PEPTIDE-MAPPING OF RECOMBINANT HUMAN PARATHYROID-HORMONE BY ENZYMATICDIGESTION AND SUBSEQUENT FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRY

Peptide maps of recombinant human parathyroid hormone (rhPTH) were det ermined by both trypsin and V-8 protease digestion with subsequent fas t-atom bombardment mass spectrometry (FAB-MS). Coverage of the sequenc e was 85% when using trypsin and 90% when using V-8 protease. Five rhP TH variants that were recombinantly produced as models of Asn deamidat ed type degradation products were measured, and molecular weight diffe rences between their respective deamidated peptide fragments were comp letely detected, In the V-8 protease digests of some variants, charact eristic peptide ions caused by the deamidation were observed and this greatly facilitated the assignment and recognition of the deamidated p osition. Our data suggest that FAB-mapping of rhPTH via the protease d igestion methods used, appears to have great potential for structural investigations of the peptide.