Amino acid sequence of the fetal chain of yak haemoglobin.

The amino acid sequence of the fetal chain of yak haemoglobin was determined. The sequence is the same as that of the fetal chain of bovine haemoglobin. Phenylalanine is present at position 12 of the helix A in the fetal chain while tryptophan is the amino acid at this position in the β-chain of yak adult haemoglobin. This amino acid replacement may be responsible for the higher oxygen affinity of yak fetal haemoglobin than yak adult haemoglobin.