HK1 Human

Hexokinase-1 is a ubiquitous form of hexokinase that localizes to the outer membrane of mitochondria . The enzyme is a homodimer with a regulatory N-terminal domain (residues 1-475) and a catalytic C-terminal domain (residues 476-917), connected by an alpha-helix . Both terminal domains are composed of a large subdomain and a small subdomain, with the flexible region of the C-terminal large subdomain (residues 766–810) proposed to interact with the base of ATP .

The HK1 gene spans approximately 131 kb and consists of 25 exons . Alternative splicing of its 5’ exons produces different transcripts in different cell types. For instance, exons 1-5 and exon 8 are testis-specific, while exon 6 is erythroid-specific . The ubiquitously expressed HK1 isoform starts from exon 7, which encodes the porin-binding domain (PBD) conserved in mammalian HK1 genes .

Mutations in the HK1 gene have been associated with hemolytic anemia due to hexokinase deficiency . This condition is characterized by the premature destruction of red blood cells, leading to various symptoms such as fatigue, jaundice, and an enlarged spleen.

Recombinant human Hexokinase-1 (rhHK-1) is produced using E. coli expression systems and is often tagged with a 6-His tag for purification purposes . The recombinant protein is typically supplied as a 0.2 μm filtered solution in Tris, NaCl, DTT, glucose, and glycerol . It is used in various research applications, including studies on glucose metabolism and enzyme kinetics.

The enzymatic activity of recombinant human HK1 is measured using a phosphatase-coupled method, with a specific activity of >700 pmol/min/μg . This high level of activity makes it a valuable tool for biochemical and physiological studies.

Recombinant human Hexokinase-1 should be stored at -20 to -70 °C to maintain its stability . It is important to avoid repeated freeze-thaw cycles to preserve the enzyme’s activity.