Non-enzymatic covalent binding of radioactivity from [14C]thiourea to rat lung protein. 
In vitro covalent binding of radioactivity from [14C]thiourea (TU) to rat lung protein occurs in the presence of 100% CO2.  Prior boiling of lung slices results in a subsequent increase in covalent binding.  Covalently bound radioactivity was released from rat lung homogenates and acid-insoluble protein obtained from animals treated with [14C]TU.  The release was achieved with ammonium ion.  One possibility suggested by these results is that the bound species may involve binding of isothiocyanic acid via a thiocarbamylation reaction.