Primary structure of thymosin beta 12, a new member of the beta-thymosin family isolated from perch liver.
A new polypeptide termed thymosin beta 12 has been isolated from perch liver and its primary structure elucidated. This polypeptide contains 43 amino acid residues with a molecular weight of 4822 Da. The content of thymosin beta 12 from perch liver has been determined as 43 micrograms/g of tissue. The amino-terminal end of this polypeptide is blocked by an acetyl group as deciphered by fast-atom bombardment mass spectrometric analysis. Sequence analysis reveals that thymosin beta 12 is 79% homologous to thymosin beta 4, an immunomodulator which was originally isolated from calf thymus. Thymosin beta 12 also shows 84% sequence homology to thymosin beta 11, a beta 4 analog which replaces beta 4 in two species of bony fish, oscar and rainbow trout. The evolutionary implication of such results will be discussed. The isolation of a new beta 4-related peptide from perch liver which differs from beta 11 indicates that beta-thymosin peptides are widely distributed in lower vertebrate classes.
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Graduate Institute of Biochemistry, National Cheng Kung University Medical College, Tainan, Taiwan, Republic of China.
Liu
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Jou
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D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D008099:Liver / Q000737:chemistry*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D010471:Perches; D016415:Sequence Alignment; D013045:Species Specificity; D013947:Thymosin / Q000737:chemistry* / Q000145:classification
D000596:Amino Acids; D010446:Peptide Fragments; D013947:Thymosin