Studies on chemical modification of ovine luteinizing hormone and its subunits with different heterobifunctional cross-linking agents

Abstract

Increasing use of heterobifunctional cross-linking agents (HBCLA) in the design of defined conjugates for selective targeting and inducing immune response and to understand the significance of chemical modification of -NH₂group of lysine residues of native oLH and its α- and β- subunits of ovine luteinizing hormone (oLH) on, immunological, biological activity

of the hormone and α:β subunit recombination, the <img src='/image/spc_char/italics_e.gif' border=0>-NH₂ group(s) of oLH and its α- and β- subunits were separately and sequentially modified with different heterobifunctional cross-linking agents (HBCLA) such as N-succinimidyl 3-(2-pyridyldithio)propionate (SPDP), succinimidyl 6-[3-(2-pyridyldithio) propionamido] hexanoate (LC-SPDP), 2-iminothiolane (2IT), and 4-succinimidyloxcarbonyl-α-methyl-α(2-pyridyldithio)toluene (SMPT). The αoLH modified by HBCLA recombine to native βoLH was judged by reverse phase high performance chromatography (RP-HPLC) analysis. Similarly βoLH modified by HBCLA also recombine to native αoLH. The sequential modification of subunits led to progressive reduction in immunoreactivity, receptor binding and steroidogenic activity of the dimer. The modification of six or more <img src='/image/spc_char/italics_e.gif' border=0>-NH₂ groups in αoLH although recombine fully with native βoLH but failed to show receptor binding, anti-oLH antibody reactivity and steroidogenic activity. The modification upto four groups in αoLH compromised immunological and biological activities but further addition of two or more groups completely abolished immunological and biological activity of the recombinants indicating the importance of later two amino groups in the receptor binding and steroidogenic activity.</span></span></span></span></span></span></span></span></span></span></span>