Oxidation of recombinant human parathyroid hormone: effect of oxidized position on the biological activity.
OBJECTIVE
To determine the oxidation products of recombinant human parathyroid hormone (rhPTH) treated with H2O2, the amino acid residue oxidized, and the biological activity of the oxidation products.


METHODS
Oxidized residues were determined by CNBr cleavage, trypsin digestion and subsequent fast atom bombardment mass spectrometry. The biological activity of each oxidized rhPTH was examined in rat osteosarcoma cell adenylate cyclase assay.


RESULTS
Three oxidized products were isolated, namely, Met at position 8 (Met8) sulfoxide, Met at position 18 (Met18) sulfoxide and both positions Met sulfoxide. It appears that the Met8 and Met18 oxidized forms are intermediates in the generation of the Met doubly oxidized form. All oxidized forms possessed reduced biological activity, more so for oxidation at Met8 than at Met18.


CONCLUSIONS
The region around Met8 is important for the activity of the parathyroid hormone.
Nabuchi
Y
Y
Preliminary Drug Evaluation Laboratory, Chugai Pharmaceutical Co., Ltd., Shizuoka, Japan.
Fujiwara
E
E
Ueno
K
K
Kuboniwa
H
H
Asoh
Y
Y
Ushio
H
H
D002851:Chromatography, High Pressure Liquid; D000242:Cyclic AMP / Q000378:metabolism; D006801:Humans; D010281:Parathyroid Hormone / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry*; D013997:Time Factors; D014357:Trypsin / Q000737:chemistry
D010281:Parathyroid Hormone; D011994:Recombinant Proteins; D000242:Cyclic AMP; D014357:Trypsin