Human prostatic acid phosphatase (PAP) isoenzymes, designated PAP-A and PAP-B, were isolated from human seminal plasma by sequential affinity chromatography on concanavalin A and L(+)-tartrate, a classic inhibitor of PAP. Both the major PAP-A and the minor PAP-B isoenzymes exhibited a similar molecular mass (100 and 105 kDa respectively), multiple pI values (5.05-5.35 and 5.05-5.12), and substrate and inhibitor specificity. Immunological characterization revealed that PAP-B possesses distinct antigenic determinants, in addition to the common sites shared with PAP-A. SDS/PAGE indicated that both isoenzymes are composed of two subunits of 50 kDa each. At high salt concentration, PAP-B dissociated completely into single subunits of 50 kDa, whereas PAP-A remained intact at 100 kDa. PAP-B was resolved by reverse-phase h.p.l.c. into three components, designated alpha, beta and gamma, each of 50 kDa, at a molar ratio of approx. 2:1:1. PAP-A contained a single component of molecular mass 50 kDa. The single component of PAP-A and the alpha component of PAP-B possessed identical amino acid compositions and N-terminal sequences, which were different from those of the beta and gamma components. These results indicate that human PAP contains three isoforms, alpha 2, alpha beta and alpha gamma. PAP-A, the major isoenzyme, is a homodimer consisting of two identical subunits (alpha 2), and PAP-B, the minor isoenzyme, is a mixture of two heterodimers, consisting of non-identical subunits (alpha beta and alpha gamma).
Skip Nav Destination
Research Article| August 01 1991
Homodimer and heterodimer subunits of human prostate acid phosphatase
H Lee ;
T M Chu ;
S S L Li ;
Biochem J (1991) 277 (3): 759–765.
- Views Icon Views
- Share Icon Share
H Lee, T M Chu, S S L Li, C L Lee; Homodimer and heterodimer subunits of human prostate acid phosphatase. Biochem J 1 August 1991; 277 (3): 759–765. doi: https://doi.org/10.1042/bj2770759
Download citation file:
Don't already have an account? Register
Get Access To This Article
Buy This Article