Partial purification and some properties of acetyl-coenzyme A carboxylase from bovine mammary tissue [proceedings].

and inactive fractions, with RF values of 0.15 and 0.34. Sliced gels eluted into NaHPOJ KH2P04 buffer, pH7.0, over 24h at 4°C showed the latter band to be inactive and the former to contain fumarase activity. Addition of the inactive protein to the active enzyme caused complete inhibition of activity. Dialysis of the initial pooled inactive protein over 36h resulted in high fumarase activity in the dialysis residue, and the dialysate after concentrated by ultrafdtration caused marked inhibition of both seminal-plasma and pig heart fumarase activity. The pH optimum of seminal-plasma fumarase was 7.0 with malate as substrate and 6.7 with fumarate as substrate. We have simultaneously purified four enzymes from a single pooled sample of human seminal plasma, and found that they have similar properties to enzymes purified from other human and animal sources. This is the k s t time that such a preparation has been achieved in this way, and may be of considerable use in investigating enzymes from small samples of biological material. In view of the possible importance of fumarase in spermatozoal-motility assay (Crabbe, 1976), a seminal-plasma fumarase inhibitor could be involved in a control of semen viability in vivo, particularly as we have found that part-two seminal-plasma ejaculates contain an inhibitor of fumarase activity in part-one ejaculated sperm cells and seminal plasma (J. Kavanagh & M. J. C. Crabbe, unpublished work). We gratefully acknowledge the help given by Dr. M. Read in collecting semen samples, Dr. W. G. Bardsley for helpful criticism, and Professor V. R. Tindall for provision of laboratory space. J. P. K. thanks the North West Regional Health Authority for financial support. Bardsley, W. G., Crabbe, M. J. C., Shindler, J. S. & Ashford, J. S . (1972) Biochem. J. 127,