Ribonuclease A (RNase A) belongs to an endoribonuclease class of ribonucleases. In contrast to exoribonucleases which cleave/degrade RNA in 3’-5’ direction, endoribonucleases degrade RNA endoribonucleolytically in 5’-3’ direction.
RNase A is a digestive enzyme which is secreted by the pancreas to digest RNA. It is abundantly present in the pancreas, therefore, the pancreas is a valuable source for RNase A.
Mature bovine pancreatic RNase A only has 124 amino acids with molecular weight 13.7 kDa. It lacks tryptophan amino acid.
In contrast to others known members of endoribonuclease, RNase A is not a glycoprotein.
RNase A is active under a wide range of reaction conditions (temperature range 15 – 70 °C; pH range 6–10). The optimal temperature for its activity is 60 °C and optimal pH is 7.6.
RNase A is quite stable to both heat and detergents.
It cleaves both single-stranded and double-stranded RNA as well the RNA strand in RNA-DNA hybrids at a low salt concentration (0 to 100 mM NaCl). However, it specifically cleaves single-stranded RNA at higher salt concentration (0.3M NaCl or higher)