Mammalian ribonucleases. The absence of a glycosylated Asn-Pro-Thr sequence in horse ribonuclease and the presence of tryptophan at position 39 in horse and dromedary ribonuclease.

This research analyzes parts of the amino acid sequences of horse and dromedary pancreatic ribonuclease, discovering that horse ribonuclease does not contain a glycosylated Asn-Pro-Thr sequence and that both horse and dromedary ribonucleases have tryptophan at position 39.

Amino Acid Sequences Investigation

• The study was focused on reevaluating parts of the amino acid sequences found in horse and dromedary pancreatic ribonuclease. The researchers specifically looked at the sequence of residues, which denotes the order of amino acids in a protein, ranging from 21 to 25 in horse ribonuclease.
• It was found that the sequence in question is either Ser-Asn-Pro-Thr-Tyr or Ser-Asn-Ser-Thr-Tyr. In the latter sequence, the asparagine (Asn) is glycosylated, which means a sugar molecule is attached to it. However, the absence of a glycosylated Asn-Pro-Thr sequence was noted in horse ribonuclease.

Presence of Extra Amino Acid Residues and Tryptophan

• The researchers also found that horse ribonuclease contains four additional amino acid residues at the C-terminus. The C-terminus is the end of an amino acid chain and the presence of additional residues there is also found in a number of other ribonucleases.
• Another important discovery from the study is that the horse and dromedary ribonucleases have tryptophan at position 39. Tryptophan is an essential amino acid that the body cannot produce and must be obtained from the diet. Its presence was detected at the 39th position in the ribonuclease amino acid sequence of both the horse and dromedary.