The role of trypsin in the pre-treatment of chromosomes for Giemsa banding.

The role of trypsin in the elicitation of G-banding on human chromosomes was studied in two separate laboratories. Enzyme activity and ability of trypsin to chelate calcium were manipulated by dilution of the treatment solution, and by inhibition with diisopropylphosphofluoridate, diphenylcarbamyl chloride, or soybean trypsin inhibitor. In all cases, chromosomes were affected in proportion to the enzyme activity of the treatment solution rather than the ability of the solution to bind calcium. It is concluded that calcium chelation is not sufficient to explain G-banding trypsin, but that proteolytic activity is required.