Two novel bovine somatotropin species generated from a common dehydroalanine intermediate.
Under stressed conditions such as prolonged exposure to high pH, the C-terminal disulfide bridge in bovine somatotropin (bST) is susceptible to a base catalyzed beta-elimination reaction. This reaction converts the disulfide bond to a dehydroalanine residue with loss of a sulphur atom. Two altered species were isolated in pure form and determined to be generated from this dehydroalanine intermediate. One is a monomeric lanthionyl bST (L-bST) with a thioether linkage, and the other is an inter-molecular disulfide linked dimer containing a lysinoalanine. These two novel structures were unambiguously determined using various techniques including enzymatic digestion, amino acid sequencing and analysis, and mass spectrometry. The monomeric L-bST was demonstrated to be equipotent to normal bST in a hypox rat assay, thus showing that formation of lanthionine in place of this disulfide bond does not affect it bioactivity.
Tou
Jacob S
JS
Global Chemistry R&D, Monsanto, 800 N. Lindbergh Blvd, St. Louis, MO 63167, USA. jacob.s.tou@monsanto.com
Violand
Bernard N
BN
Chen
Zi Yi
ZY
Carroll
James A
JA
Schlittler
Michael R
MR
Egodage
Kamal
K
Poruthoor
Simon
S
Lipartito
Carol
C
Basler
Darrell A
DA
Cagney
Judy W
JW
Storrs
S Bradley
SB
D000409:Alanine / Q000031:analogs & derivatives* / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002852:Chromatography, Ion Exchange; D013006:Growth Hormone / Q000737:chemistry* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D008241:Lysinoalanine / Q000737:chemistry; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D011487:Protein Conformation; D055503:Protein Multimerization; D020539:Sequence Analysis, Protein; D013440:Sulfides / Q000737:chemistry; D053719:Tandem Mass Spectrometry
D013440:Sulfides; D008241:Lysinoalanine; C073294:growth hormone, bovine; D013006:Growth Hormone; C015102:dehydroalanine; C001520:lanthionine; D000409:Alanine