Physical Methods in the Study of Biopolymers. UV-MALDI Mass SWpectrometry in the characterization of (glyco)proteins of seminal plasma

A.S.CEREZO; R. ERRA-BALSELLS; H. NONAMI; J.M.SCACCIATI DE CEREZO

Anales de la Sociedad Científica Argentina

Lugar: Buenos Aires; Año: 2009

Abstract                   Seminal plasma is a complex fluid containing a mixture of (glyco)proteins   originated from the testis, epydimis and the accessory glands. The methodology mostly used to analyze  these mixtures has been the SDS-reducing D-  and  2D-PAGE, nevertheless this technique showed drawbacks inherent to the methodology and/or to the complexity of the plasma itself. The usefulness of the UV-MALDI mass spectrometry for the study of (glyco)proteins is well known. Positive-ion mode UV-MALDI experiments  with isolated (glyco)proteins od seminal plasmas show the detection of a unique major peak (M+H)+ corresponding to each single compound together with, in some cases, small peaks of (M+2H)++  and  (2M+H)+. This corespondence major ion/compound together with its sensitivity and resolution make the UV-MALDI-TOF mass specrometry a useful technique for the (glyco)protein analysis of seminal fluids and for the direct identification of its components. The molecular masses of the major ions (M+H)+ of the seminal plasma proteins are in the range 12-14 kDa indicating a process of desaggregation of the (glyco)proteins  complexes previous to the volatilization/ionization step, which is consistent  with the high energy of the UV-laser used.                 The UV-MALDI technique can be used in two ways: trough the detrmination mof the molecualr masses which further identification suppose its previous knowledge or the use of standads  or the separation of the (glyco)protein by SDS-PAGE and further “in gel” digestion. The peptide mass fingerprint  of the digest obtained through UV-MALDI Ms submitted to an appropiate software allows the identification of the protein. Direct analysis of human seminal plasma revealed  the presence of over 30 peptides components in the mass range 5-10 kDa, but when most of these compounds were eliminated by dialysis the major (glyco)proteins appear in the range 12.5-14.0 kDa. This and previous studies of these mixtures permits hypothesize that the BSP-family (bovine seminal proteins-family) is larger than previously thought, and determine genetic polymorphism in samples of seminal plasma of different individuals.