Four new and unusual proteins from bovine seminal plasma

| March 22, 2015 | 0 Comments


Published in: Biochemical Society Transactions, 1981, 9, 540-543.


Between 1956 and early 1970s, the following observations were made by my colleagues and myself in regard to macromolecular metabolism of spermatozoa (Bhargava, 1957; Bhargava et al., 1959; Abraham & Bhargava, 1963a,b; Iype et al., 1963; Premkumar & Bhargava, 1972, 1973; Bhargava & Reddy, 1976; P. M. Bhargava, P. T. Iype, J. Kusuma & E. Premkumar, unpublished work): (a) bovine spermatozoa synthesize protein and RNA; (b) the above syntheses are exclusively mitochondrial; (c) bovine seminal plasma inhibits RNA synthesis in spermatozoa immediately, and protein synthesis 15-30min later; (d) the inhibitor of RNA synthesis present in seminal plasma is macromolecular and susceptible to a proteinase. Several of these observations were subsequently confirmed by other workers (e.g. Mujica, 1976; Bragg & Handel, 1979).

In the mid-1960s we undertook the isolation of the above mentioned inhibitor of RNA synthesis. Since to do so, by using inhibition of RNA synthesis in spermatozoa as the assay system, seemed difficult on account of the time-consuming assay, we looked for another assay system. We argued that, as mitochondrial protein and RNA syntheses are susceptible to the same inhibitors as the corresponding syntheses in prokaryotes, the inhibitor might be expected to act as an antibacterial agent, and thus inhibit the growth of, say, Escherichia coli. Therefore, some 15 years ago, blissfully unaware of the fact that proteins do not easily get into E. coli, we set out to isolate an antimicrobial protein from bovine seminal fluid.

We have now isolated such a protein in what appears to be a pure form, and studied its properties and mechanism of action. We have named this protein ‘seminalplasmin’. Following up leads obtained during this work, we have also shown the presence, in bovine seminal plasma, of three other new proteins: ‘antiseminalplasmin’, which is an antagonist of seminalplasmin; ‘RNAase SPL’, a new ribonuclease with a hitherto undescribed set of specificities; and a new proteinase, ‘protease SPL’, with unusual properties. I describe below briefly the basic fractionation procedure for the isolation of these proteins, and some of their properties studied in my laboratory and that of Professor Karl-Heinz Scheit of Max-Planck-Institut fμr Biophysikalische Chemie, Göttingen, Germany, in collaboration with E. S. P. Reddy, Veena N. Rao, N. Sitaram, M. R. Das and M. Zimmer. I also acknowledge gratefully the collaboration of and help from Dr. E. Premkumar Reddy of National Institutes of Health, Bethesda, MD, U.S.A., Dr. Annamaria Torriani of Massachusetts Institute of Technology, Cambridge, MA, U.S.A., and Dr. Richard Ambler of University of Edinburgh, Edinburgh, Scotland, U.K.

PMID: 7030823


Four new and unusual proteins from bovine seminal plasma. P M BHARGAVA. Biochemical Society Transactions, 1981, 9, 540-543.


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