{Reference Type}: Journal Article {Title}: Exploring an l-arabinose isomerase from cryophile bacteria Arthrobacter psychrolactophilus B7 for d-tagatose production. {Author}: Nirwantono R;Laksmi FA;Nuryana I;Firdausa S;Herawan D;Giyandini R;Hidayat AA; {Journal}: Int J Biol Macromol {Volume}: 254 {Issue}: 0 {Year}: 2024 Jan 2 {Factor}: 8.025 {DOI}: 10.1016/j.ijbiomac.2023.127781 {Abstract}: A novel l-arabinose isomerase (L-AI) from Arthrobacter psychrolactophilus (Ap L-AI) was successfully cloned and characterized. The enzyme catalyzes the isomerization of d-galactose into a rare sugar d-tagatose. The recombinant Ap L-AI had an approximate molecular weight of about 258 kDa, suggesting it was an aggregate of five 58 kDa monomers and became the first record as a homo-pentamer L-AI. The catalytic efficiency (kcat/Km) and Km for d-galactose were 0.32 mM-1 min-1 and 51.43 mM, respectively, while for l-arabinose, were 0.64 mM-1 min-1 and 23.41 mM, respectively. It had the highest activity at pH 7.0-7.5 and 60 °C in the presence of 0.250 mM Mn2+. Ap L-AI was discovered to be an outstanding thermostable enzyme that only lost its half-life value at 60 °C for >1000 min. These findings suggest that l-arabinose isomerase from Arthrobacter psychrolactophilus is a promising candidate for d-tagatose mass-production due to its industrially competitive temperature.