Evolution of Pancreatic Ribonucleases
Pancreatic ribonucleases form a group of homologous proteins found in considerable quantities in the pancreas of a number of mammalian taxa and of a few reptiles (Barnard, 1969; Beintema et al., 1973). The ribonuclease activity found in different species varies greatly. Large quantities are found in species which are ruminants or have a ruminant-like digestion, but also in a number of species with coecal digestion. Barnard (1969) proposed that elevated levels of pancreatic ribonuclease are the response to the need to digest the large amounts of ribonucleic acid derived from the microflora of the stomach of ruminants. As rumination and ruminant-like digestion have evolved several times independently during the evolution of mammals (Moir, 1968), pancreatic ribonucleases may well show different solutions to the same evolutionary pressure.
KeywordsRibonucleic Acid Parsimonious Tree Ribonuclease Activity Fallow Deer Pancreatic Ribonuclease
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