Sensitivity of the antibovine parathyroid hormone serum 211/32 to synthetic fragments of human parathyroid hormone.

The specificity of the guinea pig antibovine parathyroid hormone (anti-bPTH) serum, AS 211/32, for various regions of the PTH molecule was tested with synthetic fragments of human PTH (hPTH). The antiserum detected both hPTH-(1-34) and hPTH-(44--68) at about 0.5 fmol/tube but was 3- to 20-fold less sensitive to hPTH-(53--84). Nine of 10 anti-PTH sera also recognized hPTH-(44--68) better than hPTH-(53--84). The sensitivity of AS 211/32 and 6 other antisera to the amino-terminal region was highly dependent upon the nature of the tracer bPTH. One of 3 lots of highly purified bPTH tracer yielded assays which detected hPTH-(1--34) poorly. AS 211/32 is not purely an amino-terminal antiserum and with some tracer preparations may show little amino-terminal specificity.