Avidin amino acid sequence

Huang TS, Delange RJ (1971) Egg white avidin. 2. Isolation, composition, and amino acid sequences of tryptic peptides. J Biol Chem 246(3) 686... 

Avidin is a basic glycoprotein (Table 11.5). Its amino acid sequence has been determined. Noteworthy is the finding that 15 positions (12% of the total sequence. Table 11.7) are identical with those of lysozyme. Avidin is a tetramer consisting of four identical subunits, each of which binds one mole of biotin. The dissociation constant of the avidin-biotin complex at pH 5.0 is k i/ki = 1.3 x 10 mol/1, i. e., it is extremely low. The free energy and free enthalpy of complex formation are AG = — 85kJ/mole and AH = —90kJ/mole, respectively. Avidin, in its form in egg white, is practically free of biotin, and presumably fulfills an antibacterial role. Of interest is the occurrence of a related biotin-binding protein (streptavidin) in Streptomyces spp., which has antibiotic properties. 

Table 11.7. Amino acid sequences of avidin (1) and lysozyme (2) ...

Fig. 1 Comparison of Streptavidin and avidin. a Conserved primary amino acid core sequences of streptavidin and avidin (Taken from [8]). b Overlay of peptide backbones of streptavidin and avidin monomers (Taken from [14])...

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