Produced via a proprietary process resulting in a single biotin modification exclusively on the Nterminus of ubiquitin. This site-specific modification results in an ubiquitin that is fully functional at the C-terminus. This ubiquitin mutant lacks all reactive lysine residues which have been mutated to arginine. These mutations render the protein unable to form poly-ubiquitin chains and can be used as a negative control or to detect mono-ubiquitination. Detection with avidin-linked reagents allows for a higher efficiency and detection sensitivity than with antiubiquitin antibodies. Ideal as an alternative to radio-labeled ubiquitin.