Md. Tabish Rehman, Safikur Rahman, Faizan Ahmad
Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India 110 025, India.

ABSTRACT

In vivo studies show that urea accumulates in large concentration in specific cells of various organisms. In vitro experiments show that cellular methylamine osmolytes (low molecular weight organic compounds) counteract the deleterious effects of urea on protein stability and function. Although urea and methylamines are found at 2:1 molar ratio in tissues, their opposing effects in vitro has been questioned on several grounds as the effect varies from absolute to nil compensation. Since salts at a very high molarity are co- accumulated with methylamines, we have therefore investigated the possible involvement of cellular salt, NaCl, in perfect urea-methylamine counteraction on protein stability and function. As a serendipitous discovery, we found that NaCl facilitate methylamine counteracting system from no or partial counteraction to perfect counteraction of urea’s effect of protein stability and function. These conclusions were drawn from the thermodynamic stability and functional activity measurements of RNase-A and lysozyme. Our results revealed that salts might be involved in protein interaction with charged osmolytes and hence in the urea-methylamine counteraction. Read more…