. High temperature low pH, and the presence of EDTA, hydroxyurea, or actinomyhcin D cause a faster decrease in urease units.