Calcium effect and pH-dependence on self-association and structural stability of the Apis mellifera major royal jelly protein 1

Abstract

The major royal jelly protein 1 (MRJP1) is the main glycoprotein in honey bee royal jelly. In brain tissues, MRJP1 is found in intercellular spaces and associated to cytoskeleton within cells. MRJP1 must be involved in multiple biological functions, yet there is a lack of structural information on the protein. MRJP1 was herein purified from royal jelly and characterized through electrophoresis and mass spectrometry as the same protein found in cerebral tissue. Unfolding curves obtained by circular dichroism analyses strongly suggest its high stability under different pHs. However, calcium ions made MRJP1 susceptible to temperature and pH effects. In the presence of 2 mM calcium, very high stabilities were achieved at pH 6.0 and 7.0 with δG 25 over 62 kJ mol -1. Overall, the present results represent a valuable effort aimed at the structural characterization of MRJP1, representing an essential step toward the determination of its roles in honey bee neural processes. © The Author(s) 2011.