Holocarboxylase synthetase catalyzes the covalent binding of biotin to histones in humans and other eukaryotes. Eleven biotinylation sites have been identified in histones H2A, H3, and H4. K12-biotinylated histone H4 is enriched in heterochromatin, repeat regions, and plays a role in gene repression. About 30% of the histone H4 molecules are biotinylated at K12 in histone H4 in human fibroblast...

We have evaluated senescence related changes in canine red blood cells (RBCs) using the biotinylation system, where RBCs are labeled in vivo with biotin at the beginning of their life span, and retrieved from circulation on immobilized avidin at the end of their life span. This approach avoids the controversial use of density gradient centrifugation to collect presumably old RBCs. Furthermore, ...

Low density lipoproteins were biotinylated via free amino groups using carbodiimide-activated biotin or D-biotin-N-hydroxysuccinimide ester. The receptor binding activity of the biotinylated LDL was determined by their ability to displace 125I-labeled LDL from the rat hepatic LDL receptor in the liposome filtration assay. LDL biotinylated with either of the two reagents was able to compete effe...

The HIV-1 TAT peptide has been used extensively for directing the intracellular delivery of an assortment of cargo, including DNA, liposomes and macromolecules. For protein delivery, a variety of TAT-fusion proteins have been described which link the TAT coding sequence to the protein coding sequence of interest. Streptavidin represents a potentially useful TAT-fusion protein because it could b...

A streptavidin-RNase H gene fusion was constructed by cloning the Thermus thermophilus RNase H coding sequence in the streptavidin expression vector pTSA18F. The gene was expressed in Escherichia coli, and the resulting fusion protein was purified to apparent homogeneity. The fusion protein was shown to have a molecular weight of 128 kDa and to consist of four subunits. Furthermore, heat treatm...