The use of zwitterionic buffers in the separation of vaginal and seminal acid phosphatases in isoelectric focusing gels and the effect of neuraminidase treatment

Abstract

AbstractSeminal acid phosphatase (SAP) and vaginal acid phosphatase (VAP) bands, visualised by conventional isoelectric focusing have a wide pH range extending from approximately pH 4.0–6.0. Although a large proportion of these bands had similar isoelectric point (pI) values, the extremities of their respective ranges do not overlap. For SAP it was found that coincidental focusing tended not to occur withion a pH range of approxiamtely 4.3–5.2. The introduction of zwitterionic buffers to a conventional pH 4.0–6.0 Ampholine gradient produces a narrow pH gradient (4.3–5.2) in which semen‐specific SAP bands can be distinguished from VAP. This system has been used in an attempt to qualitatively identify SAP in the presence of VAP from a number of semen‐contaminated swabs. The interconvertibility of SAP into VAP has been demonstrated by neuraminidase treatment of SAP. When SAP was visualised on 15 cm gels containing pH 4–6 Ampholines it was observed that anodal bands faded and were converted into cathodal forms. Detailed examination of cathodal VAP and neuraminidase‐treated SAP was carried out on narrow pH gradients which enabled direct comparisons of individual isoenzymes. This provided confirmation that interconversion between the two forms was possible. Finally, a population survey of SAP patterns was carried out which failed to reveal any genetic polymorphism.