Bovine seminal ribonuclease

Oxidation of mono-cysteine peptides to the dimer is a straightforward reaction that can produce only the desired product. In the case of bis-cysteine peptides statistically the oxidation leads to the homodimers in parallel and antiparallel orientation as well as to the disulfide-bridged monomer and oligomers. When the two cysteine residues are placed in the adjacent position formation of homodimers is highly favored over the cyclic monomer (Section 6.1.5.1) and the product distribution depends strongly on the peptide concentration. Such a type of intermolecular disulfide bridging is present in bovine seminal ribonuclease, where an antiparallel alignment occurs at the interface of the dimer. 97 ... 

J. Sou k, P. PouCkovd, M. Zadinov, D. Hlouskov, D. Plocov, J. Strohalm, Z. Hrkal, T. Olej r and K. Ulbrich, Polymer conjugated bovine seminal ribonuclease inhibits growth of solid tumors and development of metastases in mice. Neoplasma, 48, 127-132 (2001). 

K. Ulbrich, J. Strohalm, D. Plocova, D. Oupicky, V. ubr, J. Soucek, P. Pouckovd and J. Matousek, Poly[N-(2-hydroxypropyl)-methacrylamide] conjugates of bovine seminal ribonuclease. Synthesis, physicochemical, and preliminary biological evaluation, J. Bioact. Compat. Polym., 15, 4-26 (2000). 

Figure 3 Bovine seminal ribonuclease, disulfide bridges shown in black. Structure drawn with HyperChem 5.0 from PDB entry 1BSR of Mazzarella L, Capasso S, Demasi D, Di Lorenzo G, Mattia CA and Zagari A (1993) Acta Crystallographica Section D49 389 The Protein Data Bank Bernstein FC ef a/(1977) Journal of Molecular Biology 2. 535-642.

Plate 47 The molecular structure of Bovine Seminal Ribonuclease, as determined using X-ray diffraction. The disulphide bridges are shown in yellow. The structure was drawn form the protein database entry drawn. See Proteinss Studied Using NMR Spectroscopy. Supplied by Dr G.G. Hoffmann. 

Pouckova P, Zadinova M, Hlouskova D, Strohalm J, Plocova D, Spunda M, Olejar T, Zitko M, Matousek J, Ulbrich K, Soucek J. Polymer-conjugated bovine pancreatic and seminal ribonucleases inhibit growth of human tumors in nude mice. J Cont Rel 2004 95 83-92. 

---