The protein HC chromophore is linked to the cysteine residue at position 34 of the polypeptide chain by a reduction-resistant bond and causes the charge heterogeneity of protein HC
Protein HC, an extremely charge-heterogeneous lipocalin, carries a yellow-brown fluorescent chromophore of unknown structure covalently bound at an unidentified site of its polypeptide chain. Two chromophore-carrying peptides with 60% of the chromophore material (defined as material absorbing light at 330 nm) were isolated from pepsin-digested native human protein HC by reversed-phase high perform